Search Posts:

PDP 11/40 M7656 Serial Comms

SHARE

Return to Threads
  PDP 11/40 M7656 Serial Comms by Bill Degnan - 03/16/2015 08:17
Now that the core system is running again I can turn my attention to adding a display and disk drives to the system.

I have a M7856 10 F-C (RS232 WITH 19.2 OPTION?) i.e. serial card and few terminals including a vt52 a LA36

Instructions for booting the PDP 11/40 using RL02 drives
http://www.pdp-11.nl/peripherals/disk/rl-info.html

Next - I will replace one of the grant continuity cards and put in a M7762 (RL02 controller) in its place and attempt to boot from RL02 using M9312 ROM boot terminator card with RL02 ROM chip installed.

I had a hopefully still working RL02 (01) and I bought a second drive from Ian last year (02). I have 10 or so RL02 packs, at least one should be a RT11 boot disk.

Reply
  M7856 Setup by Bill Degnan - 03/18/2015 10:48
M7856 BERG Connector
Using guidance found in documentation and web resources I found the correct pin assignments for a serial console cable to connect from the M7856 to a serial terminal. Fortunately I had a BERG connector available. I set the jumpers to 9600 baud. Click image for larger view.


Null Modem adapter
Next I attached the EIN cable end to a null modem adapter and a longer straight-through cable. The end of the straight-through cable was attached to the COMM port of a VT 102 terminal set to 9600 baud.


PDP 11/40 with VT-102 terminal
This photo shows the PDP 11/40 with VT-102.


PDP 11 echo character program output
I toggled in a program that takes characters typed at the terminal, passes them through the PDP 11/40 and echoes them back to the terminal screen.


The progress thus far was short-lived. The system returned to an AC LO failure condition ((see thread))and the 5 amp fuse blew out. I have parts on order so I can make more permanent repairs. But at least I got a little taste of the machine. I should have waited until I finished the power supply repairs but I was impatient, can you blame me?

The RAM board was kind of flakey, I need to replace the caps on this card as well as the power supply control board's caps and resistors that have failed.

Reply
  Downloading programs via serial card by Bill Degnan - 07/18/2015 14:18
Power supply appears to be fixed after repairs and running for a few hours. We're now back to the point of being able to use a terminal to echo characters.

Next, we need to toggle in a bootstrap loader and download the absolute loader into memory. From there we can load BASIC or other programs.

Bootstraps Here
http://www.psych.usyd.ed.../pdp-11/bootstraps.html


Reply

Resources:

  • Home
  • Manufacturer photos, software, docs
  • Disk Images
  • Computer History Articles Scans and Files
  • YouTube.com Videos
  • Sale/Trade/Wanted/Miscellaneous
  • Photo Gallery
  • The Ultimate Vinage Computing Links List
  • Switch to DOS Prompt view

    • 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:

  • Vintage Computer Festival East 3.0 June 2006
  • Commodore B Series Prototypes July 2006
  • VOLSCAN - The first desktop computer with a GUI? Oct 2006
  • ROBOTS! - Will Robots Take Over? Nov 2006
  • Magnavox Mystery - a Computer, or? Jan 2007
  • The 1973 Williams Paddle Ball Arcade Computer Game Feb 2007
  • The Sperry UNIVAC 1219 Military Computer May 2007
  • VCF East 2007 - PET 30th Anniversary June/July 2007
  • The Electronic Brain August 2007
  • Community Memory and The People's Computer Company October 2007
  • Charles Babbage's Calculating Machine December 2007
  • Vintage Computing - A 1983 Perspective February 2008
  • Laptops and Portables May 2008
  • From Giant Brains to Hobby Computers - 1957 to 1977 August 2008
  • Historic Computer Magazines November 2008
  • World's Smallest Electronic Brain - Simon (1950) December 2008 - Feb 2009
  • Free Program Listings Spring 2009
  • Computer Music Summer 2009
  • Popular Electronics Jan/Feb 1975 - Altair 8800 Fall 2009
  • Early Microcomputer Mass Storage Summer 2010

    • Corp Mod G400 pic3

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