Will The Grand Master Of Disk Controllers step foreward?

From: Richard Erlacher <edick_at_idcomm.com>
Date: Fri Apr 16 17:49:52 1999

I thought it would (mmaybe) be helpful to point out that WD made several
similarly designated controllers during the period when the
8"-drive-compatible models were available. The WD 1000 series members which
used the 8X300 microcontroller used a different command set or register
organization, which was, IIRC inverted in some sense, i.e. either the
register order was the inverse of the one on the LSI version, or the
commands were the complement of the ones the LSI version (designated
1000-05, 1000-08, the latter of which I doubt was ever shipped) As several
folks have indicated some of these controllers had both the 50-pin connector
for the 8-inch drives' data cable, and the 34-pin connector for the 5-1/4"
drives' data cable.

What's not entirely obvious with the LSI controllers' jumper layout,
characterized in the documents only as a means for disconnecting biasing
voltages from the PLL circuitry during calibration, is that if one removes
the shorting plugs from some models, again depending on the version, a
jumper then will suffice to bypass the PLL circuitry, thereby allowing the
use of the clock already available from those drives which provide it on the
data connector. If this clock is fed to the circuitry downstream from the
PLL, the controller needs no further modification aside from changing the 4x
crystal, shipped at 20 MHz, to one at 17.36 MHz, which is 4x the standard
rate for 8" drives. That means that an oscillator and a single jumper is
all that's necessary to convert some of these boards from 5.25" to 8".

Persons wishing to use 8" HDD's should BE CAREFUL with the negative bias
supply. Just like some 8" FDD's, some of these drives have on-board
regulators for the negative supply, hence will only work if they're fed a
nominally -12 V dc source (actually anything greater than -8 vdc and not
damaging to the circuitry will be ok) since there's an on-board regulator.
A bypass jumper is usually provided, as some
drives will be used with supplies designed for drives without the on-board
regulator, therefore demanding -5V dc.

If this bias supply is not correct, either due to the lack of compatible
supply and regulator, or because -5 is being fed to the regulator, the drive
will not work. If -12 is fed to the drives which have no regulator, the
head interface circuits and probably the data conditioning circuits will be
damaged. BE CAREFUL!

I didn't learn about this over a beer after work, or by reading an article
in a magazine . . . 'nuff said???

Dick


Dick
-----Original Message-----
From: Don Maslin <donm_at_cts.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Friday, April 16, 1999 4:14 PM
Subject: Re: Will The Grand Master Of Disk Controllers step foreward?


>On 16 Apr 1999, Eric Smith wrote:
>
>> > Specifically the WD-1000-5 disk controller. These are the ones that
>> [...]
>> > If you are intimately familiar with this legendary interface, I would
>> > like to hear from you. I need to figure out how to modify it for 8"
>> > harddrives.
>>
>> Regrettably I no longer have the manual or schematics for these, so a lot
>> of this is from memory.
>>
>> The WD1000-5 was the WD1000 repackaged on an 8" * 5.75" board, to match
the
>> form factor of 5.25" drives.
>>
>> The original WD1000 and WD1001 had both 34 and 50 pin drive control
>> connectors. I'm guessing that the WD1000-5 left the 50 pin connector
out.
>> However, you only need to scramble the pins appropriately, as the actual
>> signals are the same. All odd pins are ground on both connectors; the
others
>> should map thusly:
>>
>> 34-pin 50-pin signal
>>
>> 2 2 *RWC reduced write current
>> 4 4 *HS2 head select 2
>> 6 40 *WG write gate
>> 8 8 *SC seek complete
>> 10 42 *TK0 track 0
>> 12 44 *WF write fault
>> 14 14 *HS0 head select 0
>> 16 NC
>> 18 18 *HS1 head select 1
>> 20 20 *IDX index
>> 22 22 *RDY ready
>> 24 36 *STEP
>> 26 26 *DS1 drive select 1
>> 28 28 *DS2 drive select 2
>> 30 30 *DS3 drive select 3
>> 32 32 *DS4 drive select 4
>> 34 34 *DIR step direction (in when asserted)
>>
>> The radial data connectors are the same for both drive sizes.
>>
>> The bigger problem is that 8-inch drives used a data rate of 4.34 Mbps
rather
>> than 5 Mbps. I seem to recall that the WD1000 had a jumper setting for
this.
>> If they removed the 50-pin drive control connector, they probably also
removed
>> the jumper and supporting circuitry.
>>
>> > Also, does anyone have docs for the Quantum Q-2040 8"
>> > Winchester? I dunno what kind of power to feed it (24v sounds correct,
>> > but I seem to recall it used 110vac also!), and so on.
>>
>> No data here, but almost certainly not 110 VAC. Probably 24V AC and 5V
DC.
>
>Sorry Eric, but the spin motor is identical to the ones used in the
>Shugart SA80n series - 120 VAC 60Hz 1.6 Amp. The rest of the power
>requirements come in through a 6-pin connector, also identical to the
>Shugart, so I would assume +5 VDC, -5 VDC (maybe), and 24 VDC. Probably
>to the same pinout as the Shugart.
>
>> You *might* be able to get a Q2040 to run at 5 Mbps, but I've never
>> personally seen it done.
>
>I have a hazy recollection of running one on a latter day HDC to view data
>contents, but the details elude me now.
> - don
>
>
Received on Fri Apr 16 1999 - 17:49:52 BST