From: roozemaa@dutiws.twi.tudelft.nl (Peter.Roozemaal.IS-assistent)
Subject: ST506 floppies/harddisks
Organization: Delft University of Technology
Date: Thu, 17 Dec 1992 16:32:08 GMT

I post this article on behave of Olaf Zevenboom who, due to serious
undergraduation doesn't have net access. Please send replies to the
above address and NOT to the address supplied in the signature
----------------------------------------------------------------------

Open letter to Acorn Computers Technical Department
===================================================

Problem: connecting a harddisk and two floppydrives to my Acorn Archimedes
         A410/1

The harddisk is a ST506 type drive. It is a ST1100 or in full:
Seagate Imprimis Swift ST1100.

The floppydrives are both 3.5 Inch and should be connected to my AEDA
drivebuffer made and sold by Technomatic. The drives are: 
(HD) Teac   : FD-135HFN-419-U
(DD) YeData : YD 645C

Specifications:
A410/1 : upgraded to 4mb, temperature dependent fan, AEDA drivebuffer
         The drivebuffer can controle four drives. My BASF 5.25 inch drive
         works correctly with it, as did the Cannon (5.25 inch) drive I once
         owned. As a reply to my letter with questions they send me a
         catalogue with pricelist. You can imagine I won't spend another 30
         pounds at Technomatic's! Unable to give your own product technical
         support? Fabulous service guys!
ST1100 : 3.5 inch ST506 drive (83.75 mb formatted). 1072 cylinders,
         10 heads, autoparking


The harddisk problem:
---------------------
    When one tries to format a ST506 harddisk using the RISC-OS 3.10 format
program one will be warned by the program if the disk has more than 8 heads.
The program gives the following message:
WARNING - since the drive has more than 8 heads, the computer's 'low write
          current/head select 3' links may need changing. -
     This warning is omitted in the RISC-OS 2.00 formatter, but the effect is
the same!
     This message is nowhere mentioned in manuals, etc. I do not have
PCB-schematics of my A410/1 so I cannot check which links are meant. I
suppose links LK12 & 13, but I am not sure.
     When I continue with formatting without changing any links I get
discerror 16 (Sector ID has not been found?). Formatting with 8 heads is ok,
but 67mb out of 83mb is not entirely satisfactory. Besides when one tries to
verify the drive using the verify-menu option of the desktop-environment or
directly from the CLI (command line interpreter) ADFS starts complaining:
'Defect found at 000x0000' where x starts at 1 and increases by 1 at a time.
The drive is ok (writing directories/files, loading,saving, *map & * compact
worked fine). So why the errors. Neither the formatter is complaining.
     The guy I bought the drive from said I should set 'Precompensation
Cylinder', 'Parking Cylinder' and 'Low current cylinder' to 1072, because
these options should not be used with my drive. Besides this I should remark
that the cables he gave me are cut: wire 8 of the thin-cable (20 wires) and
wire 3 of the thick-cable (34 wires). None of these cables are 'twisted'.
QUESTIONS:
     - how can I get the best out of my drive (ie highest capacity)
     - why does *verify behave strangely
     - why are the wires cut and is this ok. What are the meanings of those
       wires?

The floppydrive problems:
-------------------------
    No matter which link combinations on the drives I try I can not get them
to work. I bought the Teac-drive at the dump, without a frontplate and
instructions on cabling, etc. I know I can (unfortunately) not use it in
HD-mode, but it should be usable as an ordinary DD drive. I bought the
YeData drive new at a sell-out. I have been able to get the Teac drive
working correctly with the Master128/512 of a friend of mine. Changing the
drive-links has an effect on the drive spin-ups and the drive-led, but a
proper catalogue or format is impossible.
    An A4-sheet was included with the sealed YeData drive stating the
drivecable should be 'twisted' (wires 10-16 inverted). The links of both
drives got different names (except the obvious DS (drive select)). Why does
every manufacturer thinks he knows things better?
    The standard documentation of the AEDA-interface consists of two
A4-sheets. It shows you how to configure AEDA for several combinations of
internal/external drive(s). Using 5 links (as standard not made) the
following options can be set (I quote):
- Data Cable Power Supply: if your drive can be powered through the data
  cable, make links 2 and 4 using two short pieces of wires.
- External Disc Eject: If your external disc drive has the facility for disc
  eject signal (as the Archimedes internal drive), make link 1.
- In-Use signal: make link 3
- Disc Present: link 5 when made will enable this signal.
This AEDA (Archimedes External Disc Drive Adaptor) sells currently at 10
pounds. When one buys the most expensive drivebuffer (30 quid) (at the time)
one expects one gets jumper-facilities to (un)make links and proper service!
    The names of the links on the drives are:
TEAC   : MS, ds0-3, IR, RY, DC , FG.
YEDATA : ds0-3, TM or TW, TD, MR, OP (0P?), P1, P2, P3.
The yedata drive links MR, OP and P1, P2 can be mode by jumpers (and of
course the ds-links).
QUESTION: I have a PSU, an old Master Compact-case and a couple of drives.
          How can I make them work?


All reactions varying from comments, tips to complete solutions are mostly
welcome. I can be contacted at:

Olaf Zevenboom

roozemaa@dutiws.twi.tudelft.nl

-- 
--- Peter W. Roozemaal --- Email: witaroo@dutinfh.twi.tudelft.nl --------------
-------------------------- Smail: Geitenkamp 45 -------------------------------
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