test-drb July 2016

test-drb@ccmp.vtda.org

190 participants
243 discussions

by mattislind＠gmail.com

So after replacing a microcode PROM on the PDP-11/05 control board and then concluding that the remaining problem relating to indexed addressing was caused by one single micro code line that got missing when typed in, desoldering the PROM, program two more bits (0xf to 0x5), the CPU is now working. Passing the D0OA diagnostics and the D0NB (except for the mov r0, (r0)+ tests) But during the journey the core memory died. I am used to things failing in my face. The M9301 board started of working. Then it developed some kind of amnesia, permanently forgetting what was once stored. When this was cured with yet another PROM, one, then a second DEC8881 driver on the M9301-YF gave up. But now it seems to work. So finally I am back to the core memory. Luckily I had a spare set so I could find at least what board that was failing. Card swapping gave that the G231 module was at fault. The failure mode is that it does read out the contents once. The second time it reads out all zeros. Write never works. Apparently it is the write / write back mechanism that is failing completely in the G231 module. Since it is in fact reading, the X / Y selection seems to work and most of the writing takes place on the G110 as far as I understand since it contains the Inhibit drivers. So what part of the G231 is specific for the write? I have a few other G110 / G231 modules with different types of failure modes so it would be really nice if someone with MM11-L know-how would step forward and share all the details on this board set. I will continue to browse the schematic and the user manual to try to find the failing component, but help is highly appreciated! /Mattis

8 years, 1 month

Nova 3 front panel

by henk.gooijen＠hotmail.com

Van: jim stephens

8 years, 1 month

heap of floppy disks

by lyokoboy0＠gmail.com

I picked up two crates jam packed full of floppys today. Bunch of random old utilities in there, borland turbo asm, turbo pascal, windows for workgroups etc. I found a set of disks with the DEC digital logo on them. 4-5 disks, says dos for the dec pc. Some utilitys too. Are these of any use to anyone, or is it just a stock dos install with a dec sticker on the disk? There are little heaps of disks on just about every surface around here, i will post back with a complete list of what is here to see if anyone is interested in what is here. I just want some of the software off of the disks, i don't necessarily want to keep the two full crates of disks around . There is also an original copy of doom on floppy that looks to be complete. --Devin

8 years, 1 month

Multiflow Trace 14/300 close to being scrapped in Texas

by evan.linwood＠eastek.com.au

Hi Mark, it wasn't myself either. Apologies (and to Brian, James and Jon) I was watching & wanting to respond but got hit by a wall of things, then noticed that someone had bid on it. Very glad to see it was acquired, and that Chris could confirm.

8 years, 1 month

Nova 3 front panel

by henk.gooijen＠hotmail.com

Van: jim stephens

8 years, 1 month

Compucorop 122E - Manual

by draeger5＠hotmail.com

Hello, just came across this site. I recently got a Compucorp 122E, but without any manual. I would like to use this calculator for tests in programming - does anyone have a manual/pdf? Thanks, Matthias ps.: this mail is for the "list" - how can I have access to the list? How do I see a reply, in case there is one? Tel.0049-6741-1720 http://m-draeger.com/ Matthias Draeger Auf dem Haehnchen 32 56329 St. Goar/ Germany

8 years, 1 month

Possibly rarest Apple 1 ever for auction

by jnc＠mercury.lcs.mit.edu

> From: Corey Cohen > It was not someone at the PCB manufacturer. They would not have had > access to the prom software. So, do you have a theory about where this came from? (There is absolutely zero snark here, this is a serious question. It's quite a puzzle, and an interesting one.) Maybe a collaboration between two people, one at Apple, one at the PCB house? 'Make two extra boards, and I'll trade you the PROMs for one of them.' Can't do it with just a person at the PCB house - as you point out, need the ROMs. But you'd think that if someone at Apple just pulled a board, that would be noticed (board count wrong). Noel

8 years, 1 month

VT420 schematics

by lars＠nocrew.org

Hello, Does anyone have schematics for the DEC VT420 terminal? Thank you, Lars Brinkhoff

8 years, 1 month

HP Computer Museum in the (local) News

by rdbrown0au＠gmail.com

http://www.abc.net.au/news/2016-07-22/vintage-computer-museum-revives-hp211… A keen mountaineer who died trekking in Tibet has left a rare computer collection behind as his legacy. Surrounded by bushland in the eastern suburbs of Melbourne is a wooden shed with barn doors. It closely resembles a shed in California where, in 1939, Bill Hewlett and Dave Packard launched the company that would become HP. The much larger Australian shed is home to the HP Computer Museum, filled with ageing computers, printers and calculators, most of which are a dull light grey. ...

8 years, 1 month

Possibly rarest Apple 1 ever for auction

by cctalk＠snarc.net

Possibly the rarest Apple 1 ever is up for auction. The seller is working through CharityBuzz, which will display the computer at VCF West next month. CB's auction site: http://apple1.charitybuzz.com/ MacRumors covered it: http://www.macrumors.com/2016/07/21/charitybuzz-auctioning-unique-celebrati…

8 years, 1 month

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test-drb July 2016