Hi guys,
It seems my 386 has gone off to join the Choir Invisible. I pulled the
motherboard to clean off some battery residue and other gunk, and
replace the RTC chip socket -- now it's completely dead. I'm getting
"D-SUB: NO INPUT" on the monitor, no beeps or noise from the board, no
signs of life whatsoever. The HDD spins up, and the lights blink, but
the brain isn't doing squat.
I did find a broken 14.31818MHz xtal which I've replaced, but still nothing.
I have a sneaking suspicion the through-plating on the RTC socket might
have gone iffy (I'll be breaking the plastic alignment bands on the
socket and soldering the top-side tomorrow) but on the off-chance this
fails to resurrect the board.. Does anyone have a 386 or 486
AT-form-factor PC motherboard kicking around?
The board I had was one of these:
http://stason.org/TULARC/pc/motherboards/I/INFORMTECH-INTERNATIONAL-INC-486…
Basically:
- Baby-AT -- fits in a mini-tower case, AT power supply
- AMD 386DX-40 CPU
- Socket for 387 or Weitek math coprocessor
- 8 sockets for 30pin SIMMs -- max 32MB, but I've been running this
one on 8MB. I've got a box of 72pin SIMMs too.
- I/O on expansion cards, or at least some way of disabling the
on-motherboard IDE controller. This thing needs to drive a Seagate ST21R
RLL controller and a WD WD1003-WA2 (not at the same time, of course!)
- A couple of 16-bit ISA slots (this board has 5, I need at least two)
I'm wishing I hadn't thrown out my old Pentium-P100 board... that would
have been just about perfect for this :(
Thanks,
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/
You don't say how much memory you're needing but I would hazard a guess that for many hobbyist or classiccmp-type projects that SRAM could be made to work with little effort.
Not that SRAM is cheapest per bit, but in terms of results per unit effort it's hard to beat. Of course it depends on what your desired result is... if you really truly want a DRAM controller, then SRAM won't satisfy you. But in terms of least effort to desired result I think SRAM is a clear winner even if you end up paying more per bit.
e.g. when in the late 90's I made a device for reading out arbitrarily formatted floppies and hard disks at MHz rates it was completely trivial to make a fast bit-buffer out of a SRAM chip and a couple of TTL counters and shift registers. Old classiccmp post: http://www.classiccmp.org/pipermail/cctalk/2000-July/151774.html
Tim.
On 01/26/11 19:00, Ethan Dicks<ethan.dicks at gmail.com> wrote:
> On Tue, Jan 25, 2011 at 9:23 PM, Michael Thompson
> <michael.99.thompson at gmail.com> wrote:
>> > I am reassembling a PDP-11/44 from parts for the Rhode Island Computer...
>> >
>> > The RA81s won't spin up, so I suspect that I need to replace the
>> > starting capacitors.
> I read through the blog - if the motors start spinning as you describe
> (I envision you mean for a few seconds; please correct me if this is
> wrong)_then_ the drive stops spinning, I doubt it's the capacitors.
> If the motors_don't_ start moving when you put the drive online, then
> that is one component to examine.
Nit pick: The online operation is the "A" and "B" buttons. The "RUN"
button is for spinning the drive up. It can be spinning and offline. :-)
> RA81s were at one point, exceedingly susceptible to HDA failure. I
> don't recall the specific ECO levels, but some version after "E" used
> a different glue than its predecessors leading to particulate
> contamination leading to catastrophic failure. ISTR looking for "H2"
> or "K2" drives after that disaster.
Yes. But I think even with the bad glue, the disk do spin up more than a
couple of seconds.
> RA81 drives have a DB25 inside. You can plug a terminal in and run
> on-board diagnostics and monitor operations. You can run with the lid
> up or lid down (snaking a ribbon cable out of the drive). The molex
> connector next to the data connector is to power a small hand-held LED
> terminal (I saw one once, used with a high voltage chassis for
> particle physics, but the terminal was the same).
Good suggestion. The terminal should be at 300 bps, if I remember right.
8N1. And data leads only is enough.
> Try plugging in a working VT220 and letting the drive tell you what it
> thinks is going on. You might find that it's starting to spin up then
> not liking what it sees and spinning down.
>
> Oh... just a detail - you mention locked heads - you_did_ pull the
> cord to retension the drive belt, right? (for safe transport, the
> RA81 has you locking the heads_and_ disengaging the motor from the
> HDA by removing belt tension). If you didn't do this step, what I
> think may happen is the onboard processor will start to spin the
> motor, sense no rotation from the HDA, then spin the motor down and
> emit a fault code. Maybe this is what you are seeing?
That was a very good suggestion. The belt can be disengaged in two ways,
depending on the version of the drive. Either a cord, or else a lever on
the inside of the outer wall.
It should be pretty obvious when you know what you are looking for, though.
With these suggestions, as well as the power control bus to check, the
drives should be possible to get running... :-)
>> > https://sites.google.com/site/ricmwarehouse/Home/equipment/dec-pdp-1144
> Reading through your blog, I don't think you will have success with
> booting 2.11BSD on your 11/44 with a TU81+ unless you have install
> media that knows about that tape controller. The 2.9BSD tapes I have
> require an "MS" device (older OSes might or might not require an "MT"
> device). Back in the day, there were several incompatible tape
> controller types, with different boot ROMs, and your install media had
> to match your controller and ROMs (or you had to toggle in the
> bootstrap). You can install 2.11BSD using vtserver and a virtual tape
> drive though. Also, if you do get real 2.11BSD install tapes, you'd
> probably want to be looking for a TU80 and, IIRC, an M7454 controller
> card.
2.11 will install fine from a TU81. The biggest problem is finding
booting roms for the TU81. TU81 is TMSCP, works the same as TK50.
Johnny
---------------Original Message:
Date: Mon, 24 Jan 2011 15:52:20 +0000
From: Philip Pemberton <classiccmp at philpem.me.uk>
Subject: CDC/MPI Wren II HH (94205-51) drive manual
To: cctalk <cctalk at classiccmp.org>
Message-ID: <4D3DA034.9000702 at philpem.me.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi guys,
<snip>
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?
---------------Reply:
I wouldn't think so since the WREN II manual in fact specifies
26LS31/26LS32s
;-)
mike
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/
I am Looking for Schematics for an IMS SIO-2 Card. I have been working
on getting my N* Horizon Running. I added the PROM Option to my N*
CPB-A2 but am having trouble with the Monitor Prom. I can't get it to
accept Keyboard Input.
I have a BYT-8 which I am now using to TEST with in order to bypass any
Problems with the Built in Serial Logic on the N* Motherboard. I have
the Manuals for the SIO but they don't have the Circuit Diagrams which I
want to look at to see the Connections from the Edge Connector to the
8251. I am hoping someone may know where I might obtain them.
TIA
Bob in Wisconsin
After another list member kindly patched VTserver.c and
recompiled, data would come out on COM2: ok but it still couldn't
"hear" the received characters.
You won't believe this... the pigtail cable inside the PC, from
the motherboard COM2 header to the back-panel DB25, had been
installed one position off (by me, of course) =:^O
The nonstandard location of TxD and ground on the DB25 should have
been my first clue, but I just ass-umed that it was something
unique to the PC and not EIA RS-232...
I couldn't see any visible damage to the COM2 ribbon cable, but
the proof of the pudding was a successful loopback test using a
jumper to connect straight to the header pins :) After carefully
examining and continuity-checking the pigtail, the inescapable
conclusion was that I must have incorrectly plugged it into the
header. Sure enough, with proper installation, data comes and goes
as ordered. And on the proper pins 2 and 3, also!
Recall that, again rather unbelievably, when I first resurrected
this old PC from the scrap heap, I found that a mouse had eaten
the mouse port cable (not joking) inside the case, but the other
ribbon cable pigtail for COM1. Probably I plugged it back in wrong
when reinstalling them both. Oh well, live and learn.
Now if I could only get TSX-Plus 6.50 to sysgen properly on SIMH,
I would have something to VTserve to my PDP-11!
-Charles
> Here's something I was thinking about the other day. I
> *know* for a fact that SCSI interface hard drives existed
> with 8" platters. I've never seen one, however. Does anyone
> know of any specific model numbers, or have any product
> information or pictures of such devices?
CDC/Imprimis/Seagate Sabre drives were 8" and available with a variety
Of interfaces. SMD, IPI-2, SCSI. J on the end is SMD, K
On the end is IPI-2, G on the end is SCSI. The part numbers
Are dizzying depending on whether's it's a CDC or Seagate number...
97201-12G is a CDC number, ST81236N is the Seagate number.
> Along the same lines, did SCSI interface devices exist with
> 14" platters? An option for the venerable Fujitsu Eagle, perhaps?
To be nitpicky Eagles are 10.5" platters in a 14" form factor.
> I know that Adaptec made a standalone SCSI-SMD bridge board. I
> have one, although I've never been able to get it to work. I
> got as far as hand-crafting SCSI commands to try to get it to
> format the drive, and it would sit there, device active, but
> the drive never stepped or seeked off the first cylinder.
I have seen Eagles with bridge cards in the back. I don't think
Fujitsu made them that way but they were added by US-based vendors.
You are most likely to find Sabre and SCSI-SMD bridge drives if you find
Late 80's/early 90's Sun installations. If you're lucky you can find
Some SCSI-Pertec Formatted bridges and tape drives too.
Tim.
Evan writes:
> BUT .... wouldn't everyone also agree that, at the very
> least, to be a "computer" a machine must be programmable?
Personally, I would not agree.
In the 1940's "computing" definitely meant solving systems
of linear equations (ABC) and artillery tables (ENIAC) and
other applications (e.g. Analytical Engine).
Note that even today LAPACK (linear equations) is the
Standard supercomputer benchmark.
In the 2000's "computing" usually means E-mail, Web, and
Word Processing, all of which can be done on machines
that lack or lock out end-user programming.
And compare with 21st century "quantum computing" which is set
up on optical benches.
Tim.
