---
title: OHIO Scientific MODEL 500
categories:
- Computers
types:
- Home Computer
origins:
- U.S.A.
years:
- '1977'
cpus:
- '6502'
params:
  name: MODEL 500
  image: /media/museum/photos/ohio-scientific_challenger_500.jpg
  company: /companies/ohio-scientific
  company_name: OHIO Scientific
  specs:
  - label: NAME
    value: MODEL 500
  - label: MANUFACTURER
    value: OHIO Scientific
  - label: TYPE
    value: Home Computer
  - label: ORIGIN
    value: U.S.A.
  - label: YEAR
    value: '1977'
  - label: CPU
    value: '6502'
  - label: SPEED
    value: 1 MHz.
  - label: RAM
    value: 4 KB
  - label: ROM
    value: 8 KB
  - label: TEXT MODES
    value: 24 chars. x 24(?) lines
  - label: GRAPHIC MODES
    value: None
  - label: COLORS
    value: Monochrome
  - label: I/O PORTS
    value: Tape, Monitor, 1 expansion slot
  - label: PRICE
    value: 'Model 500: $298 - SuperKit: $398'
  tabs:
  - photos
  forum_thread: 65
  photos:
  - title: THE MODEL 500 SUPERKIT
    subtitle: ''
    text: 'The Superkit is a kit with several boards : an expansion board with 8 slots, the Model 500 board and a card called Model 440 Video I/O board. This card provides CRT functions and a keyboard connector.'
    image: /media/museum/photos/challenger_superkit.jpg
  - title: MODEL 500-1
    subtitle: ''
    text: ''
    image: /media/museum/photos/ohio_500_version1_1.jpg
  oc_id: 49
  source:
    url: https://web.archive.org/web/20230327103016/http://www.old-computers.com/museum/computer.asp?c=49
    date: '2023-03-27'
---

This board was used as a motherboard for the [Challenger II](/museum/ohio-scientific-challenger-ii/).

Three Model 500 versions were sold:\
**500**: The board.\
**500-1**: Fully enclosed board with power supply, reset switch and two standard terminal connectors.\
**500-8**: A 500 board in an eight slot Challenger case with power supply.

OHIO Scientific presented later an enhanced version called **SuperKit**. It was a 3 board-set with a Model 500 board without the serial interface, a video board, a 8 slot backplane board and a modified version of the BASIC ROM allowing a direct use of the video board. A TV set could be used with an optional RF aerial modulator