Search Posts:

Intersil 6100 PDP 8 Homebrew System

SHARE

Return to Threads

  Intersil 6100 PDP 8 Homebrew System by Bill Degnan - 03/28/2013 23:40
Took a few photos of a homebrew Intersil 6100 PDP 8 Homebrew computer built by William F. Dudley Jr. which he donated to MARCH.


More photos

I did not get a chance to photograph the ROM card (need to download the 2708 ROMs) nor the processor card. The front panel is a primitive four-digit octal dial. Here is a thread from Mid-Atlantic Retro message board:

William F. Dudley Jr. donated another wonderful box of homebrew parts to MARCH: a new unused Intersil 6100 eval kit, several PHI-deck digital cassettes (2 in the original blue eval cases), spare memory cards and schematics.
The intention was to build a PDP8
using the 6100 chips and the PHI decks
emulating DECtapes to run OS8 and all the PDP8 software.
Each memory card is 4k of 12 bit DRAM,
8 max per system.

They're all spare parts for the PDP8 he built.
That's the "mystery machine" from a few weeks ago,
so MARCH now has a homebrew PDP8!

Bill Dudley identified the "mystery machine" as his.
The flip-chip backplane was a clue
that it is DEC compatible!

> That's it. PDP-8 using the 6100 chip set.
>
> Oh, and the LEDs are actually HP dot matrix LEDs
> with builtin counter/decoder/driver/LED.
> Quite high-tech for 1976.
>
> If it's got that "flip-chip" bus, a baby blue front panel,
> thumb wheels, and those same memory cards, then that's it.

Later he added more info:
We'd need the following:
(to power system) 5v, +/-12v
serial terminal (ADM3A, TTY, etc)

and then, if it "works", you'd get a simple "ROM monitor" program that allows you to examine memory etc.

We implemented "extended memory" for our PDP-8, i.e. the ability to have up to 8 banks of 4K RAM. If you look at the actual hardware, you'll find three complete memory boards and one partially stuffed. That one is bank 7, which I *think* might have a monitor ROM burned into it.

> There are two 2708's on a card in the system. I was thinking it was a
> current loop set up, I can set the PC to the ROM address that I think
> is written on the chips, attach to a terminal (rs232 or current loop)
> and see what happens...come to the workshop if you want to do this with me.

It's not current loop, I built it to do RS232. That thumbwheel switch on the end of the ribbon cable is the baud rate selector: 110,150,300...9600 are the probable values.

Likely the reset button will cause execution to begin in the monitor.



Reply

Resources:


Buy a Commodore Computer Poster

Popular Topics and FAQs


  • Commodore B Series Tips and Tricks
  • Aerocomp TRS 80 M 1 Expansion Unit DDC
  • Items Wanted
  • Lobo Max 80
  • Zenith Z-19-CN
  • Prototype PET 2001 photo
  • Using Toggle Switches to Analyze Memory
  • Commodore Disk Archive Project
  • PET 2001 Prototype at Gametronics 1977
  • Jim Butterfield Photo
  • IMSAI 8080 With Processor Tech. Cutter
  • Secrecy is the keystone of all tyranny
  • Cromemco System Three
  • Northstar Horizon - Boot Problem
  • Computer History and Restoration Links
  • Commodore BX-256-80 - 8088 Co-processor
  • S-100 board testing with Z-80 ICE
  • Donner 3500 - an early portable computer
  • Digital (DEC) PDP 11/05 NC Assembly
  • Univac 1219 rescue
  • IMSAI 1.4 BASIC vs. MITS 8K BASIC
  • Fido BBS listing node list 6-13-1986
  • PDP 8e
  • MITS 88-2 SIO (2SIO) for BASIC
  • Visual Technology Inc Model 1050
  • Amiga 2500 Restoration
  • The Evolution Of IBM Computers
  • Replacement teletype print hammer head
  • Archiving and Copying Software 101
  • Computers Built 1940 - 1950
  • CBM B-520 (a.k.a B256-80 or B500 256)
  • RCA COSMAC Microkit
  • Commodore 64K C-116 Mods
  • MITS 8800b Turnmon 9600 baud
  • Catweasel, 8in and 5 1/4
  • Raspberry Pi as Gateway to Internet
  • Digital PDP11 late 1969 early 1970
  • PDP 11/40 72 inch cabinet model
  • PDP 11/40 Industrial 11 model
  • Digitial MicroVAX 3100 30 System
  • Digital VAX 4000-200
  • Commodore 64 / 1541 DRIVEKNOCK
  • Booting the System Using RL02 drive
  • PACS: Reflections by Kathleen Mauchly
  • Tele-Graphic Computer Systems Inc.
  • Commodore B Series SID Jukebox?
  • Installing Core into PDP 11/40
  • Setting Up OpenVMS 7.1 DNS CLERK
  • Felt-Tarrant Comptometer Model J
  • NextStation Color
  • Digital Rainbow (PC100-B2)
  • 1970 Compusad Compulogical Tutor
  • Archiving Papertapes Using DSI NC 2400
  • 1976 P.C.C. Features the MAI JOLT 6502
  • 1961 Beckman DEXTIR Computer
  • UNIVAC 1 and UNIVAC File Computer 1
  • Past Issues:


    writer screen

    This image was selected at random from the archive. Click image for more photos and files from this set.