RM Nimbus Logo W E L C O M E
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Nimbus PC

The Nimbus PC was a best-selling high-performance, low-cost 16-bit microcomputer from RM.

Officially launched on Monday, January 21st 1985
at the Barbican Centre London, England
During the "Hi Technology and Computers in Education Exhibition"
now known as BETT
See a photo here!

Project named the NGC - New Generation Computer

Based around the true 16-bit Intel 80186 processor. Further boosted by an optional 8087 maths co-processor.

Commonly found in UK schools towards the end of the 1980's

Nimbus; An optical phenomena (halo) caused by ice crystals in the atmosphere.

  • Intel 80186 with 8Mhz Processor
  • Fast LSI (Large Scale Integration) Graphics Controller
  • Dual bus architecture for maximum CPU memory bandwidth
  • 8051 11Mhz peripheral control
  • 8087 8Mhz maths co-processor option
  • General Instrument AY-3-8910 music chip
  • 512k Standard Memory, expandable to 1.5Mb (workstation)
  • 1.5Mb Standard Memory (server)
  • 64k Graphics RAM
  • System ROMS
  • Built-in Speaker - with volume control
  • Configuration EEPROM
  • 1 DMA Channel
  • 4 Expansion I/O Slots
  • Built-in Piconet port - Serial and Parallel interfaces
  • Positive or Negative Sync Monitor driver

       Click here for Pinouts

    1985 Launch Prices

    PC1 128K 1 x 3.5" floppy £945 £945 £1395
    PC2 128K 2 x 3.5" f1oppy £1221 £1221 £1695
    X10 128K I x 3.5" floppy
    I x 10Mb hard disk
    £2076 £2595 £2595
    TN 256K No dlsks
    Network Station
    £745 £898 £1123
    SPCN2 256K 2x3.5" floppy
    Network Server
    £2108 £2508 £2635
    XN20 256K 1 x 3.5" floppy t3152
    I x 201"1b hard dlsk
    Network Server
    £3152 £3552 £3940

    My research suggests that the retail price was never expected to be a seller and indeed artificially inflated to make the education price more appealing.
The Nimbus PC was available as a standalone or network system and could be mixed with AX and VX systems on the RM Net Z-Net based network.
Standard systems came with one or two 3.5"floppy disk drives - or with one floppy drive plus a 10/16 or 20 Mbyte internal Winchester hard disk.
RM Nimbus TN Diskless
Diskless Network stations(TN) were also available
Nimbus XW40
Further stackable external Winchester hard disk units could be added, like this XW40 40Mb unit
     Click here for the XW40

These are cartridges containing permanent copies of
programs. They fit into the slots on the front of the
   Click here for ROM Details


The Layout of the mainboard varied throughout the revisions, here is an example:

RM Nimbus PC-186 Mainboard layout

Examples of different mainboards are here:

This one is missing the 5 and 12v connectors as well as the RM Cartridge connectors

PC-186 Mainboard

This board has a 9 Pin D socket for the network, rather as onboard as above.
This board looks to have the component spaces for the network but they were not fitted.
Perhaps for cost cutting or maybe aimed at the home market.
It also includes ROM cartridge slot connectors (the blue blocks on the left)

RM Nimbus PC-186 Mainboard

This is is the 'facelift' slimline pc-186 mainboard, please see this section for more information.
Many differences here, notably the different RAM chips(bottom left), also
the different angled add-on memory card socket (bottom left) and extra power connectors (bottom middle)

RM Nimbus PC-186 slimline Mainboard

The notable difference on this board is that there is no soldered onboard memory, just empty sockets (bottom left)
No high resolution image for this one.

PC-186 MB with no memory

ROM FILE - Hard coded copyright details
Copyright Research Machines Ltd., 1983, 1984, 1985, 1986 The code in these ROMs was brought to you by:
Andy Brown (EEPROM)
Geraldine Davis (printer, floppy disk, winchester and keyboard)
Nick Goodwin (FPAC interface)
Peter Harrison (ROMpack, ZEND and general non-graphics bug fixes)
Peter Hayward (graphics input, sprites)
Peter Krall (piconet)
Duncan Machray (network design and ZEP)
Tim Pearson (graphics design, graphics output and startup screen)
Chris Tofts (graphics circles and curvy bits)
Ian Wild (who wishes to remain anonymous) (original concept,
non-graphics non-network design, startup, mummu, tick, plonk char,
sound and voice)

With additional help from:
Nick Hegenbarth (IBM character set digitisation)
The 480Z team (480Z character set digitisation)
Peter Hindshaw (startup screen design)
Dave Hornsey (upgrade from 1.25A to 1.3nX & W.W.III)

Other Examples of the original Nimbus PC are as follows:

Exploded view RM Nimbus PC-186 PC-186  3 Nimbus in a stick with a hard drive module PC-186  Research Machines PC2 PC-186 Keyboard and Monitor PC-186 RM Nimbus Single Floppy Front View PC-186 RM Nimbus X20 Custom Cards 2 PC-186 RM Nimbus X20 Rear PC-186 RM Nimbus X20 RM Nimbus PC-186 - showing the RM1404 monitor with early logo RM Nimbus PC-186 Bespoke Card RM Nimbus PC-186 Corpus Christi 2 RM Nimbus PC-186 Corpus Christi RM Nimbus PC-186 Inside View 1 RM Nimbus PC-186 Inside View 2 RM Nimbus PC-186 Inside View 3 RM Nimbus PC-186 Inside View 4 RM Nimbus PC-186 Keyboard and Mouse RM Nimbus PC-186 Running TRAINS RM Nimbus PC-186 Side View PSU Vent Slots RM Nimbus PC-186 TN Diskless Network station RM Nimbus PC-186 dual Floppy RM Nimbus PC-186 front badge RM Nimbus PC-186 showing software key slot RM Nimbus PC-186 with Dear Customer letter RM Nimbus PC-186 with Phillips CM8833-ii RM Nimbus PC-186 with manuals Monitor and disks RM Nimbus PC-186 with security key slot RM Nimbus Slimline PC-186 with RM1404A Monitors RM Nimbus pc-186 Circles and Arcs RM Nimbus pc-186 Underside View Upside down Rm Nimbus PC-186 Xebec SCSI SASI to MFM controller for RM Nimbus pc-186 pc-186-slimline-chassis-front pc-186-slimline-chassis-rear rm-nimbus-pc-186-slimline-mainboard-1 rm-nimbus-pc-186-slimline-mainboard-2 rm-nimbus-pc-186-slimline-mainboard-3 rm-nimbus-pc-186-slimline-mainboard-4 rm-nimbus-pc-186-slimline-mainboard
Information on the Nimbus PC-186
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