I recently received a PCjr add-on which is so unusual, it felt like
Christmas. But as always, it needs a little TLC.
This is an expansion chassis made by an outfit called "Legacy
Technology" in Nebraska in the mid to late 80s. The interesting part of
the chassis is a hard drive controller card and hard drive. PCjrs only
had hard drives if you bought a 3rd party controller, and they were all
pretty hackish.
The drive is a 20MB Teac SD-520U and it is very flakey - I am getting
data corruption almost all of the time. The corruption seems random;
this drive might just be tired.
I've low level formatted the drive twice. The controller BIOS supports
INT 13, Function 7 (Low Level Format). It's not helping.
Since the drive is probably not usable, I'm trying to figure out how to
substitute in another drive. Examination of the BIOS extension shows
that the controller supports 3 types of 20MB drives and 1 type of 10MB
drive. I have 10MB drives that I can use, but not another 20MB drive.
This is an XT class controller so I'm expecting to find some jumpers to
set the drive type, but they are eluding me.
The controller is actually a two part affair - A small amount of logic
with the system BIOS extension on it, and then a WD1002-HDD board. The
WD1002-HDD board mounts to the underside of the hard drive and then
connects to the hard drive using the familiar 34+20 wire ribbon cables.
It looks like it is capable of controlling three separate drives; it
only has one 34 pin connector, but it has three 20 pin headers, one of
which is in use.
Does anybody have docs for the WD1002-HDD? If so, where do I find the
drive type jumpers on the board?
If I can't figure the controllers out I'm going to be looking for a
similar drive. I suspect the trusty ST-225 works - the geometry is the
same.
Regards,
Mike
We in MARCH are selling the following IMSAI 8080:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270739896050
Proceeds for this system are NOT going to our club, but rather to the widow of a local computer reseller who died in an industrial accident recently. Our club was asked to fix up the computer and sell it on her behalf.
- Evan Koblentz and Bill Degnan
I have encountered an old 14" disk drive - it looks like it is
probably a clone of an IBM 2314. It does not look like a 2314 at all
(it is plain blue box with, that sort of looks like a 2311, but with
more heads), and no tag at all. The drive interface uses that goofy
connector that the late 60s IBM drives standardized on, for talking to
the control units. The boards all have "CMS" stamped on them. Any
ideas? Was CMS, whoever they were, one of the early clone companies?
--
Will
On Thu, Apr 21, 2011 at 2:47 PM, Fred Cisin <cisin at xenosoft.com> wrote:
> On Thu, 21 Apr 2011, Brian Lanning wrote:
>> My mom was a secretary. ?She had an IBM selectric. ?World's loudest
>> typewriter. ?She could type 90wpm on that thing. ?Oh man, what a
>> sound. It sat on a foam mat to try to absorb some of the vibration. ?I
>> used that for my papers until I got an original IBM 5150 and my school
>> got a much of Apple 2Es.
>
> Rated top speed for the mechanism was 14.8 characters per second (about
> 150 WPM). ?But a 150 WPM typist (yes, I've met some!) would have bursts
> substantially higher, and selectrics would come apart.
I do not know precisely how fast my mother could type, but her
Selectric sounded like a machine gun when she got going. She never
had one "fly apart", but she did wear out more than one unit from
8-10-hour-days of multi-page-carbon-set production work (final copies
of court transcripts). She was paid by the page, so long stretches of
error-free typing was the only way to make a decent wage.
At one point in the early 1980s, her machine broke and she took it to
a new repair shop in town. The tech was puzzled at the wear he
observed during the triage until he watched her type to test out the
freshly-repaired unit. As she banged away at a high rate of speed for
a full page, the tech nodded and said to her, "you and I are going to
become good friends". He was right.
(Our 32K PET shared the home office with the Selectric. One afternoon
when I was noodling around on the PET and she was deep in production
mode, during a pause in the clatter, I remarked that someday soon,
she'd be doing all of that "on one of these" (meaning a computer, not
specifically a PET). She laughed. Less than five years later, she
switched to 512K Macs and an Apple LaserWriter I).
> At work, somebody succeeded in running one at 300 baud. ?Briefly.
> That was discontinued when the "golfball" went flying into a sheetrock wall.
Wow. Who knew full-face-shields were needed in an office environment.
-ethan
So I attended Notacon, and some people may be interested to know that
there was a Lisa there brought by the CMU Computer Club. They hacked
together a demo on it, which was pretty decent given the clock speed,
etc. They claim "first lisa demo ever." --- you know how that goes
around here! :) The demo concluded with the apple logo in COLOR, which
they did by translating the brightness-level information into color on
the FPGA board.
They used an fpga development board to bring digital video signals in
off the chips, and frame buffer it and output to an HDMI output port.
They didn't actually scan convert it, but left it at its native
resolution, which was something weird. Like 700 x 300 or something?
(quick google says 720 x 364)
When pushing them for more answers on details of their hacked together
video solution, and ideas for scan converting --- they clammed up, and
said that since they will be offering a commercial product at some point
in the future, they couldn't talk about it. Weren't going to document
it publicly, post it online, etc.
I suppose it's not too surprising that college kids don't understand the
difference between raw ideas & prototyping vs executing and marketing an
actual product. I just found it disappointing that it happened at a
place where the fundamental point of getting together is to share
information. I guess they consider sharing a one-way street.
Keith
Eric writes:
>Fred Cisin wrote:
>> "trusty ST-225"??
> Well, as compared to some brands, yes. JTS comes to mind, though it
> wasn't contemporary with the ST-225.
Most of my suffering with MFM drives happened at the upper end of
the cost/complexity spectrum.
Looking back 20 years I in fact have good respect for the simpler of
the MFM drives and the ST-225 is an example.
Maybe my expectations were just lower for a drive that didn't cost
$4000 (list price of a XT-2190). But it's also quite true that ST-225's
didn't crap out at the rate as the much more expensive MFM drives
and for that I have to really give them some credit.
Tim.
Can someone here please explain to me, in ** simple English **, the
difference (in usage, not in how they work) between a "control grid
tube" and a "barrier grid tube" ... ?
I tried Googling but that led to me being more confused, not less. :)
Hi! There are bunch of S-100 Serial IO boards left so if anyone would like
one or more please let me know.
John has a nice description of the board here:
http://s100computers.com/My%20System%20Pages/Serial%20IO%20Board/Serial%20IO
%20Board.htm
These are respin PCBs which resolve all the minor issues from the original
release and the board is 100% without any modifications.
These are generic IEEE-696/S-100 serial IO boards with dual serial ports,
optional USB, and optional voice synthesizer support. There are also some
parallel pins available.
They are available for $20 each plus $3 shipping in the US and $6 elsewhere.
If you have questions you can contact me or ask on the mailing list
http://groups.google.com/group/n8vem-s100
Thanks and have a nice day!
Andrew Lynch
PS, although these are home brew PCBs you can use them in either building
your own S-100 from scratch, restoring/repairing a vintage system, just
adding them to an already working system for more IO.
MARCH is selling the following IMSAI 8080
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270739896050
Proceeds for this sale will go to the widow of a veteran Trenton
Computer Festival exhibitor whose husband died in an accident. She
donated her husband's collection to the Mid-Atlantic Retro Computing
Hobbyists, and asked that we sell one nice system from that lot to
help her financially.
Bill