Hi Tom,
I found you after a google search.
I used to have several working H89s but I got rid of all them. Now I've
found 5 H89 floppies which I think contain good information but of course I
can't read them any longer. I live in Grand Rapids Michigan and would drive
a couple of hours to visit someone who owns a working H89 just to find out
what is on those floppies. Do you know of anyone who could help me?
Max Buhler: mbuhler(a)itt-tech.edu
Some of my bits not setting turned out to be bad parts on the
front panel! 15 years ago I installed LEDs/resistors in place of
all the (mostly burned out) incandescent lamps. One had a cracked
composition resistor, and the other an open (base-emitter) driver
transistor.
As I posted earlier, the problem with the core not reading/writing
bits 5-11 was indeed the MEM ENABLE signal from the M617 in slot
A09. But the 7440 was good for a change (not one of the bad batch
with 7005 date code). Turns out the wire from that pin on the
backplane was installed too tightly at the factory and had shorted
through the insulation to a ground pin. Now the core works, and
CPU executes various test programs; SR, AC, MB, MA all working
fine... EXCEPT it won't read/write on any of the 128 bytes of page
0! Going to try to figure that one out tonight...
Another strange find - the PROTECT key did not, in fact, protect
the upper page (7600-7777) of core. I found a factory-appearing
wire on the backplane, jumpering the output of an inverter
directly to ground! Some idiot probably was bothered by noise
giving false PROT errors or couldn't figure out that the switch is
off when in the down position, and just shorted the signal out.
Now that works, too. Didn't fix the page-0 problem either.
The DF and IF switches do nothing (i.e. flipping them does not
bomb a running program, or prevent reading/writing from the front
panel switches), but I think that's normal without the extra 4K
installed.
-Charles
Hi all,
How would one go about disassembling a calcupen? Mine is not coming up
anymore with a fresh battery. I would like to see what's up inside: look for
corosion and stuff.
Thanks
Francois
Minnesota
Hi Tim, The format is 64K x 1 with an access time of 200ns. It
was introduced sometime before 1982 as it appears in my 1982
IC Master. I have specs for the 6664 part if that would help,
but it is supposed to be compatible with the more generic 4164
chip in case you already have specs for that.
Best regards, Steve Thatcher
>--- Original Message ---
>From: "Tim" <thodgson(a)pnc.com.au>
>To: <cctalk(a)classiccmp.org>
>Date: 2/28/03 2:02:18 PM
>
G'day,
>I've recently been going through a few items I had tucked away
& found a bunch
>of IC's...
>Now I'm going through them, one by one, & trying to find as
much info I can
>find.
>
>So far, I've found nothing on the Motorola MCM6665BP20, a 16pin
chip with a
>secondary code of FQD8432.
>I'm trying to find complete specs, any idea's?
>
>Thanks in advance,
>
>Tim.
I picked up an HP 2100A a couple of days ago and before I do anything with
it I'd like to find some hardware reference docs which describe the boards
which should be installed, along with schematics and such. I haven't found
a copy on the web. Does anyone know where a copy might be found?
I have no idea if I have a full set of cards for a functional CPU. All of
the blue slots are full of A1-A9 cards. I assume those are the main CPU
logic cards. It also looks like there is a 4K two card core memory set
(XYD/SSA) plus an 8K two card core memory set. Plus whatever the ID/IDL/DC
cards do.
The power switch key is gone. Is there a way to bypass that? Also the F5
fuse cap and fuse is gone from the back panel. I hope that is not a sign of
power supply problems.
The boards installed in the CPU card cages are the following:
Front Cage Rear Cage
A1 XYD -\ 02100-60052 top jumper
A2 SSA(4K) -/
A3 SSA -\ 02100-60054 top jumper
A4 XYD -/
A5 ID(16K) -\ \ ribbon cable top jumpers
A6 IDL | /
A7 DC -/
A8
A9
(twelve empty slots)
TERM
BUF'R'D TTY 12531
_________________________________________________________________
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What does a DEC Server 300 look like? About how big are we talking about?
I unloaded the dumpster pulls from last night, and one of the manuals was
marked DEC Server 300. So I'm kind of assuming that might be the DEC the
other parts came from. I'm thinking of going back for another dive
tonight, so I'm wondering what exactly I should be looking for. Or if
this is a large machine, I can pretty well say that it isn't in the
dumpster.
-chris
<http://www.mythtech.net>
>> I read somewhere that it could be converted to a 11/53 with a minimal
>> effort. How much trouble?
>Rip out the CXA's (16-port serial boards), add a disk and/or tape
>controller, and perhaps some memory. Off you go. The heart of
>the DECserver 550 was/is indeed a barebones /53 CPU. Which comes
>with 512KB RAM on the CPU card, and its console serial port.
I don't believe you are "ready to go" after this mod. I seem
to remember that the ROMs on the DS500 use special boot code
and that they need to be replaced to be a normal 11/53. I
saw some posts on one of the newsgroups from someone who had
done it.
Megan Gentry
Former RT-11 Developer
+--------------------------------+-------------------------------------+
| Megan Gentry, EMT/B, PP-ASEL | email: mbg at world.std.com |
| | |
| "this space | (s/ at /@/) |
| unavoidably left blank" | URL: http://world.std.com/~mbg/ |
| | "pdp-11 programmer - some assembler |
| (DEC '77-'98) | required." - mbg KB1FCA |
+--------------------------------+-------------------------------------+
>Any body on here seriously interested in the HP 7905 and 7906 disk drives?
possibly, depending on location (i'm in the SF bay area)
12995 isn't showing up on any of my parts lists. Was it an HP1000 interface card?
There's a programme on BBC2, Thursday 6th March at 6.30AM (yup, AM), called
"The Programmers"
It purports to be about "the history of computing, from hardware and
software to programming, and the people who devised the code to make them
work".
I'll tape it (if I remember). I suspect it's an Open University programme,
so with a bit of luck it'll show some truly old hardware, as well as some
shocking kipper ties and psychedelic chunky-knit jumpers :)
--
Cheers, Ade.
Be where it's at, B-Racing!
http://b-racing.com
I came across reference to a file, LAMP.ZIP, you posted briefly for the
Classic Computer list back in '99. Would it be possible for me to get this
file? I'm fascinated by the idea of making counters, logic gates, and
memory elements using neon lamps, but repeated google searches reveal very,
very little hard information (other than there were such circuits).
Also, I've read a few pages on early calculators (such as the Anita) using
something similar to neon lamps for logic gates and ring counters, though
the pictures lead me to believe they are actually 4-lead gas triodes or
thyratrons of some kind. Do you know what these beaties actually were?
Finally, I've repeatedly run across mention that neon device switching is
slow, but how slow are they?
You assistance is appreciated!
-RLN
