test-drb March 2003

test-drb@ccmp.vtda.org

314 participants
633 discussions

by MBuhler＠itt-tech.edu

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

21 years, 10 months

More PDP-8/L repair fun (bits won't read/write)

by charlesmorris＠direcway.com

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

21 years, 10 months

Calcupen

by francois＠auradon.com

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

21 years, 10 months

Motorola MCM6665BP20 Specs

by melamy＠earthlink.net

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.

21 years, 10 months

HP 2100A hardware reference docs?

by glenslick＠hotmail.com

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 _________________________________________________________________ Help STOP SPAM with the new MSN 8 and get 2 months FREE* http://join.msn.com/?page=features/junkmail

21 years, 10 months

DEC Server 300

by cb＠mythtech.net

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>

21 years, 10 months

decserver 550 in Kansas City

by mbg＠TheWorld.com

>> 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 | +--------------------------------+-------------------------------------+

21 years, 10 months

HP 7905/9706 ??

by aek＠spies.com

>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?

21 years, 10 months

UK TV programme: The Programmers

by avickers＠solutionengineers.com

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

21 years, 10 months

Neon logic

by bnansel＠mail.nauticom.net

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

21 years, 10 months

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test-drb March 2003