24 Jan
2011
24 Jan
'11
7:52 a.m.
Hi guys,
I've just bought myself another Big, Heavy Hard Drive... This time, it's
a CDC/Magnetic Peripherals 94205-51, 42MB MFM, 5.25in Half Height,
(though it looks a lot bigger than 5.25in), with an ST412 style
interface. I also snagged a Western Digital WD1003-WA2 MFM controller,
and a full set of cables. Whether I'll be able to fit the WD1003 into
the 386 PC remains to be seen: if it will fit, it'll be a tight squeeze.
As for condition, there are few bad tracks marked on the drive label,
but it spins, appears to pass the seek test, and unlocks the actuator
successfully (there's a loud CLACK just before the seek test starts).
Question: Does anyone have an OEM Manual or similar for this drive?
There's a manual for the Wren II ESDI on Bitsavers, but apparently not
for this drive. I can work from the ST506 spec if need be, but the
original manual would be nice to have.
For the pathologically curious: I'm building an ST412 adapter for the
DiscFerret (details will, of course, be published "when it's done"). It
turns out I've over-engineered the DiscFerret's PSU quite significantly:
even with the 20W load the Wren places on the power rails, the PSU
doesn't even break a sweat...
I'll probably end up adding a 4-way DIP switch to set the "drive select"
value, and run it off of the Ferret's DS0. That leaves me with DS1 to
use for head-switching, along with a few other I/Os which are on the
Shugart floppy interface but not the ST506 Control connector. MFM
RDAT/WDAT will be fed to the High Speed I/O connector for obvious
reasons :)
I'm planning on replacing the "recommended" 75157/75158 "dual
differential driver/receiver" pair with a 26LS31/26LS32 quad diff RX/TX
pair on the grounds that:
* The 26LS parts are cheaper by about a factor of 3
* the 26LS parts seem to be easier to find (higher stock levels at
Farnell and Digikey when I last checked).
Anyone reckon I'm likely to have any problems with this substitution?
Thanks,
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/