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M 2 3 1960

PB 151409

technical v2©te SO

MAGNETIC DRUM DIRECTORY AND

PROGRAMMING SYSTEM FOR

CODESORTING LETTER MAIL

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards; the determination of physical constants and

properties of materials; the development of methods and instruments for testing materials, devices,

and structures; advisory services to government agencies on scientific and technical problems; in- vention and development of devices to serve special needs of the Government; and the

1 development

of standard practices, codes, and specifications. The work includes basic and applied research,

development, engineering, instrumentation, testing, evaluation, calibration services, and various

consultation and information services. Research projects are also performed for other government

agencies when the work relates to and supplements the basic program of the Bureau or when the

Bureau's unique competence is required. The scope of activities is suggested by the listing of

divisions and sections on the inside of the back cover.

Publications

The results of the Bureau's work take the form of either actual equipment and devices or published papers. These papers appear either in the Bureau's own series of publications or in the journals

of professional and scientific societies. The Bureau itself publishes three periodicals available from

the Government Printing Office: The Journal of Research, published in four separate sections,

presents complete scientific and technical papers; the Technical News Bulletin presents summary

and preliminary reports on work in progress; and Basic Radio Propagation Predictions provides

data for determining the best frequencies to use for radio communications throughout the world.

There are also five series of nonperiodical publications: Monographs, Applied Mathematics Series,

Handbooks, Miscellaneous Publications, and Technical Notes. Information on the Bureau's publications can be found in NBS Circular 460, Publications of the

National Bureau of Standards ($1.25) and its Supplement ($1.50), available from the Superintendent

of Documents, Government Printing Office, Washington 25, D.C.
NATIONAL BUREAU OF STANDARDS

technical <ylote

50

JUNE 1960

MAGNETIC DRUM DIRECTORY AND PROGRAMMING SYSTEM

FOR CODESORTING LETTER MAIL

Peter C. Tosini

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature. They are for sale by the Office of Technical Services, U. S. Department of Commerce, Washington 25, D. C.

DISTRIBUTED BY

UNITED STATES DEPARTMENT OF COMMERCE

OFFICE OF TECHNICAL SERVICES

WASHINGTON 25, D. C.

Price $1.75
TABLE OF CONTENTS

Page

1. INTRODUCTION

1. Objectives and Scope 1

2. CODED ADDRESS FIELDS

2. Introduction 2

2. 1 Evaluative Criteria 2

2. 2 Analysis of Field Usage 3

2.2. 1 Uniqueness of Local Fields 3

2. 2. 2 Uniqueness of Outgoing Fields 4

2.2.3 Field Flexibility and Ease of

Coding Effort 4

2.3 Description of Plan E-l 5

2. 3. 1 Local Mail - Standard Case 5

2. 3. 2 Outgoing Mail 6

2.4 Summary 7

3. LOCAL AND OUTGOING TRANSLATION PROGRAMS

3. Introduction 14

3. 1 Memory Information

Storage - Local Directory 14

3. 2 Serial Programming - Local Mail Sort 16

3. 3 Serial Programming - Outgoing Mail Sort 22

3. 4 Summary 24

4. EXTENSION OF SERIAL PROGRAMMING

4. Introduction 24

4. 1 Short Coding 24

4. 2 Minimum Redundancy Coding 27

4. 3 Non-Standard .Addresses 28

-li-
TABLE OF CONTENTS (CONT'D)

Page

4. 3. 1 Section Designation 28

4. 3. 2 Intersections 30

4. 3. 3 Box Mail 30

4. 3. 4 Named Destinations 30

4.4 Special Situations 31

4.4. 1 Room Numbers 31

4.4.2 Odd-Even Carriers 31

4. 5 Summary 32

5. BINARY CODING AND DIRECTORY PREPARATION

5. Introduction 32

5. 1 Characters Required 32

5. 2 Unique Bit Combinations Required 34

5. 3 Bits per Character 35

5.4 Data Processing Equipment Considerations 35

5. 4. 1 Coding Vocabulary 36

5. 4. 2 Memory Vocabulary 37

5. 5 Suggested Coding Keyboard 40

5. 6 Directory Preparation 41

5. 7 Summary 42

6. DISCUSSION OF SYSTEM

6. Introduction 44

6. 1 Programming 44

6. 2 Memory 46

6. 2. 1 Serial Predirectory and

Directory 46

6.2.2 Serial Directories,

Predirectory Channel Selection 47

6. 2. 3 Serial Directory,

Integral Predirectory 48

6. 2. 4 Parallel Storage,

Integral Predirectory 48

-iii-
TABLE OF CONTENTS (CONT'D)

Pag<

6. 3 Input-Output Considerations 49

6. 4 Summary 50

I /

-iv-
LIST OF TABLES

Page

Table

I. Reduction Rules 8

II. State Name Abbreviations 9

III. Street Type Abbreviations 11

IV. Abbreviations for Commonly Used Beginnings

and Endings 12

V. Frequency Alphabet 13

VI. Washington, D. C. Local Field Entries

(PlanE-1) 33

VII. Parallel Storage Entries 51

-v-
LIST OF FIGURES

Figure Page

1. Local Mail Sort Program 25

2. Outgoing Mail Sort Program 26

3. Coding Keyboard 43

4. Serial Predirectory and Directory 52

5. Serial Directories, Predirectory Channel Selection 52

6. Sector Specification . 53

7. Serial Directory, Integral Predirectory .... 54

8. Parallel Storage, Integral Predirectory .... 54

-VI-
ACKNOWLEDGEMENTS

The author wishes to express his appreciation to Mr. Arthur Holt

of the Rabinow Engineering Company whose report provided the basis

for this study. Further thanks are due to Professor Harry Goode of

the University of Michigan, Mr. Israel Rotkin of the Diamond

Ordnance Fuse Labs, and Mr. Martin Stark and Dr. Bernard Levin

of NBS, Section 12. 5, for their valuable suggestions and comments.

-vii-
ABSTRACT

This report is an analysis and extension of the Rabinow

Engineering Company's proposal for a magnetic drum file -directory

and special purpose computer to be used in a test coded-address

("codesorting") letter -mail sorting system scheduled for late I960

installation at the Washington, D. C. Post Office. The report is

composed of 6 major sections that successively examine the major

considerations involved. A short introduction is presented first.

Then the general problem of coding the fields composing addresses

is discussed. This area is analyzed in terms of facilitating both the

human coding process and the computer coded address-to-binnumber translation. Addresses are classified into two types:

"standard" and "non-standard". When coded, their fields must be

unique and yet be sufficiently flexible to specify a variety of addresses,

They must furthermore adequately specify some more common forms

of misaddressed mail that is presently correctly sorted manually. A

slightly amended form of Coding Plan E-l is then presented and

analyzed in terms of the conditions specified for coded addresses in

general.

After the presentation of the coding area, the local mail sort

translation program of the Rabinow proposal is discussed in detail.

It is then extended to include the outgoing mail translation program

and non-standard and special address forms. The information and

instruction characters necessitated by the programs are listed in

detail and the effects of the file -directory source document preparation determined. A coding keyboard is then suggested.

The programming is then reexamined and it is determined that

all addresses can be treated as special cases of the standard address

forms at an increased cost in memory space and with a saving in the

special instruction symbols required. Finally, alternative methods

of file -directory information storage are explored and evaluated in

terms of memory space requirements, table look-up and directory

access times, and conceptual simplicity.

-viii-
MAGNETIC DRUM DIRECTORY AND PROGRAMMING SYSTEM

FOR CODESORTING LETTER MAIL

Peter C. Tosinl

1. INTRODUCTION

1. Objectives and Scope

The purposes of this report are: (1) to examine the major

concepts involved in designing a magnetic drum directory and

programming system for coded-address sorting ("codesorting")

letter mail in general; and (2) to develop these through modifications

and extensions to accommodate local and outgoing sorting for the

Washington, D. C. Post Office in particular. It is restricted to one

distributor separating local mail to carriers and "directs"

(destinations receiving large volumes of mail), and outgoing mail to

cities and "state residues" (alphabetic ranges of cities within a state).

The specialized problems encountered in multi -machine and multipass sorting, sorting to carrier walk, and sorting to time -varying

destinations are not discussed.

Codesorting can be described as a series of five distinct

operations:

(1) Address coding (Plan E-l,— the best presently available

set of rules for abbreviating literal address items by a

selective choice of letters, is assumed in this study),

(2) Imprinting coded address on envelope,

(3) Coded address reading and memory matching,

(4) Codewheel setting,

(5) Transporting letter to its associated bin.

Operations(2) and (3) are primarily concerned with coding,

memory storage, and programming, and their analysis forms the

basis of the report. The report first presents an expository

discussion of the interrelated factors affecting memory storage and

programming. It then relates these to the sequential steps

comprising the memory matching program.

Essentially, the report is a detailed analysis and extension of the

Rabinow serial programming proposal. Jy The analysis and

extensions are developed through the following criteria:

—' M. C. Stark, unpublished report.

2/ A. Holt, Rabinow Engineering Co. , unpublished report partially

presented in A. Holt, "An Electronic Directory for Sorting Mail, " Proceedings of the Eastern Joint Computer Conference, Dec. 3-5,

1958, pp 1<FW.
(1) Operational feasibility,

(2) Operational flexibility, and

(3) Reduction of coding operator effort.

2. CODED ADDRESS FIELDS

2. Introduction

The information specifying any address is generally composed

of a set of variable -length fields. Local mail is usually described

by building number, street name, street type, and, if necessary,

section; while outgoing mail is designated by city and state. However,

variations from these standard forms commonly occur. These are

discussed in a later section of the report.

The abbreviated and coded field information is imprinted on the

envelope and serves as the "source document" for the translation

program which yields a bin number as output. The format of the

imprinted fields was primarily designed to accommodate standard

address, forms. Four such fields are available for specifying local

mail: zJ

(1) Building Number Field,

(2) Street Name Field,

(3) Street Type Field, and

(4) Section Designation Field.

Two fields describe outgoing mail:

( 1) City Field, and

(2) State Field.

2. 1 Evaluative Criteria

The fields provide the information for the establishment of a oneto-one correspondence between any coded address and its associated

entry within the memory. In the most general case, this functional

requirement imposes the following specifications:

V The final coding plan will make optimum use of "short codes"

(one -or -two -character identifications for specific destinations

receiving large volumes of mail). This will greatly diminish

the average coding time per letter.

-2-
(1) The fields must be uniquely interpretable. Each field

must be distinguishable from any other since each is

independently necessary for the complete specification

of an address. Several techniques are available for

achieving this individuality: (a) a flag can be introduced

before or after each field; (b) fields can be defined

according to position, e.g. , the n character of a coded local address would always signify the beginning

of the Street Name Field if all n-1 characters of the

Building Number Field were always filled; (c) exclusive

use of certain characters in certain fields, e.g., direction

symbols appearing only in the Section Designation Field;

and (d) a combination of the above.

(2) The fields must be flexible in usage. Since a variety of

address forms is used, the fields must be sufficiently

adaptable to specify uniquely each form. This requires

that the number of character positions per field and the

symbols representable within each character position

be adequate for specifying all the forms.

(3) The fields and the characters composing them must be

in forms suitable for input to, and interpretation by,

the logical circuitry which performs the memory

matching.

(4) Coding effort should be minimized. As a general criterion,

the average number of strokes per address should be

minimized. Each key-stroke should add to the information

content of a field until it is fully specified. Then, no more

strokes should be expended in filling unused portions of

fields.

2. 2 Analysis of Field Usage

2. 2. 1 Uniqueness of Local Fields:

(1) An individual address may or may not require a section designation. No confusion arises from this

if the characters for section designations are used

in no other fields.

(2) The Street Type Field is used on every local address

and its characters may be identical to any of those in

the Street Name Field. But, the field remains

uniquely identifiable if the address is referenced from

right -to -left. Then, the first character that is not a section designation character is a street type

character.

(3) Confusion can arise between the Building Number

and Street Name fields since the same characters

-3-
can be used in both. This difficulty can be resolved

however, by having the coder introduce a special

symbol at tne end of the Building Number Field.

An alternative, if the field lengths were fixed,

would be to have the operator always fill completely

either the Building Number or Street Name fields.

This would require the entry of zeros in the unused

portion of the field (an operation that might be

performed much like tabulating on a typewriter). The

fields could thereby be uniquely specified by reading

the address from left to right if the Building Number

Field were completely filled, and by reading from

right to left if the Street Name Field were filled.

The use of the special symbol denoting the end of

the Building Number Field seems to be the more

acceptable since it should simplify coding equipment

without increasing coding time. Any character that is

not used in either of the two fields would be acceptable

as the special symbol.

2.2:. 2 Uniqueness of Outgoing Fields:

The City-State Field is generally composed of six

consecutive characters. The last two always designate

the state, and the first four the city. Therefore the fields

are uniquely defined by their relative positions. One -or - two character short codes for certain cities will also be

used. They will not require a state abbreviation and will

not use the entire six character outgoing field. These will

also be unique since any such address is known, by

definition, to be a short-coded city. Confusion can occur,

though, between local and outgoing destinations having

identical short codes, if both are sorted simultaneously.

In this case, a special identification symbol can be

automatically added to the outgoing short code when the

coding station letter -forwarding mechanism is actuated by

the outgoing release key.

2. 2. 3 Field Flexibility and Ease of Coding Effort:

The local fields are quite flexible since they may be

composed of a variable number of both alphabetic and

numeric characters. No flexibility is required of the

outgoing fields since they specify only the standard outgoing

address form or short-coded cities. A detailed discussion

of the requirements for local-field flexibility is presented

in a later section of the report.

The analysis of field usage suggests that considerable

simplification may result if the translation program can treat the

Street Name, Type, and Section Designation Fields as a single field.

As will be seen, this is indeed the case. Local standard addresses

-4-
e

are then specified by only two fields instead of four. These are

separated by an End -of -Building -Number -Field symbol which

simplifies their reading and transfer to registers. The suggested

use of local and outgoing fields is presented in the following

detailed description of Plan E-l.

2. 3 Description of Plan E-l

Plan E-l is a set of rules for reducing the length of addresses

while retaining their information content. These rules determine

the transcription, reduction, and abbreviation of address items into

the following coding fields:

Local Mail

(1) Building Number Field* (up to 5 characters)

(2) Street Name Field (up to 4 characters)

(3) Street Type Field (1 character)

(4) Section Designation Field (1 character)

Outgoing Mail

(1) City Field (up to 4 characters)

(2) State Field (2 characters)

2. 3. 1 Local Mail -- Standard Case:

Local mail is generally specified by a building

number, street name, street type, and section designation.

These items are entered into their corresponding fields

according to the following rules:

(1) Numeric items are transcribed directly.

(2) Alphabetic items are reduced according to the

rules of Table! (P 8 ), with the exception of

spelled-out numbers, which are treated as

numerics.

(3) State names used as street names, are^coded

with the abbreviations of Table II (P 9 ).

The Building Number Field is always followed by a one -character

End -of -Building -Number -Field symbol which serves as a reference point ior address reading and differentiation between

outgoing and local addresses.

-5-
(4) Fractions and letters following building numbers

are ignored but letters preceding them are

accepted. The letter x is used to designate

the fraction \/z in half -streets; e.g.,

6 1/2 Street, N. W.

(5) Street types are designated by the abbreviations

of Table III (PI 1).

(6) Section designations are specified by the

following four one -character symbols:

North or Northeast (Ne)

East or Southeast (s£)

South or Southwest (Sw)

West or Northwest (nW)

These symbols are distinct from the directional

beginnings of Table IV.

Some examples of local coding are:

2502 Franklin Avenue 2502*frnia

10 Main Street 10*mains

146 Fifth Avenue 146#5a

1600 Commonwealth Avenue, N. E. 1600#cmnha(Ne)

257 44th Place, North 257*44p(Ne)

2.3.2 Outgoing Mail

Outgoing addresses are specified by city and state.

These are entered into their corresponding coding fields

according to the following rules:

(1) City names of four letters or less are transcribed

directly.

(2) City names of more than four letters are reduced

to four letters by the reduction rules of Table 1.

(3) City names consisting of more than one word are

treated as a single word.

(4) Commonly used beginnings and endings of city

names are abbreviated by the set of abbreviations

in Table IV (P 12). (These are the only uppercase letters used in the coding process.

)

(5) Numeric numbers are spelled out and treated as

alphabetic s.

-6-
(6) State names are abbreviated with the set of

abbreviations in Table II. Some examples of outgoing coding follow. As is

seen, the state abbreviation immediately follows the

city name.

Laustin, Tex. lusiex

Stone, Ind. stnein

Allen, Ga. alengg

West Middlesex, Conn. Zmdxct

Mount Carmel, N. Y. Mcrlzq

Lexington, Ky. lxnNky

2. 4 Summary

The use of local and outgoing fields for specifying standardly

addressed letters has been presented. Specification of non-standard

address forms is discussed in a later section of the report.

-7-
TABLE I

Reduction Rules

Step Operation

1 A Take the first abbreviation.

B Take the first letter.

2 A Take the second of two successive vowels.

B Take the second of a double consonant.

C Take the next consonant.

3 A If only two letters remain, take them.

B Take the second of two successive vowels.

C Take tiher. next consonant.

4 A Take the ending abbreviation.

B If only one letter remains, take it. C Take the less frequent of the last two letters

(See Table V (P 13) for frequency alphabet.)

Note: Proceed through the steps, starting with Operation A of

Step 1. If operation A applies, do it and go on to next

step. If it does not apply, continue through the operations

of the step until one does apply. Continue through steps

2, 3, and 4 in this manner until reduction is completed.

Items of four or fewer characters are transcribed directly.

Source: Psychological Research Associates, Inc.,

unp ublished report.

-8-
TABLE II State Name Abb reviations

State Name Abbreviation

Alabama al

Alaska aa

Arizona az

Arkansas ak

California yf

Canal Zone cz

Colorado CO

Connecticut ct

Delaware de

District of Columbia dc

Florida fl Georgia

gg

Hawaii hw

Idaho id

Illinois bp

Indiana in

Iowa iw

Kansas ks

Kentucky- ky

Louisiana lu

Maine me

Maryland md

Massachusetts ma

Michigan mh

Minnesota mn

Mississippi ms

Missouri mo

Montana mt

Nebraska nb

Nevada nv

-9-
Table II (Continued)

State Name Abbreviation

New Hampshire nh

New Jersey js

New Mexico hv

New York zq

North Carolina nc

North Dakota nd

Ohio oh

Oklahoma ok

Oregon or

Pennsylvania xm

Puerto Rico pr

Rhode Island ri

South Carolina sc South Dakota sd

Tennessee tn

Texas ex

Utah ut

Vermont vt

Virginia vg

Washington wg

West Virginia wv

Wisconsin wi

Wyoming wy

Source: M. C. Stark and I. Rotkin, unpublished report.

-10-
Source:

TABLE III Street Type Abbreviations —

Street Type Abbreviation

street s avenue a road r place P

drive d

court c lane 1 terrace t boulevard y

circle y

crescent y

heights y

highway y

manor y

park y

square y

parkway y

row y

trail y

turnpike y

walk y

way y

alley y

M. C. Stark and I. Rotkin, unpublished report.

— These are the only street types explicitly coded. Other

str'eet types (quite rare) are incorporated with the street

name and coded as an integral part of it. Then the letter s is entered as the resulting item's street type.

-11-
TABLE IV

Abbreviations for Commonly Used

Beginnings and Endings

^Beginning Abbreviation Beginning Abb:reviation

North or Northeast I San, Santa,

Saint

S

East or Southeast Mont, Mount,

Mountain

M

South or Southwest X Port P

West or Northwest z Glen G

New N Lake K

Ending* Abbreviation Ending* Abbreviation

ville V lake K

valley- Y land L

ton N son S

town T spring G

burg B fall A

dale D field F

creek R park P

center C wood W

city T

Source: M. C. Stark, unpublished report.

Including the plurals of these.

-12-
TABLE V

Frequency Alphabet

(In descending order of frequency)

e

r n

a

t

1

o d

y

c

i k

h

m

g

f w

u

P

X

b

v

z

j

q

Source: Psychological Research Associates, Inc.,

unpublished report.

-13-
3. LOCAL AND OUTGOING TRANSLATION PROGRAMS

3. Introduction

It would appear that the general problem of translating coded

destinations into their associated bin numbers can be accomplished

in two ways:

(1) Coded destinations can be arithmetically manipulated

to generate bin numbers (within acceptable limits of

duplication).

(2) Coded destinations can be matched against a memory

directory which includes all the coded destinations and

their associated bin numbers.

Method (1) is the more direct of the two. But its use is precluded

by a specific operational requirement of codesorting mail. Many

different destinations must be sorted to the same bins e.g., all

destinations comprising a carrier's route must be sorted to that

carrier's bin. The translation procedure must therefore yield bin

numbers which are arithmetically independent of the coded

destination. Therefore, method (1) is not applicable (though it is

useful in generating a beginning reading address for a random-access

memory system using method (2)).

Method (2) does provide complete flexibility of bin number output

and therefore satisfies the criterion. It is the basis of the Rabinow

programming proposal. The imprinted address fields are read and

sent to registers where comparisons are made with entries read in

from the memory drum. When an equality match occurs, the

appropriate bin number is read out and sent to the codewheel setter.

The program is composed of instructions appearing before each

memory item. These initiate and guide the arithmetic, comparative,

and transfer operations the program comprises.

3. 1 Memory Information Storage - Local Directory

The storage pattern of information corresponds to the sequence

of operations necessary for bin determination. For local standardly

addressed mail, a series of tests on different levels of inclusiveness

is performed where each test successively narrows the search area

for the corresponding memory entries. For instance, a standardly

addressed local letter is described by street name, type, section,

and building number. Each of these fields must be matched for bin

determination. The memory reflects this by the organization of its

-14-
information. Each street is entered once, followed by its type and

section. _V Following these are listed entries which specify building

numbers on the street. Here, use is made of the fact that carriers

deliver mail to continuous groups of buildings. These groups are

termed "breaks "and their lower and upper bounds are, respectively,

the first and last buildings of the continuous set of carrier stops.

Entered after the upper limit of each break is the bin number of the

carrier serving that break. Consequently, the totality of breaks and

carrier entries for any street completely specifies the carriers

delivering letters to any building on that street. The break

organization consequently obviates the need for individually specifying

each building on every street.

Memory entries are stored on the channels of a magnetic drum.

A variety of information storage patterns is therefore possible.

These vary from full -parallel to full-serial. The full-parallel

method stores coded fields of information in fixed-length sets of

channels on a line along successive channels. Each set of channels

specifies a different field, i.e. , the first set, the street; the second,

the type; the third, the section; the fourth, the break; and the fifth,

the carrier. Successive vertical sets of these horizontal sets are

required to describe the totality of breaks and carriers on any

individual street. This results in a duplication of the information

fixed for any street and is wasteful of memory space. Furthermore,

since the number of channels per field is fixed and the information

entered in each one varies in length, some of the sets will not be

completely filled and will again waste memory space. The parallel

mode also requires that all channels specifying an address be read

simultaneously. This necessitates an amplifier for each channel

being read.

The full serial method stores the coded information sequentially

along a channel rather than linearly across the channels. It does

not require fixed sets of memory space to the extent that the parallel

mode does and thus permits more compression of the information

with a resulting saving in memory space. And since only one channel

is read at any time, only one amplifier is required. The serial

method does require special flag symbols, though, to identify the

stored items since the items' types are not determined by their

location on the drum as was the case with the parallel method of

storage. Information is entered as follows: The coded street name,

type, and section are successively entered, followed by the upper

limit of the first break on the street and the carrier serving it. Then

yThis is directly analogous to the present scheme of distribution

for manual sorting. An alternative organization would be

according to building numbers instead of street names. That is,

each hundred's block would appear once and be followed by all

the street names having that specific block of building numbers.

This method would not have the flexibility of the street name

organization and would require more memory space.

-15-
the upper bounds of all the successive breaks followed by their bin

numbers are entered. Preceding each of these entries is its flag

symbol identifying the type of entry. These flag symbols also initiate

the computer operations which perform the matching program.

Full-serial storage appears to be the more acceptable of the two

because of its efficient memory space utilization and the flexibility

afforded by extensions of its special order concept. But these

apparent advantages necessitate increased complexity of the

electronic circuitry for interpreting and acting upon the special

symbols. The two storage methods require different programs for

memory matching. Serial programming will now be presented.

Parallel programming and a more detailed analysis of storage

alternatives are discussed in Section 6.2.

3. 2 Serial Programming - Local Mail Sort

The memory matching program is essentially a set of

comparisons between the fields imprinted on the envelopes and

stored in registers, and the information read from the drum

directory and stored in temporary registers. A flow chart for

standardly addressed local mail is presented in Figure 1 (P25 ). The

successive steps are explained below. The chart is phrased in terms

of the logical comparisons that must be made for memory matching.

It is not implied that the operations fully represent the actual physical

equipment requirements or information flow.

Step 1The process begins when the coded fields on the envelope are

sensed by reading heads, amplified, and transferred to registers.

There are two registers: the Street Register (SR); and the Building

Number Register (BR). The Street Register stores the Street Name,

Type and Section fields as an integral unit, while the Building Number

Register stores the Building Number Field.

This might be done by reading the coded envelope from right to

left and transferring the characters into the Street Register until the

end -of -building number symbol is sensed. Then, continuing reading

from right to left, the building number is transferred into its

register. The reading consequently proceeds from the least to the

most significant characters of the fields. By transferring the

characters to the registers as they are read (from right to left) the

information in the registers will have its least significant character

in the right -most register position. An alternative method might be

to read the envelope fields simultaneously; the Building Number Field

from left to right and the Street Fields from right to left until the endof -building symbol is reached. The street fields could be transferred

from right to left as before, but the building number would usually

require shifting to the right for the least significant position criterion

to be satisfied. This method seems faster but may be more expensive.

-16-
After the fields are sent to registers, channel selection is

performed. This operation determines which of the drum's channels

stores the information concerning the particular street in the street

register. Here the concept of arithmetic interpretation of binarycoded characters is used. By using a "collating sequence" binarycoded-decimal code (one in which the addition of unity to an alphanumeric yields the succeeding alpha -numeric) the memory entries

can be organized alphabetically. Consequently, all numeric streets

and their breaks and carriers will be entered in numerical order

followed by the alphabetically ordered alphabetic streets and their

breaks and carriers. Therefore, the range of entries on any channel

is specified by the magnitude of the first and last streets listed in the

channel. This is the basis for the channel selection procedure

proposed by Rabinow. ±j The Rabinow method utilizes a separate predirectory which is a consecutive listing of the last street entered in

each channel, with each street followed by its channel number. These

are compared against the street stored in the street register until one

is found to be greater than or equal to that street. Since the streets

are numerically ordered-, this test specifies the desired channel. The

channel number is then read and initiates the reading of the channel.

If a street extends into another channel, the Building Number Field

can be tested simultaneously with the street field. By "street" in the

preceding and following discussions is meant the street name, type,

and section. An alternative proposal performs channel selection by

a similar series of tests between the stored street and the end -of - channel streets. The test path is in the form of a "tree" where each

test (branch) successively halves the possible search area; i.e. , the

first test tells which half of the drum the street is in; the second,

which quarter; the third, which eighth; etc. Therefore, n tests

suffice for channel determination on anv 2n channel drum. e. a. . six tests for a 64 channel drum. Again, this may be extended to

include the case of a street extending into more than one channel by

including a simultaneous test on the Building Number Field.

Step 2

The memory layout and programming are designed with the street

entry as the key item. That is, street determination fixes the range

where the carrier number is found on the channel. Since serial

storage is used, a special symbol (sj) is entered before each street.

The next step after channel selection is than to find the s^ symbol

that passes the drum reading head. But, several problems arise in

meaningfully interpreting the stored information since it is in binary

form. The reading head can interpret only pulses and, therefore,

without outside control cannot determine the number of "no pulses" it is "reading". This problem can apparently be resolved in at least

three ways:

-' A. Holt, Op. cit.

-17-
(1) The binary code for any character can be chosen so that

a binary one is never followed by more than one binary

zero and any character always begins with a binary one. This severely restricts the characters representable by

any fixed number of bits.

(2) Binary ones could still be represented by positive pulses,

but binary zeros by negative pulses instead of the absence

of pulses.

(3) A drum channel can be reserved for reference pulses.

That is, the channel is completely filled with binary ones.

When a channel is read, it is continuously compared with

this channel. When both have simultaneous pulses, a

binary one is being read. When only the reference channel

has a pulse, then a binary zero is being read.

(4) Since the drum speed is uniform to a high degree, a device

rigidly coupled to the drum can generate reference pulses

at the same rate as (3).

An allied problem is that without further control the reading

head cannot distinguish whether it is reading the beginning, ending or

middle of the s\ symbol. This control can be provided in several

alternative ways:

(a) A continuous comparison can be made between the stream

of bits read from the channel and a stored s \ symbol. An

exact match signifies that the symbol has been reached

and reading of the street name can begin immediately.

This method is possible as long as any serial combination

of the other character bit representations cannot produce

the code for the symbol.

(b) A number of zeros greater than the greatest number of

consecutive zeros in any character's code can be entered

before the symbol. These can indicate that if follows

and might even replace it.

(c) If all readings are begun at a fixed angular position of the

drum, one timing pulse can determine the starting point

for reading on all channels. This requires an average of

one -half a drum revolution before reading can be initiated.

(d) An "address channel", marked with pulses at regular

intervals could also be used. The s^ symbols on all the

other channels would be aligned with these pulses. This,

as the first two alternatives, would permit low access

time because of rapid entry, but would be wasteful of

memory space because of the restrictions it imposes on

the format of the entered items.

-18-
The interpretation problem is greatly simplified if all characters

are specified by the same number of bits. It will be discussed

further after completion of this discussion of serial programming.

After the si symbol is sensed and interpreted, all the bits

specifying the street are sent to the Temporary Street Register (TSR),

But the imprinted coded streets will generally vary in length, i. e. , some streets, with their type and section, can be specified by three

characters while others require up to six characters. Furthermore,

they appear in the SR with their least significant character in the

right -most register position. The characters transferred to the

TSR must therefore be aligned with those in the SR if the subsequent

equality test is to be made. Some alternative methods of controlling

the transfer of bits are:

(1) Streets can be entered in the memory so they take the

maximum number of characters by inserting zeros in

the unused character positions. Consequently, every

street is specified by six characters and a constant

number of bits is always transferred to the TSR after the

si symbol is interpreted. But this procedure is quite

wasteful of memory space.

(2) Different si symbols can be used depending upon the

number of characters in the street item following them.

This would necessitate six orders instead of only one. But the recognition circuitry could possibly be simplified

if the orders were composed of two parts: (a) a "prefix"

order (the usual si symbol); and (b) a "suffix" group of

bits specifying the number of characters to be sent to the

register.

(3) The street entry is immediately followed by either of

two instruction symbols (s2 or S3). Therefore, bits can

be sent to the register until either of these is sensed.

If method (1) is used, transfer can proceed directly from

left to right and completely fill the TSR, with the right-most character

automatically located in the right -most position of the register. But

the other methods will generally require some intermediate storage

and counting devices for the shifting operation required to properly

align the less-than-six character streets in the registers. 2/

2/— The alignment problem is easily resolved if the imprinted

address fields are read from left -to -right and their corresponding registers are filled from left -to -right. Then the

register fields are in direct alignment with the temporary

register fields.

-19-
Method (3) also requires all alpha -numeric characters to be

composed of the same number of bits. This condition does not

appear strictly necessary for the first two methods. But to eliminate

possible redundancy that could occur when serial combinations of

character bit configurations are interpretable as a third character,

the characters should each have the same number of bits in any of

the methods.

Steps 3 and 4

The street item from the envelope, stored in the Street Register,

is then compared for equality with the memory street stored in the

Temporary Street Register. If equality occurs, it means that the

correct street has been found and the program continues to Step 5.

If equality does not occur, the program returns to Step 4 and

continues searching for the appropriate street. If because of some

error the desired street is not located in the particular channel

being searched, the search will continue indefinitely in a loop.

Consequently, some method must be provided to send error letters

to an error bin when the drum has made more than one revolution

after the beginning of reading.

Step 5

After the correct street is found, the building number must be

matched with its associated entry within that street. Since sorting

is done to the carrier, and since carriers deliver to continuous sets

of buildings ("breaks"), it is necessary to specify only the break

limits instead of all individual building numbers. However, certain

buildings ("exceptions") are physically located within carriers'

breaks but are not served by those carriers. This mail must

therefore be sorted to its own bins. Exceptions are entered

immediately preceding the break which numerically contains them.

As was done with streets, exceptional building numbers and break

entries are preceded by special instruction symbols (s£ and S3

respectively) which identify them and control the programming.

The program, after fixing on the street, reads the next memory

character and tests to see if it is the S2 symb ol. If it is, then the

following item is known to be an exceptional building number and is

sent to the TBR. Then, the TBR is compared for equality with BR

which stores the building number read from the imprinted envelope.

If equality occurs, the program transfers to S tep 7. If not, control

is transferred back to Step 5. If the first or any other test against

the S£ symbol in Step 5 does not yield equality, control is transferred

to Step 6.

Step 6

If the test against the S£ symbol did not yield equality, the

character is tested against the break symbol (S3). If equality does

not occur, control is transferred back to Step 5. If it does, the entry

-20-
Step 7

Each break or exception is followed by a bin number symbol

(s^) and the bin number of the carrier serving it. After finding the

correct break or exception, the program reads the next character

and determines whether it is an S4I/, j*/. It them transfers the

fixed length bin number to the codewheel setter. Finally all registers

are cleared and the program is ready to process the next address.

3. 3 Serial Programming - Outgoing Mail Sort

The programming for outgoing mail is similar to that of local

mail. The imprinted information is read, sent to a register, and

successively compared with the sequential entries on the drum. But

it is much simpler since usually only one type of test is required

after channel selection. A tentative program is presented in Figure

2 (P. 26 ), and the successive steps are explained below:

Step 1The imprinted information consists of a four character City

Field followed immediately by a two character S tate Field. The six

characters are read and tested with key words that locate the correct

channel. The channel entries consist of sequentially entered cities,

each followed by its appropriate bin number. Each state's cities are

grouped alphabetically and each group is ordered according to the

alphabetical rank of the state. No two states'cities ever appear on a

single channel. Channel selection can therefore be performed by

placing the State Field before the City Field and testing on the resulting index word.

Step 2

After channel selection, the city field is transferred and stored

in the City Register (CR). Reading of the channel can begin, as will

be explained in Step 3, only at one position of the drum. When this

position is reached, the first four character City Field is sent to the

Temporary City Register (TCR).,

3/ If it is not, an error has occurred and the letter is directed to an

error bin after the drum has completed one revolution.

It should be noted that comparison tests must be delayed until the

registers are filled and not performed during the interval when

the registers are being filled. This can be accomplished by

inhibiting the output of the tests until the succeeding instruction

is interpreted. Tests are thereby performed character -bycharacter but not passed or failed until the complete items are

tested.

-22-
following the symbol is added to the TBR and stored there. This

entry is the upper limit of the first break on the street. Before the

addition, the TBR is empty, so the addition yields the upper limit of

the first break on the street. The BR is then compared against the

TBR. If it is less -than -or -equal -to the TBR, it means that the

building number is included in that first break, and the program shifts

to Step 7. If it is greater than the TBR, it means that the building

number is not included in the first break. The program therefore

shifts back to Step 5 and continues searching for the proper break or

exceptional building number. Exceptions and breaks are specified by

the arithmetic difference between the particular exception or break

and the exception or break item preceding it. This difference is

called the "Differential Building Number" (DBN) and for the case of

the first entry on a street equals the upper limit of the first break, or

the exceptional building number if one precedes the break.

Some memory space can be saved by incorporating a shift

technique with the instruction symbols. The great majority of

successive breaks differ by an even 100's number. Therefore, by

entering only the 100' s digit and shifting it before addition, the break

limit is specified without being fully entered. However, certain

successive break differentials do not follow this pattern and will have

to be fully stored and transferred. This will require the use of a

different S3 symbol which will not perform shifting. Differences

between successive exceptions, and exceptions and breaks, also

generally do not follow the pattern and will require full differential

storage and transfer. A similar proposed procedure is to store

only the characters differing between successive entries rather than

their arithmetic difference. This simplifies file -directory

preparation and is also amenable to the shifting technique.

Bit transfer problems, identical to those of Step 4, also occur in

Steps 5 and 6. Unless the special symbols specify the number of bits

to be transferred, the bits must be transferred in fixed-length blocks,

or else all characters and special symbols must be specified by the

same number of bits and transfer continued until a special symbol is

interpreted.

-21-
Step 3

The CR is then compared with the TCR for equality. If it occurs,

the correct entry has been found and the fixed-length bin number is

transferred to the codewheel setter and the registers are cleared. If

equality does not occur, the next city is read in and the test reperformed. Letters to any city having an entry in the drum can be

sorted to any chosen bin. However, many cities will not be entered

in the drum. These must be sorted to alphabetical residue

categories, as, for instance, a-1 and m-z. This can be done by

including alphabetically the residue "cities" lzzz and zzzz, and their

residue bin numbers, in the drum directory. Then, by performing a less-than-or-equal-to test on these entries, the residue mail is

grouped to its appropriate bin. This procedure requires that the

residue entries be preceded by a special symbol instructing the

computer to perform the less-than-or-equal-to test. Consequently,

every character read during drum reading must be compared against

the special symbol. The residue sorting concept further requires

that drum reading begin at the lowest alphabetical city on the channel,

thus precluding random entry into the drum and requiring an average

of one -half a drum revolution before reading can begin.

The additive technique used in the local mail programming is

extendable to outgoing mail. Any city can be entered as the numeric

difference between itself and the city immediately preceding it. These

differentials, when added to the cumulative total in the TCR, would

then produce the desired codes. This requires all the differentials to

either be four characters long, or to be preceded by special symbols

specifying the number of characters composing them. It could

conceivably require four characters for some differences so the

fixed -length differentials would be four characters long and

consequently would save no memory space. The variable -length

alternative method would require three special symbols and their

associated circuitry. Assuming the symbol would be one character,

only two characters of memory space could be saved in the extreme

case of a one character difference between successive city names.

For the case of a four character difference, five characters of

memory space would be required. A more reasonable proposed

solution appears to be the entry of only the characters differing

between successive cities.

The memory layout results in the repetition of many cities having

the same name but located in different states. An alternative storage

procedure might be to enter all cities alphabetically with no

duplication and no organization according to states. Then any city

name appearing in more than one state could be followed by the codes

for those states. City name (4 characters) duplication is thereby

eliminated at the expense of entering an equal number of previously

unnecessary state abbreviations (2 characters). This procedure

does not permit sorting to state residues and may require a special

symbol for the interpretation of the state abbreviations.

-23-
3. 4 Summary

Some characteristics of serial programming have been

presented. Its major complexities arise from the variable length

of address fields and the use of instruction symbols stored before

every entry on the drum. Possible extension of the serial programming concept to accommodate nonstandard local address forms is

discussed next.

4. EXTENSION OF SERIAL PROGRAMMING

4. Introduction

The proposed serial programs appear to be satisfactory for

sorting standard address forms. However, they may be refined

in the following areas:

(1) Short Coding

(2) Minimum redundancy coding

(3) Non-standard address coding, and

(4) Special situations.

These are discussed below and the suggested final use of E-l

summarized in Table VI (P33).

4. 1 Short Coding

Much local mail is destined for relatively few large receivers

of mail who will be specified by short codes. Under the present

system, the operator would have to:

(1) Type the short code,

(2) Type an end -of -building number symbol,

(3) Type a letter which would serve as a street, since the

street is the key item in the programming,

(4) Strike the Forward key.

This is clearly unsuitable since it greatly detracts from the

anticipated time savings accruing from short codes. The programming must therefore be modified to accept short codes without

special symbols. The operator should type only the code and strike

the Forward key. This might be done by testing the number of

characters on an envelope before Step 1 of the standard programming.

If there are three or less characters, then it is a short code and can

be immediately sent to the TSR and compared with the short codes

entered in the channel or channels reserved for them.

-24-
5<

a:o

cc

\-

cco

enoo

LU

a:o

Li.
2

a_i« i

DE

WHEE

LEAR

ALI

!EGISTER 2 O W- O O

III

oro UJ^

(- z £

or QO o <

UJ

GC

cro

hrt

>-HO

-*©

w > Q< o

UJ

cr

cr cdi ot z h- 2 CJ < UJ X -I O UJ > (/) h-CJ

cr

Ul

Iuj cr

cru

i-

</> o

UJ

cr>-u cr >- UJ

cr cd < 2 S<

croo

ito

enozo

I-o

CMUJ

crID

U.

2-

(_ CD ~ <Z -±

cr o z o I- o
The same problem occurs with outgoing mail since many cities

will be similarly designated. A test can also be performed in this

case on the number of characters.

4. 2 Minimum Redundancy Coding

The break, street name, type, and section organization of

Washington, D.C. , provides a unique representation for every building.

But it does this redundantly. That is, all fields are not required in

every case to uniquely specify individual buildings. This arises from

the exclusive nature of the break organization. All streets with the

same street name do not include the same numeric range of breaks.

Therefore, buildings on identically named streets in different sections

often are still uniquely identifiable even without the Street Type and

Direction fields! This characteristic implies a potential reduction

in coding time if decision rules can be formulated for extracting from

an address the minimum information required for its unique

specification. The memory entries would of course have to correspond

to these rules also.

Four interrelated rules seem to be applicable:

(1) Omit "street" as an entry in the Street Field for all

streets.

(2) Omit the Street Type Field entirely for named streets.

(3) Omit NW as a section designation in the Direction

Field for all streets.

(4) Omit Street Type and Direction fields for all named

streets.

Study of the Postal Zone Directory, Washington, D.C, 1959,

indicates that (1), (2), and (3), when applied, produce unique address

specifications; i.e. , letters are sorted to their proper carriers.

Rule (4) results in some missorting, i.e. , letters can occasionally

be sorted to the wrong carriers, but these carriers generally seem

to be in the correct zone. Consequently, only intra-station rather

than inter -station transfer of this mail is required. However, even

this level of redundancy is probably unacceptable.

The value apparently accruing from these rules may not be

sufficient to justify their use. Omitting the S ection Designation saves

one key stroke. But the letters must still be released by the striking

of a Forward key. If the Section Designation keys are linked to the

"Forward" key so as to automatically actuate it when they are

depressed, the one stroke saving is achieved without losing the section

information. Furthermore, the operator's decision to type or omit

the Street and/or Section Designation fields might take as long as the

key striking time. In addition, the address organization redundancy

was noted for the case of uncoded street names. Coded street names

-27-
are abbreviated and consequently have a lower information content. —

The previous redundancies may therefore be necessary for unique

address specification. Another factor is that even though the omission

rules may be practicable and economical they may have a high

"opportunity cost". That is, the time and energy expenced by the

operator in making these decisions as he codes might be more

profitably applied in other activities, e.g. , more careful examination

as to whether or not the address has a short code.

4. 3 Non-Standard Addresses

The public's addressing habits are such that mail is often

addressed in a non-standard format. Some of the more prevalent

variants will now be discus sed in relation to the serial program's

flexibility for accepting them.

4. 3. 1 Section Designation

A common departure from the standard form is the

omission of the section designation. This occurs more

frequently for NW streets than for those in other sections

and the present convention is to consider such streets to be

in the NW with the exception of several major arteries in

other sections. When confronted with an address whose

section is omitted, the programming should ideally perform

as follows:

(1) If the street and building number appear in only

one section it should be sorted to that section.

(2) If the street and building number appear in more

than one section, including the NW, it should be5 sorted to the NW section.

(3) If the street and building number appear in more

than one section (excluding the NW) the letter

should be sorted to an error bin.

The present serial programming is designed with the

section as an integral part of the street field. Consequently,

it can not now meet the above conditions. But modifications

for achieving them can be made in the coded information

fields and/or the memory entries and programming. A

possible method would be to omit the section designation

i/

Ideally, their relative information is the same. But, in general,

two different street names might yield the same coded street

name. Consequently, the street type and section fields would be

required for their unique specification.

-28-
from the coded addresses and the memory for all NW

streets and streets in other sections which: (1) are

commonly specified without a section designation; and

(2) do not have names and building numbers identical

to any streets in the NW. This seems feasible but

would require the coding operator to know and recognize

the streets, other than in the NW, which are to be so

treated. An objection is that some streets in the delivery

area appear outside the District and have no section

designations while having the same name as certain NW

streets. They would apparently be sorted to the NW. But,

fortunately, these streets' breaks and those of the NW

section are exclusive. Thus, mis sorting is prevented.

An alternative method would be to code the section

and retain its designation in the memory, but to extend

the special order concept. The Si symbol preceding the

NW street entries, would be modified to perform two

tests: The first in the standard manner; and if the first

did not yield equality, a second, performed on only the

street name and type fields stored in the TSR. Then, a

letter to a NW street would be sorted properly with or

without its section designation. This procedure requires

that the NW street entry be placed last in a group of

identical street name entries. It further requires that

if the second test was performed by shifting the TSR

contents one character, they must be re shifted without

losing the character after the test is performed. This

special order extension can be applied to selected streets

in other sections as long as these streets do not have

any house numbers that are the same as those on the

identically named NW streets. This method presumes

no operator scheme knowledge but would probably require

an excessive number of shifting operations and would unduly complicate the electronic circuitry.

A much more flexible solution would be to use a "Test Suppression Instruction" 2/ in the memory as follows :

(1) As the section designation for streets appearing

in only one s ection.

(2) As the street type in streets having only one

type.

The instruction character would have the property of

always passing an equality test with any other character.

2/— Similar to the "ignore" character of general-purpose computers,

-29-
The coding operator would then specify the NW section

for addresses with the section omitted, and "street" for

addresses with their street type omitted. This would fulfill the conditions specified at the beginning of this

discussion without requiring the coding operator to have

any scheme knowledge. Furthermore, it would correctly

sort letters with the "street" street type omitted.

In general then, the program can be modified so that

NW mail with no section designation will be properly

sorted and mail with no section designation, destined for

streets in other sections, can also be correctly sorted.

The restriction is that in any set of identically named

streets, mail lacking a section destination and destined

for building numbers common to that group of streets,

is sorted to only the NW street. This restriction is not

critical in view of the present convention of assuming

such mail to be NW. By using the Test -Suppression

character in the memory, the program can in addition

sort letters having their street types omitted. The

restriction in this case is that in any set of identically

named streets, mail lacking a street type arid destined

for building numbers common to that group of streets,

is sorted to only the "street" street.

4. 3. 2 Intersections

Buildings are often specified by an intersection of

two streets rather than a building number and street.

The program can handle this situation if the first street

is entered in the Building Number Field, the second in

the Street Name Field, and the Letter "i" in the Street

Type Field. The corresponding directory entries would

be entered as exceptions.

4. 3. 3 Box Mail

Lock box mail can be sorted by entering the box

number in the building number field and a "b" in the

street field. Corresponding memory entries would

consist of a b "street" and the upper limit of the box

numbers for successive stations with each followed by

a bin number for that station. This procedure is

analogous to the exception and break procedure used with

the standard address form.

4. 3. 4 Named Destinations

Some mail for many destinations such as firms,

embassies, hotels and apartments is addressed to the

name of the destination and does not specify the building

-30-
number. Some of this mail is for short -coded destinations

and consequently is easily sorted. But the remainder

presents a problem. Some of the names could be entered

in the memory, but many are difficult to reduce and code.

Furthermore, for efficient utilization of coding time, the

operator has to know whether the specific name being

coded is in the memory. A reasonable method of handling

these addresses would seem to be:

(1) Train operator to recognize and code names which

are entered in the memory and do not have short

codes. The recognition of names as non-shortcoded should require less memory effort than the

recall of short codes.

(2) Short-code the remainder to bins corresponding

to the type of destinations; e.g. , firms, schools,

apartments, etc.

4. 4 Special Situations

In addition to the above mentioned non-standard address forms,

the following situations commonly occur:

4. 4. 1 Room Numbers

Mail for a few large multi-carrier buildings often

includes the room or office number. By entering the

room number in the Building Number Field and an

abbreviation of the building's name in the Street Name

Field, this mail can be sorted directly to the appropriate

carriers rather than to a bin corresponding to the building.

This of course presumes operator knowledge of the multicarrier buildings stored in the memory.

4. 4. 2 Odd-Even Carriers

Some carriers deliver only to the odd or even side of

certain breaks. The present programming does not

differentiate between these two cases, but it could do so

if the special order concept were extended. A new S3

symbol could be placed before the break. Following the

break would be the bin numbers of the carriers serving

the odd and even sides of the break. The symbol would

initiate a test on the building number stored in the Building

Register. If it were odd, the first bin number would be

sent to the codewheel setter. If it were even, the second

would be sent.

An alternative method would be to enter in the memory

as exceptions the individual buildings composing the oddeven breaks.

-31-
4. 5 Summary

Serial programming is sufficiently flexible to accommodate a

variety of address forms if:

(1) A Test Suppression Instruction character is used in the

memory entries for a specific set of streets.

(2) Psuedo "streets" and "building numbers" are used for

the non-standard address forms. Table VI follows.

5. BINARY CODING AND DIRECTORY PREPARATION

5. Introduction

Three interdependent questions arise in the assignment of BCD

bit combinations to the alpha-numeric and special order characters:

(1) How many characters are required?

(2) How many unique bit combinations are necessary for their

specification?

(3) How many bits are required to specify each character, and

should all characters be composed of the same number of

bits?

5. 1 Characters Required

The characters required differ for local and outgoing mail. Local

mail utilizes:

(1) All digits and lower case alphabetics in the Building Number

Field.

(2) All digits (including l/2) and lower case alphabetics in the

Street Name Field.

(3) The lower case alphabetics s, a, r, p, d, c, 1, t, and y

in the Street Type Field.

(4) Four Section Designation symbols in the Section Field.

Outgoing mail requires:

(1) All lower case alphabetics and all upper case alphabetics

except E, H, J, Q, and U in the City Field.

(2) All lower case alphabetics in the State Field.

-32-
Address Type

(1) Standard Addresses:

(a) Complete

(b) Street type omitted

TABLE VI

Washington, D. C. Local Field Entries (Plan E- 1)

Building

Number Field

Street Name FieldStreet Type Field

Bldg. No

Bldg. No

1/

(c) Section Desig- Bldg. No.

nation omitted

Coded Street Name s, a, r, p, d, 1, c, t, or y Coded Street Name See 2/

Coded Street Name s, a, r, p, d, c,

1, t, or y

Section Designation Field

(Ne), (sE), (Sw), or (nW)

(Ne), (sE), (S w), or (nW)

See 3/

(2) Intersection Coded First

Street Name

* Coded Second Street Name

i Blank

(3) Boxes Box Number * b Blank Blank

(4) RFD Routes Route Number * r Blank Blank

(5) Named Destinations:

(a) Apartments

(b) Associations

(c) Clubs

(d) Companies

(e) Embassies &

Legations

(f) Hos pitals

(K) Hotels

(h) Office Bldgs. ' (i) Postal Stations

(.i) Schools

(k) Unions

(1) Miscellaneous

Coded

Name

4/

Blank Blank

1/

2/

3/

4/

The * symbol is here used as the End -of -Building -Number -Field Symbol.

If the Street Type is omitted, the letter s should be entered.

If the Section Designation is omitted, the (nW) designation should be entered.

Letters with room numbers for certain, as yet unspecified, multi-carrier buildings are coded to permit

sorting to individual carriers. The room number is entered in the Building Number Field; the coded

building name in the Street Name Field, and the letter b in the Street Type Field. The * symbol is used as before, and the Section Designation Field is left blank.
In addition to these, special instruction symbols are necessary.

The characters (approximately 70) are summarized below:

(1) Digits thru 9, and l/2,

(2) Lower case alphabetics a thru z,

(3) Upper case alphabetics A thru Z, except E, H, J, Q, and U,

(4) Section designations,

(5) Street symbol,

(6) Exception symbol,

(7) Break symbol,

(8) Hundreds -unit break symbol,

(9) Odd-even break symbol,

(10) Bin number symbol,

(11) End-of-Building Number Field symbol,

(does not appear in memory),

(12) Outgoing residue test instruction,

(13) Character test suppression instruction,

(14) Possibly more special symbols if differential

storage is used for outgoing programming.

5. 2 Unique Bit Combinations Required

A distinction exists between the unique characters and their

binary representations. The characters, to be effectively used by

human keyboard operators, must be unique. But some individual binary

combinations may be shared among characters with no loss in

information content, because of the uniqueness of the fields. The set

of incoming characters would bound this sharing since it includes the

set of outgoing characters. Some of the bit-sharing alternatives are:

(1) The character l/2 can be specified by an alphabetic character.

(2) Numbers can be used for the section designations.

(3) Any of the incoming characters not used in the outgoing

directory are usable as special order symbols in outgoing

programming (as long as local and outgoing mail are not

sorted simultaneously).

-34-
An allied reduction in the number of unique bit combinations may

be realized by using only three distinct special order symbols.

Combinations of these could then be interpreted as the remaining

symbols. It consequently appears that fewer than 64 unique bit,

combinations can adequately specify ail characters.

5. 3 Bits per Character

The question of how many unique characters are required is related

to whether or not all characters are specified by the same number of

bits. As has been discussed previously, information is read from the

drum as a series of pulses after instruction characters are interpreted.

This requires all instruction symbols to have an equal number of bits.

The orders then control the transfer and interpretation of the alphanumeric characters following them. Since alphabetic and numeric

characters can occur in any field, they must both have an equal number

of bits. Furthermore, alpha-numeric and instruction characters are

interspersed on the drum. Therefore, all characters must be specified

by the same number of bits.

A six information-bit code can specify all characters with a limited

amount of bit-configuration sharing, while a seven information-bit

code specifies all characters uniquely. The seven bit code also permits

characters to have meanings independent of their field position or mode

of programming.

5. 4 Data-Processing Equipment Considerations

The preceding general analysis has been independent of

considerations imposed by the data -processing equipment required for

memory preparation. The process of transferring and modifying the

presently used directories to the coded and ordered form to be fed into

the memory will be an extensive operation requiring standard data

processing equipment. The symbols used in this equipment do not

include the variety required by the programming. ±j For example, IBM

card punches have a vocabulary of only 47 symbols: the numerics

thru 9; alphabetics A-Z; and 11 punctuation and operational symbols (no

distinction is made between upper and lower case alphabetics).

Consequently, unique symbols do not exist for the 60 -odd characters

required. A reasonable solution using two symbols to specify certain

characters is suggested below.

—' Recently announced equipment may obviate this problem for filedirectory preparation. But the letter coding process necessitates

specifying many characters by two key-strokes if the coding keyboard is not to contain individual keys for all the characters

required.

-35-
5. 4. 1 Coding Vocabulary

The totality of characters necessitated by the coding

are:

(1) Digits 10

(2) Lower Case Alphabetic

s

26

(3) Upper Case Alphabetics 20

(4) Section Designations 4

(5) End-of-Building -Number

Field Symbol 1 crupper case alphabetics can be composed of two

characters: (1) a shift character; and (2) the desired

alphabetic character. Then, the coding keys required

for their specification are:

(1) Digits 10

(2) Lower Case Alphabetics 26

(3) Upper Case Alphabetic

Shift Key 1

(4) Section Designations 4

(5) End-of-Building Number

Field Key 1 42

This technique increases the length of coding

fields as follows:

-36-
Local Fields

Field

Building Number

End-of-Building -Number

Field Symbol

Characters

Up to 6

Street Name Up to 6

Street Type 1

Section Designation

1 Total:

1

Up to 15

Outgoing Fields

Field Characters

City Up to 6

State 2

Total: Up to 8

5. 4. 2 Memory Vocabulary

The characters used in the memory include all the

coding characters, except the End -of -Building -Number

Field symbol, together with the following instruction

characters:

( 1) Street Symbol:

(2) Break Symbol:

(3) Hundreds -Unit

Break Symbol:

Identifies the entry following it

as a street name, type, and

section.

Identifies the entry following it

as the upper limit of the first

break on a street.

Identifies the entry following it as the hundreds -unit differential

between two successive breaks

on a street.

-37-
2/

(4) Odd-Even Break Symbol: Identifies the entryfollowing it as a break

where odd and even

building numbers are

serviced by different

carriers.

Identifies the entry following it as an exceptional

building number.

Identifies the entry

following it as a bin

number.

Identifies the entry

following it as a city.

Initiates the performance

of the residue tests in the

Outgoing translation

program. •

Suppresses the performance of logical tests on

the character position it

occupies. This is used

only in the memory. For

example, it is entered in

the Section Designation

Field of streets appearing

in only one section and in

the Street Type Field of

street names having only

one type.

These instruction symbols (excluding (9)) may be

composed of two characters: an Instruction-Prefix symbol

common to all; and an Instruction-Suffix symbol (possibly

the lower-case alphabetics) specifying the particular

instruction.

(5) Exception Symbol:

(6) Bin Number Symbol:

(7) City Symbol:

(8) State Residue Symbol

(9) Character Test - Suppression Symbol:

—2/

' Residue tests can be performed as equality tests if suitable "cities"

are made up including the Character Test Suppression Symbols.

Then, both the S tate Residue and City Symbols are unnecessary.

-38-
As stated previously, the compound- symbol technique

arises from the vocabulary limitations of the coding keyboard and standard punched card-or-tape equipment used

for:

(1) Preparing the "source document" directory

file used to load the drum, and

(2) Updating the directory file.

However, the character -codes used internally by the

special-purpose computer can be arbitrary. Therefore,

all characters used by the computer can be specified by

single symbols if an input -output translation unit is

incorporated into the system. This unit would:

(1) Translate single and compound -symbol codes

of the file directory into single -symbol language

of the special -purpose computer during drum

loading, and

(2) Translate the computer language into file

directory language for drum checking and

debugging.

This alternative would reduce the memory space

needed by instructions and upper -case alphabetics. But

it would increase the space used by the remaining

characters since it requires a seven information -bit code

(the compound symbol technique uses a six information-bit

code). Assuming a parity bit is included, the local

directory space saving per item equals (14 + 7X) - (8 + 8X)r where X is the number of characters in an item. The

saving decreases rapidly and is zero at X equals 6

characters. Assuming the average local directory item

to be 3 characters, the average saving per item equals 3

bits, or a total memory saving of less than 10%. Assuming

the average item to be 4 characters, the total memory

saving is only 5%. Greater savings seem possible in the

outgoing directory since the compound symbol technique

increases the City Field to a possible maximum of 6

characters instead of 4. But if instruction characters are

used in the outgoing directory, the average city item should

be reducible to approximately 5 characters. Then the

saving will equal 3 bits per item, or less than 10%.

It does not appear that a translation unit can be justified

economically for full-serial storage. The memory saving is

negligible. Furthermore, the use of a non-standard

translation unit may significantly lower over -all system

reliability.

-39-
5. 5 Suggested Coding Keyboard

A possible coding keyboard using the compound character technique

is shown in Figure 3 (P43 ) and described below. The keyboard would be

used only for coding. File directories would be prepared with standard

card -punch machines.

Printing Keys

Number Key

1-10 Digits: 1-10

11-36 Lower Case Alphabetic s: a - z

37 - 40 Section Designations: Ne, sE,

nW, and Sw. These automatically actuate the forwarding

mechanism when depressed.

41 End-of-Building -Number - Field symbol

42, 43 Upper-Case Shifts: These are

printing characters which

together with lower case

alphabetics define their twocharacter upper -case

equivalents.

3/ Operational Keys—

44 Forward Key: releases coded

envelope and feeds in next one

for coding. Used only to

forward non- standardly

addressed Local letters

standardly addressed Local

letters are forwarded by the

Section Designation Symbols).

3/— Another operational key, valuable when successive letters have

the same destination, would be a duplicating key. When depressed,

it would imprint the stored coded fields of the previous address.

-40-
Number Key

4~7~

45 —

Outgoing Forward Key: Used

only to forward outgoing

letters. Also separates them

from local letters.

4/ 46 — (a) Nixie Key (upper case):

separates "nixie" (misaddressed or miscoded) mail.

(b) Uncancelled Key: separates

uncancelled mail.

4/ 47 — (a) Airmail, Special, and Foreign

Key (upper case): separates

these types of mail.

(b) 25 Key: separates Local

official mail.

5. 6 Directory Preparation

The preparation of the local and outgoing directories may be

described as a series of 7 steps:

(1) Adapting and ordering source documents to a usable form,

(2) Coding entries,

(3) Ordering entries alphabetically,

5/

(4) Deriving and inserting differential numbers —

(5) Inserting instruction symbols and bin numbers,

4/

5/

Keys 45 - 47 are "presort keys", i.e. , they separate their

associated types of mail, from the remainder of the letters, at the

coding station. This concept can be extended to keys 37-40. Then

local mail would leave the coding process sorted to section and

each section's mail could be individually sorted by the specialpurpose computer. This would not materially reduce memorysccess

time under the present memory system. But under a different

system, e.g. , a high-capacity drum feeding into a large core

working storage, significant savings could be effected.

These may not be used in the outgoing directory.

-41-
(6) Transcribing and editing entries to a form suitable as

input to memory drum,

(7) Preparing sub-directories,

(8) Preparing files and cross -files between original uncoded

entries and their alphabetically ordered coded counterparts

Directory preparation is directly related to the input-output

components of the system. These are discussed in the next section of

the report.

5. 7 Summary

Some salient characteristics of the binary coding problem have

been presented. These are discussed further in the next section of the

report. It is suggested that a 6 information-bit code be used and that

upper -case and instruction characters be specified by two characters.

A possible coding keyboard is also suggested.

-42-
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"6. DISCUSSION OF SYSTEM

6. Introduction

The report has been primarily concerned with the local and outgoing programs and their adaptability for accommodating special

address cases. This area is now discussed further and some

characteristics of the computer system presented.

6. 1 Programming

The flexibility necessitated by special types of addresses was

achieved by introducing special instruction symbols. But, it should be

noted that the program can treat all cases as standard breaks and

exceptions if a repetition of memory entries can be tolerated. zJ That

is, a tradeoff exists between increased memory space and a less

complex order structure. For example, addresses having their section

designation omitted were treated as NW by the coding operators. And

memory entries for all streets appearing in only one section were

entered with the Test Suppression Character as their section.

Consequently, error mail was sorted correctly if it were destined for:

(1) A NW street, or

(2) A street appearing in any one of the NE,SE, and SW

sections.

Error mail for streets appearing in more than one section including the

NW would then be sorted to the NW street (assuming the break limits

include the building number). Error mail for streets appearing in more

than one section excluding the NW would then be sorted to an error bin.

A similar procedure was used for addresses having their street types

omitted. Both these cases can be treated with identical results if the

entries previously entered with the Test Suppression Instruction are

duplicated in the memory and if the coding operator treats the

i/

In fact, all local exceptions can be treated as breaks if they are

entered as "sub-breaks" ., e.g., exception 1225 and upper break

limit 1399 on I S t. , NW can be stored as s^ i s (Nw)s, 1224s1225s 1399 instead of sj i s (Nw)s

2

1225s 1399. Consequently,

by duplicating the exception entries the s

? "(exception) instruction is

no longer necessary.

-44-
misaddressed mail as before. For example, Nicholas Ave. appears

only in the SE, but it would be entered in the memory as both Nicholas

Ave. , SE and Nicholas Ave. , NW with a corresponding duplication of

the break, exception, and bin number entries. The same procedure

would be used for street names having only "street" as their type.

Thus, incompletely addressed mail can be sorted to the same extent as now done manually by using either a special instruction or duplicating

entries.

Odd-even breaks were treated similarly. A special order was

entered before these entries to identify them. An alternative method is

to enter all buildings in these breaks as exceptions together with their

bin numbers. This technique is also applicable to the non-hundreds unit

break limits. Again, successive buildings can be treated as exceptions

until the hundred-unit building is reached. Then the regular differential

break procedure can be resumed.

The programming comparison tests were, for clarification purposes,

described as taking place in 4 "local" registers and 2 "outgoing"

registers:

(1) Street Register

(2) Temporary Street Register

(3) Building Number Register

(4) Temporary Building Number Register

(5) City Register

(6) Temporary City Register

But this multiplicity of registers is unnecessary. Cities can be stored

as "exceptions" and residue cities as "breaks" on their state "streets"

thus obviating the need for (5) and (6) zJ . Furthermore, the local

comparisons on street and building number are performed serially.

2/ And also permitting mixed local and outgoing mail to be sorted

simultaneously. If this is done, however, some differentiation is

required between local and outgoing destinations having identical

short codes. This might be accomplished by having the Outgoing

Forward Key on the coding keyboard automatically imprint an

additional character. The outgoing memory short codes would

then be stored including the additional character. This would allow

duplication between local and outgoing short codes memorized by

the coding operator while yielding operationally distinct codes.

•45-
Thus the two temporary registers may be replaceable by a single

register holding the entries successively read from the memory.

6. 2 Memory

The translation from coded addresses to bin numbers is

performed by two testing routines:

(1) Channel selection (predirectory "table look-up")

(2) Channel search (directory search)

Several alternative storage patterns for the drum information are now

presented. All assume the predirectory is stored on the same drum

as the directory.

6. 2. 1 Serial Predirectory and Directory

The first method is shown in Figure 4 (P52). An m

channel predirectory and an n channel directory are

stored on an m + n channel drum. Randomly arriving

coded addresses are compared with the first predirectory

channel, which stores the greatest entries in the first

l/m channels of the directory. ±f If the first channel

includes the directory channel entry (and its channel

number), reading is switched to the appropriate channel.

If the first channel did not include the appropriate entry,

reading is successively switched to the remaining m-1

channels until the correct one is located. Predirectory

access time is therefore 0.5m drum revolutions where m

may differ for local and outgoing predirectories.

Directory access though, is complicated by the outgoing

residue entries stored on certain channels. Since

directory entry is random the stored residue test entries

will result in appreciable missorting. Therefore, either

reading should always commence at one point on all

channels (increasing access time by 0.5), or the residue

test output should be suppressed until the drum has made

a complete revolution without an exact match occurring.

3/ If reading is always begun at one point on the drum (thus increasing access time by l/2 drum revolution) the correct entry is

specified when the comparison test results change from < to >.

If entry is random, the channel is specified when test outputs

change from < to > or from > to < . In either case the

channel numbers associated with the entries must be offset by one

entry, e.g. , channel number for entry i is stored after entry

i+1. (An alternative is to store the channel number before its

entry and hold it in a temporary storage register while its entry

is tested)

.

46-
Predirectory and directory searches are simultaneously

performable on successive addresses. Thus access time per

address reduces to 0. 5m. But this is unacceptably high, e.g.

a million bit 400 channel drum requires approximately 8

predirectory channels or 4 drum revolutions access time.

6. 2. 2 Serial Directories, Predirectory Channel Selection

Access times are reducible to a single drum revolution

if the predirectory concept is extended to the predirectory

itself as shown in Figure 5 (P53). The greatest entry in

each predirectory channel is listed at the beginning of each

channel. Thes e key entries (or the channel reading heads)

are successively offset by a constant distance. Entering

coded addresses are compared with these key entries until

their channel if found. _/ Predirectory access time is then

0.5 + 0.25 0/tt drum revolutions. The latter term should

be negligible in comparison to the first. Directory reading

can then always begin from line bb 1 thus precluding any

residue test output suppression procedures. Directory

access time is 0. 5 drum revolutions assuming entries are

stored in the shaded area of Figure 5. But if entries are

stored there simultaneous searches on two channels will

occasionally occur. Therefore a duplication of directory or

predirectory comparator circuitry or some operational

interchangeability between predirectory and directory

comparator circuitry is required. This complication can be

bypassed if angle is negligible. W Then the shaded area

of Figure 5 is also negligible and can remain empty. Thus

all channels end at line aa' and simultaneous comparisons

never occur.

A further extension of the predirectory concept would

be to specify not only the directory channel, but also the

sector within that channel. Figure 6 is an example of a

4 sector per channel system which decreases directory

access time by a factor of 4. A modulo 4 counter is

increased by unity every 0. 25 revolutions of the drum.

Consequently the modulo 4 sum of the channel sector read

from the predirectory and the counter value specifies the

4/ The key entries could just as well be the lowest entry in each

channel and switching performed to the previous channel as soon as

the key entry becomes > than the entering address entry.

—f Angle 6 can also be reduced by: (1) Revising the placement of

the key entries and increasing predirectory comparator circuitry

and/or; (2) Storing the key entries serially, but the characters

comprising the entries, in parallel.

-47-
reading head to be activated. This would increase the

predirectory by a factor of slightly more than 4 and would

require four times as many directory reading heads and

might also require more complex predirectory comparator

circuitry.

6.2.3 Serial Directory, Integral Predirectory

As shown in Figure 7 (P55) the predirectory channel

selector technique can be us ed within the directory thus

making a separate predirectory unnecessary. The greatest

entries are offset listed. Then a predirectory search is.

performed on the helical path traced by the key words. _/

When the correct channel is found, directory reading begins

immediately. JJ Average channel selection and reading times

are then each 0. 5 drum revolutions. But since predirectory

channel selection tests are constrained to begin on line aa',

operational access time is either 1 or 2 drum revolutions;

and average access time is therefore 1. 5 drum revolutions.

This can be reduced to 1. drum revolutions by permitting

random entry and duplicating comparator circuits thus

allowing simultaneous predirectory and directory searches.

6.2.4 Parallel Storage, Integral Predirectory

As has been seen, the many predirectory tests

appreciably complicate the comparator circuitry. This

can be mitigated by storing entries in parallel rather than

serially, as shown in Figure 8 (P56). Key words, in

parallel, are still used. The number of predirectory tests

is then reduced by a factor equal to the product of the number

of characters per entry and the number of bits per

character. 2/Angle 6 is therefore negligible and the shaded

area of Figure 8 can be kept as slack space. Access time,

assuming reading always begins at line aa' is then fixed at

1. drum revolutions.

Parallel storage's simplicity results from its use of

fixed-length fields and simultaneous testing on all characters

within a field. A possible parallel memory layout is shown

—' As many independent predirectory comparator circuits as there are

helical loops are therefore required.

7/— Only one directory comparator circuit is required if initial reading

always begins on line aa' after the previous channel search is

completed.

8/— Sets of channels are sought rather than individual channels.

-48-
in Table VII (P 51). All local and outgoing entries are

treated as streets, exceptions, and breaks. 9/ While

conceptually simpler than serial storage, parallel

storage requires much more memory space since the

fields are fixed to accommodate the longest entries. ±£j

It may therefore be feasible to use a code - trans lation

unit and a 7 rather than 6 information bit code.

Table VII assumes a 7 information -bit code and fixes

each entry at 6 channels. A 6 information -bit code would

necessitate storing instructions and upper-case alphabetics

as compound characters thus increasing field length and

memory size by 33. 3%.

The conceptual and operational simplicity of parallel

storage and programming suggest that they may be

feasible alternatives to the s erial methods that have been

presented. No separate predirectory is required and all

comparison tests are done in a single comparator circuit.

Furthermore, access time is fixed at X. drum revolutions

thus simplifying the program timing and residue

operations. ±1/

6. 3 Input -Output Considerations

The system's input and output operations are:

(1) File directory loading

(2) Coded Address read-in

(3) Checking and debugging read-out

(4) Bin number read-out.

2/

10/

11/

The differential storage procedure of serial programming is no

longer applicable since field lengths are fixed.

A local file directory of 3500 streets, 7500 breaks and 7500

exceptions (including special address forms) would require

approximately 1. 5 million bits (assuming each character to be 8

bits long). A 1. 5 million bit drum could store approximately

12,000 cities. A serial storage system having the same 1.0 drum

revolutions access time would require only about 3/4 as much

memory space to store the same number of entries. But as has

been seen it would require duplication of comparator circuitry and

a much more complex method of channel selection.

It is assumed that a 12 character entry buffer is used so that an

address is always available as soon as line aa' is reached.

-49-
Since files will be prepared on punched cards, (1) can be performed by

a punched card reader, or a paper tape reader if cards are first

converted to tape. If parallel drum storage is used, a translation unit

may be required for translating the characters into 7 rather than 6

information-bit codes. If possible, the bit configurations produced by

the coding keyboard should be identical to those used internally within

the computer, 12/ Thus the translating unit would be used only during

directory file loading. —' An additional unit may be required for (3)

to translate the internal codes to a form acceptable to the output medium,

e.g. , inquiry typewriter. It appears therefore, that an extended

standard computer code should be used since an extra bit position could

be readily added and deleted thus simplifying the specification and

reading of instructions and upper case alphabetics. A fully arithmetic

code might also simplify (4) since bin numbers can be specified by 3

"numbers" yielding all possible combinations of 12 bits.

6. 4 Summary

Some major considerations of code sorting have been presented.

Both serial and parallel programming are discussed in relation to the

memory layout and their flexibility for accommodating standard and

special address forms.

—12/

' This is readily achievable if upper case alphabetics differ from

their lower case counterparts by a single constant bit. Then, the

shift key could imprint that bit rather than a separate character.

13/ Parallel storage would increas e the loading problem since all

entries will have to be written linearly across channels rather

than serially along a single channel.

-50-
TABLE VII

Parallel Stora ge Entries

Loca L

x

l X

2

X

3

x

4 x

5

X

6

Street i

x

l X

2

X

3

X

4 X

5

S

l Exception

- X

2

X

3

X

4 x

5

S 3

Bin Number

x

l X

2

x

3

X

4

X

5

S

2 Upper Break Limit

! X

2

x

3

x

4 x

5

S

3

Bin Number

x

l x2

x

3

x

4 x

5

s 2 Upper Break Limit

i

x

2

x

3

x

4 x

5

•

S 3

•

Bin Number

i x

l X

2

X

3

•

x

4 x

5

•

x

6

Street i + 1

Outgoing

i

- - - x

5 HS State j ("Street")

- x

2

X

3

x

4 x

5

s

i City ("Exception")

1 X

2

X

3

x

4 X

5

s 3

Bin Number

- X

2

X

3

x

4

X

5

s

l City ("Exception")

1 x

2

X

3

x

4 X

5

s 3Bin Number

i

• • • • •

USCQMM—DC

("upper

a to 1 residue break

limit")

m to z residue ("upper

break

limit")

-51
2 3 /ttl23 K

a.

k

PR ED I RECTORYf

DIRECTORY -J

AVERAGE ACCESS TIME: 0.5 DRUM REVOLUTIONS

(NOT TO SCALE)

FIGURE 4- SERIAL PREDIRECTORY AND DIRECTORY

AVERAGE ACCESS TIME: 1.0 DRUM REVOLUTIONS

(ASSUMING IS NEGLEGIBLE)

(NOT TO SCALE)

FIGURE 5. SERIAL DIRECTORIES , PREDIRECTORY CHANNEL SELECTION
HEAD 00

HEAD HEAD 01

COUNTER | |

|

TIME COUNTER

00

dr/4 01

dr/2 10

3 dr/4 II

00

COUNTER VALUE

01 10

rr

ocn>

UJ

rr

00

10

00 01 10 II

01 10 II 00

10 1

1

00 01

II 00 01 10

FIGURE 6. SECTOR SPECIFICATIONS
AVERAGE ACCESS TIME : 1.5 DRUM REVOLUTIONS

(NOT TO SCALE)

FIGURE 7. SERIAL DIRECTORY, INTEGRAL PREDIRECTORY

'/////////////

ACCESS TIME: 1.0 DRUM REVOLUTIONS (FIXED)

(NOT TO SCALE)

FIGURE 8. PARALLEL STORAGE, INTEGRAL PREDIRECTORY
U.S. DEPARTMENT OF COMMERCE

Frederick H. Mueller, Secretary NATIONAL BUREAU OF STANDARDS

A. V. A si in. Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its major laboratories in Washington, D.C., and

Boulder, Colorado, is suggested in the following listing of the divisions and sections engaged in technical work.

In general, each section carries out specialized research, development, and engineering in the field indicated bj

its title. A brief description of the activities, and of the resultant publications, appears on the inside of the front cover. WASHINGTON, D.C.

Electricity and Electronics. Resistance and Reactance. Electron Devices. Electrical Instruments. Magnetic Measurements. Dielectrics. Engineering Electronics. Electronic Instrumentation. Electrochemistry.

Optics and Metrology. Photometry and Colorimetry. Photographic Technology. Length. Engineering

Metrology.

Heat. Temperature Physics. Thermodynamics. Cryogenic Physics. Rheology. Molecular Kinetics. Free

Radicals Research. Atomic and Radiation Physics. Spectroscopy. Radiometry. Mass Spectrometry. Solid State Physics. Electron Physics. Atomic Physics. Neutron Physics. Radiation Theory. Radioactivity. X-rays. High

Energy Radiation. Nucleonic Instrumentation. Radiological Equipment.

Chemistry. Organic Coatings. Surface Chemistry. Organic Chemistry. Analytical Chemistry. Inorganic

Chemistry. Electrodeposition. Molecular Structure and Properties of Gases. Physical Chemistry. Thermochemistry. Spectrochemistry. Pure Substances.

Mechanics. Sound. Mechanical Instruments. Fluid Mechanics. Engineering Mechanics. Mass and Scale. Capacity, Density, and Fluid Meters. Combustion Controls.

Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Poly- mer Structure. Plastics. Dental Research.

Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion. Metal

Physics.

Mineral Products. Engineering Ceramics. Glass. Refractories. Enameled Metals. Constitution and Microstructure.

Building Technology. Structural Engineering. Fire Protection. Air Conditioning, Heating, and Refrigeration. Floor, Roof, and Wall Coverings. Codes and Safely Standards. Heat Transfer. Concreting Materials.

Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics.

Data Processing Systems. SEAC Engineering Group. Components and Techniques. Digital Circuitry.

Digital Systems. Analog Systems. Application Engineering.

• Office of Basic Instrumentation. • Office of Weights and Measures. BOULDER, COLORADO

Cryogenic Engineering. Cryogenic Equipment. Cryogenic Processes. Properties of Materials. Gas Liquefaction. Radio Propagation Physics. Upper Atmosphere Research. Ionospheric Research. Regular Propagation

Services. Sun-Earth Relationships. VHF Research. Radio Warning Services. Airglow and Aurora. Radio

Astronomy and Arctic Propagation.

Radio Propagation Engineering. Data Reduction Instrumentation. Modulation Research. Radio Noise. Tropospheric Measurements. Tropospheric Analysis. Propagation Obstacles Engineering. Radio-Meteorology. Lower Atmosphere Physics.

Radio Standards. High Frequency Electrical Standards. Radio Broadcast Service. High Frequency Impedance Standards. Electronic Calibration Center. Microwave Physics. Microwave Circuit Standards. Radio Communication and Systems. Low Frequency and Very Low Frequency Research. High Fre- quency and Very High Frequency Research. Ultra High Frequency and Super High Frequency Research. Modulation Research. Antenna Research-. Navigation Systems. Systems Analysis. Field Operations.