ICL DRS Professional Workstation

The ICL DRS was a range of departmental computers from International Computers Limited (ICL). Standing originally for Distributed Resource System, the full name was later dropped in favour of the abbreviation.

During the mid-1980s separate Office Systems business units had produced a disparate range of products including IBM-compatible PCs such as the PWS (a PC/AT clone), small servers branded DRS, and various larger Unix servers sold under the Clan range. A rebranding in late 1988 pulled these together under the DRS brand, with a consistent mid-grey and peppermint-green livery.

The ICL division responsible for these systems eventually became part of the Fujitsu-Siemens joint venture.

The original DRS was the DRS 20 produced in Utica, New York and launched in September 1981. This ran the proprietary DRX (Distributed Resource Executive) operating system. The basic 'intelligent terminal' (model 10/110/210) used 8-bit 8085 processors (workstation, application and network processors), each with between 32 KB and 128 KB of memory. The Model 210 also had an 80188 application processor with 512 KB to run CP/M. The larger models 20 and 40 had floppy disk drives. The floor-standing models 50, 150, and 250 had hard disks, from which diskless models booted. In early models, these were 8" floppy disks, and later 5¼" disks.

The diskless model, that partnered the DRS 20, was the DRS 10. It had 10 KB available for applications programs developed in CIS COBOL.

Up to 16 DRS 20/DRS 10 machines could be connected via LAN with the addresses being set by DIP switches on the rear of the unit. The LAN was formed via coaxial cable in a ring formation.

The final model 310 (styled like a DRS 300 module) had a second 80186 application processor with 1 MB RAM to run Concurrent DOS, emulating an IBM PC with a Hercules screen display.

In the mid-1980s ICL developed the DRS 300 in Kidsgrove, and ran down Utica. Launched in 1986, DRS 300 was a modular system consisting of A4-sized units designed to be placed on an office bookshelf. Modules containing a power supply (Kx), processor (Ax), hard and floppy disks (Dx), streamer tape (Sx) etc. were connected by SCSI. Initial models used a 6 MHz 80286 processor (A1 module) with up to 1 MB memory. Later modules used an 8 MHz processor (A2) or 80286 with 80287 maths coprocessor (A3) with up to 4 MB, and ran Concurrent CP/M-86 and later Concurrent DOS. Although this could run code developed under CP/M, PC DOS or MS-DOS, in practice available applications were limited because many shrink-wrapped packages developed for the IBM PC made use of direct access to the (IBM) hardware. This was addressed through use of softclone technology to intercept such calls. However, this required the continual release of patches for new application versions.

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