From: lowen@lorc.UUCP (Lamar Owen)
Newsgroups: alt.folklore.computers,comp.unix.misc
Subject: Re: Unix Roots of DOS?
Date: Wed, 22 Jul 92 13:30:03 EDT
Organization: LORC Enterprises

allbery@NCoast.ORG (Brandon S. Allbery KF8NH) writes:
> As quoted from <eFmyNB4w164w@lorc.UUCP> by lowen@lorc.UUCP (Lamar Owen):

Wow! A quote!

> +---------------
> | On page 7 of "DOS Power Tolls" (A Bantam Book...The PC Magazine book is not
> >-------------------------^^^^^ Freudian slip?  :-)

Yep... Slip of the tongue...in cheek. :-)

> |file management and directory system.  CP/M had dealt with large disks by
> |splitting (or partitioning) them evenly into smaller ones, an inelegant and
> |inefficient solution.  But UNIX, an operating system developed by the phone
> |company, could handle vast volumes of files with relative style and ease.
> +---------------
> 
> The interesting thing being that the CP/M-80 world had its own solution,
> namely ZCPR... which used the TOPS-10 (or possibly Tenex / TOPS-20)
> hierarchical filename notation.  (Considering how klunky DOS is, it would
> probably have been appropriate.  :-)

And, considering how klunky ZCPR is.... it WAS appropriate!

The folklore side of this is staggeringly lore-ish:

The ZCPR parti-bigots have appropriately named their newest, hotest Z280 16-bit
machines (yes, Virginia! There IS a 16-bit Z80! Long live the Z280!!!) after
how they felt about MSDOS--thus, you get the Grudge, Dos-Killer, and Vengeance
Z280 motherboards that run ZCPR3.  BTW, ZCPR could stand for "Zilog Cardio-
Pulmonary Resuscitation", if one wanted to be snide...  Some of these Z280
beasts (and, with 16 MB RAM capability, with the Z280's multitasking VM
support and MMU system, 256 byte cache, and clock-multiplier design (more in
a moment on the Z280 clock-multiplier system), 16 and 32 bit instructions,
over 20 addressing modes, including a handy beast called "Program-Counter
Relative" (BTW, the VAX ain't got one thing on THIS chip's CISCiness!!!) and
over 2000 instruction codes (not as regular as a VAX or 68K, but every bit
as CISCy!), they do qualify as "beasts") even will allow ISA-bus peripherals
to be used (16-bit bus, of course--Zilog's Z-BUS technology at work). (Don't
you just *LOVE* long, multi-parenthetical, multithreaded sentences??)

Now, the fun part: since DOS was already around, some of these ZCPR people
decided to make an un-DOS 7up style system--thus, since DOS, to a CP/M
person, looks just like Unix, they couldn't possibly use ANY Unix constructs.
So, they got ahold of the syntax of the next most popular hackish OS (TOPS-10/
Tenex/Twenex (Ok, ok, TOPS-20...Sheesh)) and canabalized it.  The result is the
present day ZCPR3, which, to a TOPS wizard is just as perverse a mutt as DOS
is to Unix weenies (like myself :-))

Any time you combine CP/M with a real OS (donning asbestos longjohns...), you
get a real mutt.

Yes, I used CP/M, and own three (oops, forgot the Altos and Onyx systems...) 
FIVE different implementations of CP/M (Montezuma's TRS-80 Model 4 CP/M 2.2;
Pickles and Trout CP/M for the TRS-80 Model II; Radio Shack CP/M 3.0 for the
Model 4; Altos CP/M; and Onyx CP/M).  I *DO NOT EVER* want to go back to the
days when all I used was CP/M and TRSDOS!  Unix is MUCH better...  However,
I have yet to find a good Unix for the Z280...which is my favorite chip. So,
I struggle along with a 68030 machine (which is probably 10 to 15 times
faster than the Z280 machines are--hey, but I don't care.  The 68K instruction
set just ain't as beautiful--er--crufty--as the Z280's)

Now, about the Z280 clock-multiplier: built into the Z280 is a three-speed
bus unit (stick-shift transmission, if you will).  The bus unit, depending 
upon the boot register image load during RESET, will either run 1x, .5x, or
.25x the CPU clock.  So, you could get a Z280 running at 16Mhz, boot load
the proper bits in the boot register during RESET, and have the bus running
at 4 Mhz.  Intel's DX2 designs are behind the times!

For those history buffs (and for the "Great Microprocessors" list maintainer,
the Z280 first came out in July of 1987.  A bug was found and fixed in early 
'88

> ++Brandon
> -- 
> Brandon S. Allbery, KF8NH [44.70.4.88]: allbery@NCoast.ORG, bsa@telotech.com
> Senior Programmer, Telotech, Inc. (if I may call myself that...)


Lamar Owen, Systems Consultant, GE Lighting Systems, Hendersonville, NC
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