---
title: OSM Computer Corporation Zeus 4
categories:
- Computers
types:
- Professional Computer
origins:
- U.S.A.
years:
- '1982'
cpus:
- Zilog Z80A
params:
  name: Zeus 4
  image: /media/museum/photos/osm_zeus4_1s.jpg
  company: /companies/osm-computer-corporation
  company_name: OSM Computer Corporation
  specs:
  - label: NAME
    value: Zeus 4
  - label: MANUFACTURER
    value: OSM Computer Corporation
  - label: TYPE
    value: Professional Computer
  - label: ORIGIN
    value: U.S.A.
  - label: YEAR
    value: december 1982
  - label: CPU
    value: Zilog Z80A
  - label: SPEED
    value: 4 MHz
  - label: RAM
    value: 64 Kb + 64 Kb x number of users (up to 8) = 576 Kb max.
  - label: TEXT MODES
    value: 80 x 25 CP/M standard
  - label: GRAPHIC MODES
    value: none
  - label: COLORS
    value: monochrome through terminal display
  - label: SOUND
    value: None
  - label: SIZE / WEIGHT
    value: 8x13x15 inches / 24,6 lbs
  - label: I/O PORTS
    value: 4 x serial ports (2 users, 2 master), 2 x parallel ports,
  - label: BUILT IN MEDIA
    value: Hard disk (from 6 to 25 Mb) + 5.25'' floppy disk drive (standard 250 Kb or IBM 1 Mb)
  - label: OS
    value: CP/M, M/PM, MUSE or ZMOS
  - label: POWER SUPPLY
    value: Built-in PSU
  - label: PRICE
    value: 'USA (1983) : $5,595 (2 users systems) / $1000 (2 users increment) / $8,595 (8 users configuration)'
  tabs:
  - photos
  - adverts
  forum_thread: 1300
  photos:
  - title: ZEUS 4
    subtitle: ''
    text: ''
    image: null
  - title: ZEUS 4 IN ACTION
    subtitle: ''
    text: ''
    image: null
  adverts:
  - title: US ADVERT (1983)
    subtitle: ''
    text: ''
    image: /media/museum/pubs/osm_zeus-4_pub-1983.jpg
  - title: US ADVERT (DEC. 1983)
    subtitle: ''
    text: ''
    image: /media/museum/pubs/osm_zeus-4_pub-dec-1983.jpg
  - title: ZEUS FAMILY SPECIFICATIONS
    subtitle: ''
    text: dated 1983
    image: null
  oc_id: 1335
  source:
    url: https://web.archive.org/web/20230415212108/http://www.old-computers.com/museum/computer.asp?c=1335
    date: '2023-04-15'
---

OSM Computer Corporation, based in Santa Clara California, produced several multi-user CP/M computers called Zeus.

The Zeus 4 was released in 1982, and is a natural follow-up of previous systems: [Zeus](/museum/osm-computer-corporation-zeus/), Zeus II, Zeus 3 and [Zeus 3x](/museum/osm-computer-corporation-zeus-3x/).

The OSM Zeus 4 is a Z80 based multi-user computer that supports a single hard drive (from 6 to 25 Mb) and up to 8 users (4 on first models) via dumb terminals plugged into RS232 ports. The ports supports several terminal emulations as well as serial printers and modems.

The Zeus 4 supports the 3270 data communication protocol, which permits the system to exchange information with IBM or IBM-compatible host mainframes.

There are three electronic boards inside the computer. One is the disks controller, the middle one is the master CPU and the last one is the slave CPU board. On the slave board there are 2, 4 or 8 entire Z80 based computers. There are all "Networked" to the master board through a ribbon cable on the side.

The Zeus computer uses MUSE (Multi User System Executive) as its operating system, a CP/M compatible OS for multi-user computers from OSM. It incorporates all the standard features of CP/M, while adding file management capabilities such as multi-user file sharing, password protection, print spooling, data security and auto-searching. Later, the ZMOS operating system, another multi-user CP/M compatible OS, was also available.

When OSM went out of business another company purchased their stock and manufactured a new version called the Zeus 4x that supported 16 users.

<table> <tr> <td></td> <td>We need more info about this computer ! If you designed, used, or have more info about this system, please send us pictures or anything you might find useful.</td> <td></td> </tr> </table>