website/content/museum/rair-microcomputer-business-computer.md

---
title: RAIR microcomputer Business Computer
categories:
- Computers
types:
- Professional Computer
origins:
- U.S.A.
years:
- '1983'
cpus:
- 16-bit Intel 8088 &amp
params:
  name: Business Computer
  image: /media/museum/photos/rair_business-computer_1s.jpg
  company: /companies/rair-microcomputer
  company_name: RAIR microcomputer
  specs:
  - label: NAME
    value: Business Computer
  - label: MANUFACTURER
    value: RAIR microcomputer
  - label: TYPE
    value: Professional Computer
  - label: ORIGIN
    value: U.S.A.
  - label: YEAR
    value: ? 1983
  - label: END OF PRODUCTION
    value: Unknown
  - label: KEYBOARD
    value: Full stroke keyboard, 83 keys, 10 programmable function keys, numeric keypad
  - label: CPU
    value: 16-bit Intel 8088 & 8-bit Intel 8085
  - label: RAM
    value: 256 KB (1 MB max.)
  - label: TEXT MODES
    value: 80 x 25 characters
  - label: GRAPHIC MODES
    value: high resolution ?
  - label: COLORS
    value: '8'
  - label: SOUND
    value: Unknown
  - label: SIZE / WEIGHT
    value: Unknown
  - label: I/O PORTS
    value: 4 x terminal connectors (RS 422 compatible), 2 x RS232 ports
  - label: BUILT IN MEDIA
    value: 19 MB Winchester hard-disk + 1 MB 5.25'' floppy disk drive
  - label: OS
    value: CP/M, M/PM, PC-DOS
  - label: POWER SUPPLY
    value: Built-in power supply
  - label: PERIPHERALS
    value: up to 4 additional hard-disks, magnetic tape drive, bidirectional printer (160 c/s)
  - label: PRICE
    value: Unknown
  tabs:
  - photos
  - adverts
  photos:
  - title: BUSINESS COMPUTER
    subtitle: ''
    text: ''
    image: /media/museum/photos/rair_business-computer_1.jpg
  adverts:
  - title: FRENCH AD (DEC. 1983)
    subtitle: ''
    text: '"Sorry, you don''t play with me"'
    image: /media/museum/pubs/rair_business-computer_pub_1.jpg
  - title: UK ADVERT (JULY 1984)
    subtitle: ''
    text: ''
    image: /media/museum/pubs/rair-business-computer_uk-pub_july-1984.jpg
  comments:
  - author: Guenter H Krauss (Germany)
    date: Thursday 7th April 2011
    text: Well, well, this is so 1980ties, the good old days when everything sold. The RAIR BC was a great idea which competed with color-screen but no graphic against the early PC graphic. The Display was just a line-display terminal. It was pretty slow but sold well in Germany, but nowhere else. Especially it was OEMed to Pitney Bowes who sold the machines under their own name. I believe over 2000 units were sold during a few years. This was a big number then. The machines died quickly from power supply problems and heat. I remember we even ran them in heat room for 72 hours to ensure that the machine survives.
  - author: David Evershed (UK)
    date: Monday 17th February 2020
    text: |-
      At Rothmans cigarette company we sought to use RAIR computers to distribute our computer systems from a central mainframe to local operations in factories, warehouses and offices around the UK.

      We took delivery of the first off the production line around 1981 and had only a few models for software development at first.

      We found that the machines were not powerful enough to do the jobs we had planned for them and had to change from distributed micro computers from RAIR\
      to distributed midi computers from ICL and later IBM.
  - author: Pragnesh L Patel (San Jose, California USA)
    date: Wednesday 9th May 2018
    text: |-
      It was great time working with RAIR and DTI. In 81. Trough 98\
      At London, Germany and USA Bay are\
      Regards to all\
      From\
      Manisha and Pragnesh Patel
  - author: Bharat Ghayal (United States)
    date: Tuesday 10th November 2015
    text: I used to service these very early PC''s. Had great fun doing so with a fantastic and dynamic management team. We all lived a good life out of it. The PC''s were multi-tasking units that supported dumb terminals. CPM and MPM were the OS''s supported. Mark Potts was the main driver for great venture and he also opened offices in SF (USA), Germany, France. Enjoyed training Guenter''s technician''s. It was way ahead of its time. Long live "The Black Box".
  oc_id: 1194
  source:
    url: https://web.archive.org/web/20230608162506/http://www.old-computers.com/museum/computer.asp?c=1194
    date: '2023-06-08'
---

The RAIR Business Computer is an obscure system since nearly nothing can be found on the net about it (apart from here :-))

The Business Computer is a multipost system. It can control/serve up to 4 attached terminal stations via RS422 connectors.

Its main particularity is to mix two technologies: 8-bit with its Intel 8085 CPU and 16-bit with its Intel 8088 CPU. Thus it can run CP/M, MP/M and PC-DOS software with no problem (according to the advert).

For mass storage, the system is equiped with a 19 MB Winchester hard-disk (up to 4 can be mounted) and a 5.25'' 1 MB floppy drive.

---

Lots of interesting information from **Tim Hill**\
I managed the design of this system and was responsible for most of the OS software. Hardware design was by Dick Akers and Bob Marsh (of Processor Technology fame). Industrial design was by Mike Nutall (now in ID3) and for the time was pretty "wow" (most of the competition was sheet metal). The main unit was based on a RAIR Black Box but included two new features: a dual-CPU processor card (8085 and 8088) and a console card capable of driving four "consoles".

The dual-cpu card could only run one processor at a time; they switched back-and-forth under a software controlled dance. The 8088 was the main CPU, with the 8085 kicked in to run legacy 8-bit software (of which there was a lot at that time). Later units replaced this board with an early 80286 cpu card and running 8-bit software was handled by an emulator (written by me) -- not as crazy as it sounds as in fact it was \*faster\* than the hardware 8085! The display card was probably the most interesting part. The single card contained a dedicated 8085 cpu with enough muscle (for then!) to drive 4 color displays and handle keyboard input. This allowed the system to run 4 console sessions at once, even though each "console" was actually just a CRT and dumb keyboard.

The OS was MP/M-86, which could run the 4 consoles simultaneously. Native 16-bit CP/M programs ran directly. To run an 8-bit program, a tool called RUN85 was used which created a virtual 8-bit CP/M environment (easy since the two OSes were very similar) and then handed off to the 8-bit CPU for a time-slice. In addition, a purely software based MSDOS emulation facility allowed the "new" programs written for MSDOS to run as well; all of these at the same time just by running an application. Quite advanced for its time.

The achilles heel of the system was the slow performance of the display card (the 8085 really had trouble keeping up with the main system) and the lack of software that could support the (for the time) spiffy color display output. Overall, though, the system was well engineered and in some ways way ahead of its time.

<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>