MARCH Fix-It, May 2013 - preliminary

Most recent revision of this page June 1 2013. It's a work in progress.


On May 18-19 2013, the MARCH club sponsored a vintage computer repair event, at their site at the Infoage museum and science center in Wall NJ. Several people brought a substantial amount of vintage computers to clean, test, repair and for use. These owners, and their tools and equipment, shared their resources and time and knowledge over the course of the weekend. Also, MARCH computing equipment was inspected and repaired by attendees and MARCH members. A similar workshop was held in 2012.

This document will describe some work and show photos of some systems during this event, which are of interest to me. It's not a comprehensive description: other Web sites will have other descriptions and photos. I'll have links to some of them. Thanks to the participants who contacted me with corrections and more information about their work.

I discuss a number of these events on my Web site, as part of my general support for computer restoration. - Herb Johnson

People on-site

who will be there? What did you work on? (please complete your name and treasures below)

- Evan Koblentz - Fearful Leader, PDP-11/20, Osborne 1
- Jeff Jonas.
- Dan Roganti - networked C64's
- David Comley - BBC Micro, HP64K analyzer
- David Gesswein.
- David Riley - DEC QBus PDP-11 with tape drive
- Matthew Whitehead - MARCH DEC PDP-11 class, VAX computers
- Bill Degnan - KIM-1, 
- Cory Smelosky
- Corey Cohen & son
- Kelly Leavitt
- Jeff Brace - Mac SE, SE/30 
- Ian Primus - DEC terminals and drives
- Herb Johnson - PDP-8/F, DEC Pro 350
- Doug Crawford - Pegasus II S-100 system, 8-inch drive work
- Vince
- Alex B.
- Jonathan Chapman - BYTE-8, various S-100
- Jeff Galinat - 8-inch floppy drives, various S-100 items
- Brian Schenkenberger - DEC Qbus stuff

To those who attended: help an old man, and please identify yourselves and your computers at the event. if attendees want a high-res version of a photo I'll be glad to send it. If you object to my coverage here, of course I'll remove the image and name. If you have more photos online or coverage of the event, I'd like a Web link; please link to me as well. I'll be glad to exchange permissions for photo use. - Herb Johnson, hjohnson at retrotechnology dot com

Computers and hardware on site - photos

can you complete the captions below?

photo 1 of event foreground: Bill Degnan contemplates his ??? as Corey Cohen's son Jeremy does whatever. background: Corey Cohen, David Gesswein, others set up their workspaces.

photo 2 of event Dan Roganti (standing) at his table of Commodores, talks to ??. Backround, Ian Primus.

photo 3 of event Jonathan sets up Byte-8 and other S-100 items as Amy works a laptop. background left: Corey Cohen preparing Sol's for keyboard repairs.

photo 4 of event Corey Cohen and son work on Processor Tech SOLs.

photo 6 of event Removed backplane and boards of Herb Johnson's DEC Professional 350. They actually stand upright that way, with the card rack removed. With card connectors cleaned, the previously-crashed Pro 350 now boots to a startup screen.

photo 8 of event Jeff Jonas? DEC terminals got a little rusty....but at least one actually RAN.

photo 9 of event A Vista brand floppy disk controller for 8-inch drives, running on an Apple II. This was used by Jeff Galinat to test floppy drives. In their time, Apple II's were often used as embedded controllers and bench-test computers.

photo 10 of event Processor Tech SOL keyboards, repairs in progress.

photo 11 of event David Comley repaired his BBC Micro, got it to the startup screen. By the end of the weekend it was looking for a boot diskette! Here's David at work. He said later in the MARCH mail list: "I worked on my BBC Micro and the club's HP64110A development station. I also worked on my Data General Nova 4/C [minicomputer] and spent some time with Evan looking at the club's Osborne 1.....I was glad to get the BBC Micro disk filing system up and running. Having neither formatted diskettes nor the utility disk to create them, I resorted to a keyed in BASIC routine which seemed to work. I was also able to get Micro-PROLOG up in ROM. My notes are here [on my Web site]. Great to see everyone and meet new folks, and I look forward to the next event. Brilliant weekend !"

photo 12 of event Left to right: Bill Degnan, Johathan, Amy. Jonathan brought a LOT of S-100, and is taking MARCH boards back home for diagnosis.

photo 14 of event Bill Degnan's COSMAC Microkit. A rare RCA brand pre-1801 development system.

photo 17 of event David Riley brought a Qbus PDP-11, running a desktop 9-track tape drive. "I had a great deal of fun, and it gave me the uninterrupted diagnosis time to nail down the root of the problems with my 9-track." Intermittant control problems appeared to be from a folded flat cable, and faulty 5-volt regulator on the drive.

photo 18 of event Jonathan patching NorthStar DOS to operate under the SOL ROM. "Just a matter of patching the console I/O calls to the SOL's ROM" he said. It was common to have NorthStar floppy controllers on SOL's, Altairs, IMSAIs as it was one of Northstar's first products.

photo BD1 of event Herb Johnson (left) attaching resistor loads to PDP-8/F power supply board, while David Gesswein (right) monitors. David's procedures to reform the caps and test the power supply board were completely successful. I describe our work on the 8/f on this linked Web page. Photo courtesy of Bill D.

photo 19 of event Doug Crawford working on a Pegasus II (a Jersey company brand) Z-80 S-100 system. "We got the system running far enough to get the boot prompt on a terminal." Several people brought and exchanged and tested 8-inch drives at the event. Doug says "Built a terminator pack for the 8inch drives, Ian tuned up my Kaypro II video drive & verified that an Amiga 500 I brought was operational."

photo 20 of event Matthew came by late Saturday and through Sunday, to work on DEC PDP-11 class computers. A number of DEC systems were brought up on his watch this weekend.

photo 21 of event Herb Johnson's PDP-8/F restored to operation! 2**12 thanks to David Gesswein for his tools, directions and efforts. I'll have more on this work.

Not photographed

Evan Koblentz worked on the MARCH PDP-11/20 (with help from others), and an Osborne 1.

Jeff Brace posted in MARCH: "Dan Roganti and I got a good start on our Multi-Player Artillery Duel project. I also was able to replace the capacitor in my SE/30 with help and parts from Ian, Jonathan and Dan."

Other Web sites about the event

Bill D.'s photos

David Comley's notes

I describe work on the PDP-8/f.

Herb Johnson
New Jersey, USA
follow this link to email me @ my email address

Copyright © 2013 Herb Johnson