website/content/museum/litton-monroe-oc-8880.md

---
title: Litton - Monroe OC-8880
categories:
- Computers
types:
- Professional Computer
origins:
- Japan
years:
- '1981'
cpus:
- Z80
params:
  name: OC-8880
  company: /companies/litton-monroe
  company_name: Litton - Monroe
  specs:
  - label: NAME
    value: OC-8880
  - label: MANUFACTURER
    value: Litton - Monroe
  - label: TYPE
    value: Professional Computer
  - label: ORIGIN
    value: Japan
  - label: YEAR
    value: '1981'
  - label: BUILT IN LANGUAGE
    value: Unknown
  - label: KEYBOARD
    value: Full stroke keyboard with function keys and numeric keypad. 93 keys.
  - label: CPU
    value: Z80
  - label: SPEED
    value: Unknown
  - label: CO-PROCESSOR
    value: Unknown
  - label: RAM
    value: 16 KB (128 KB max)
  - label: ROM
    value: Unknown
  - label: TEXT MODES
    value: Unknown
  - label: GRAPHIC MODES
    value: Unknown
  - label: COLORS
    value: Unknown
  - label: SOUND
    value: Unknown
  - label: SIZE / WEIGHT
    value: Unknown
  - label: I/O PORTS
    value: External disk drive, expansion bus, composite video output (monochrome), AUX serial I/O, COMM I/O, parallel printer interface
  - label: BUILT IN MEDIA
    value: One 5.25'' disk drive (300 KB)
  - label: OS
    value: CP/M
  - label: POWER SUPPLY
    value: PSU built-in
  - label: PERIPHERALS
    value: Unknown
  - label: PRICE
    value: Unknown
  tabs:
  - photos
  - links
  photos:
  - title: OC 8880
    subtitle: ''
    text: Thanks to [Jan Soderberg](http://w1.184.telia.com/~u18407217/) for this picture.
    image: null
  - title: SIDE
    subtitle: ''
    text: |-
      Notice the on/off switch on the side of the case.

      Thanks to [Jan Soderberg](http://w1.184.telia.com/~u18407217/) for this picture.
    image: null
  - title: REAR
    subtitle: ''
    text: Thanks to [Jan Soderberg](http://w1.184.telia.com/~u18407217/) for this picture.
    image: null
  links:
  - title: Jan Söderberg Monroe's page
    url: http://w1.184.telia.com/~u18407217/monroe/monroe.html
    text: Some pictures and a nice description
  - title: Litton-Monroe history
    url: http://www.datamath.org/Featured_Companies.htm
    text: You will find here a small Litton-Monroe's history
  comments:
  - author: Knut Roll-Lund (Norway)
    date: Saturday 6th June 2020
    text: |-
      Hi again all. The teledisk images have 16 sectors per track this makes them 360K. This makes them DD (Double Density) which is why I could write them on a PC with a 1.2MB drive.\
      The Micropolis 1015-5 in The OC-8880 is a QD 400K it seems to spin at 300 RPM but should have 20 sectors per track and 80 tracks. I thought 5,25" QD would rotate at 360 RPM similar to 8" so clock would be double of DD. I don''t know if it has two speeds and actually boots at DD and 300 RPM but can also do 360 RPM and QD.\
      I wonder if QD would be similar to HD and use a significantly higher current to write (bias) like PC 1.2MB does.\
      I will proceed to look at the floppies on another computer to see if there is anything sensible there. Also check frequencies on FDC and CPU to see if that makes sense.\
      The drive seems OK, though rotating speed may be a little off, if other things are OK I will try to adjust that.
  - author: Knut Roll-Lund (Norway)
    date: Thursday 28th May 2020
    text: |-
      I tried the TeleDisk images Alejandro Daniel Perez found. Unfortunately no success yet.

      I created real media with ms-dos on a 1.2MB 5.25" drive (has 80 track) and used DD 360K media, though it is not certified for 80 track. This seemed to go well, so far so good.

      The OC-8880 did respond with some more messages so it was trying. Loading, but didn''t like the floppy. From the sounds the drive may be bad.

      I will try to find out if the floppies are ok on a different old computer. I will try to find out if the drive is bad, if it is an 80 track drive etc. In 1981/1982 80 track wasn''t that common. Two years later it was pretty common.

      BTW I will try mesuring what frequency the CPU has, and confirm if signals match Z80.
  - author: Alejandro Daniel Perez (Argentina)
    date: Thursday 16th April 2020
    text: |-
      Hi everyone! I believe that I have found a disk image to check with this computer here: http://www.retroarchive.org/maslin/disks/misc/index.html

      The image name is monroe.td0 and monroe88.tdo, if anyone can check it I would like to know if the images are working fine. I have a Monroe OC-8820 but it still under repair
  - author: Nils H (Sweden)
    date: Friday 16th August 2019
    text: |-
      The Monroe OC8800 could probably run CP/M, but it was offered with another operating system called OS8MT which was a multi-tasking 8-bit operating system.

      There was a Basic interpreter that is related to the Luxor ABC800 series computers and the Diab Basic on the Motorola Unix computers.

      There''s even an MS-DOS version of that Basic named basic2pc. There are however some differences in instruction set, but those differences are minor. Search for BASIC2PC.ZIP to find it. The basic is a semi-compiling basic which makes it fairly fast when executing.

      One Monroe-specific instruction that I happen to remember is "OPTION EUROPE", which allowed you to programmatically determine if there should be a comma or dot as decimal separator.
  - author: Knut (Norway)
    date: Sunday 1st November 2015
    text: Stefano''s link is now broken. I had to move my site, so the link should be http://knut.one/LittonMonroeOC8880.htm and yes the 2KB EPROM is correctly a dump of the boot ROM of the OC8800 but it contains only initialization and ability to load and execute a bootsector from a floppy. Not very useful if you don''t have a bootable floppy for this computer (probably CP/m). I have the machine but no floppy...
  - author: Stefano
    date: Tuesday 29th July 2014
    text: |-
      http://home.online.no/\~kr-lund/LittonMonroeOC8880.htm

      The MESS project claims they need its ROM dump.\
      Pehaps the 2kb image in this link is useful ?
  - author: Bob Hall (usa)
    date: Thursday 10th November 2011
    text: The OC8800 and 8820 were manufactured in Monroe''s plant in Lexington South Carolina. This was the first of two attempts of Monroe to enter the desktop computer business. Operating memory was either 256k or 512K. dual 6" floppies and optional 5 or 10 Megabyte external hard drives. The model shown was intended as a system dedicated to educational use. This incorporated early verisions of software to allow a student to draw and color objects. The acutal commerical version was a single cabinet design with a 80 column dot matrix printer using 4" calculator rolls the display was an orange monochrome 8" monitor.
  - author: PeriSoft (New York, USA)
    date: Saturday 24th February 2007
    text: Gotta love the lace doily under the monitor. Classic!
  oc_id: 569
  source:
    url: https://web.archive.org/web/20221128054726/http://www.old-computers.com/museum/computer.asp?c=569
    date: '2022-11-28'
---

Info needed about this obscure CP/M computer!

Monroe - a subsidary of Litton Inc. - used to produce and sell calculators for years from 1912.

Very little is known about this CP/M system. To use the floppies you had to type in OPEN FPY0:

---

Thanks to Jan Söderberg for the pictures.