ICL DRS

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 (an 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.

DRS 20/100/200

An ICL DRS20 terminal

The original DRS was the DRS 20 produced in Utica, New York and launched in 1982. 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 32K and 128K of memory. The Model 210 also had an 80188 application processor with 512K 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 disk-less models booted. In early models these were 8" floppy disks, and later 5¼" disks.

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

DRS 300

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 an 8 MHz 80286 processor (A2 module) or 80286 with 80287 (A3) and ran Concurrent CP/M-86 and later Concurrent DOS.^[1] 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.^[2] However this required the continual release of patches for new application versions.

The initial DRS 300 also ran ICL's implementation of Unix System V Release 2, DRS/NX V2. Later an 80386 (A4) module was added, to run a 32-bit DRS/NX V3, based on System V Release 3.

DRS 400, DRS 500

These brand names were applied to bought-in Unix boxes. The DRS 400 originated as the Clan 4, based on the Motorola 68020 running UniSoft's Uniplus Unix. This was later replaced by the DRS 400E, based on the Motorola 68030 running DRS/NX V3. DRS 500 originated as the Clan 5, 6 and 7 based on the CCI Power 6/32. This was built in Irvine by CCI, which had been taken over by ICL's parent STC PLC. CCI was also the source of what became ICL's flagship OfficePower office application suite across the DRS range.

DRS 3000

The successor to DRS 300, the DRS 3000 was an IBM-compatible, 80486-based, floor-standing model running SVR4. The Pentium-based Level 656 was launched in September 1993.^[3]

DRS 6000

The in-house (Irvine/Bracknell) developed DRS 6000 was launched in January 1990 as a washing machine-sized SPARC-based server, running ICL's implementation of Unix System V Release 4 (SVR4). It also had a 68020-based Central Service Module board (CSM), leading to sarcastic comments in the press that it was a DRS 400 in disguise. By 1992 there were desktop, slimline and full sized models, ranging from a single-processor desktop model rated at 29 MIPS (L240) to a 4-processor model rated at 116 MIPS (L644). Some models were sold by Fujitsu as the DS/90. ICL received the Queen's Award for Export Achievement for DRS 6000 in 1993.

The DRS 6000 competed directly with IBM's RS/6000, which was launched a few weeks later; originally planned to be called the Drs 600 it was renamed when it was found that IBM had decided on the RS 6000.

In 1994 the DRS range was superseded by the SuperServer (Ks (SPARC) and Ki (Intel)) and TeamServer (Es (1-2 SPARC CPUs), Hs (2-4 SPARC CPUs), Ei (1 x86 CPU), Hi (2 x86 CPUs)) ranges of SPARC and Intel-based machines, running DRS/NX Unix or Microsoft Windows NT.

• DRS 6000 Level 200 Series ^[4]

• DRS 6000 Level 600 Series^[5]

DRS PWS

In 1987 the DRS Professional Work Station (PWS) was ICL's first foray into IBM PC AT compatible computing. The DRS PWS was initially released with MS-DOS 4.0 (not to be confused with the later public releases of IBM DOS 4.0 in July 1988 and MS-DOS 4.01 in November 1988). This was a real-mode pre-emptive multi-tasking version of MS-DOS 2.0 and was also the forerunner of OS/2. It was soon replaced with MS-DOS 4.1 when this became available; this was written especially for the DRS PWS but was not finished for the launch ^[6]. Microsoft agreed to write a custom version of MS-DOS 4.0 for ICL that would take advantage of the extra memory on the ICL computers. As a consequence PWS users had a number of software compatibility challenges, although the PC Business Unit (PCBU) at ICL BRA04, in Bracknell, did patch some applications for larger customers.

The PWS was positioned to compete with the IBM Personal System/2 (PS/2) and the DEC Vaxstation 2000. In 1988 the DRS PWS and DRS PWS 386 were respectively rebranded as the DRS Model 60 and DRS Model 80 ^[7].

The PWS hardware was a large desktop or floor standing tower chassis, running on an Intel 8 MHz 80286 processor that was later superseded by an Intel 80386 (DRS PWS 386). Memory expansion was via proprietary cards (1Mbyte or 4Mbyte cards, 16Mbyte total) and initially there was no support for 1.44 Mbyte High Density (HD) floppy drives, although a hardware modification to the clock lines on the floppy disk controller meant that later versions of the PWS could be upgraded. The ENGA (EGA compatible video) controller, displayed standard EGA graphics and text with an additional line reserved on the bottom row for multi-tasking and communications task messages.

The PWS was capable of communicating with ICL departmental and mainframe services using a combination of Microlan2 and OSLAN (Open Systems Local Area Network) protocols. Microsoft and OSLAN network connectivity was supported via BICC OSLAN cards (OSLAN being ICL's implementation of OSI transport protocols over Ethernet). TCP/IP and DECnet support was implemented by third parties using packet drivers, as NDIS was not available at this time.

Development software

Languages on DRS20 under DRX included Microsoft BASIC, Micro Focus CIS-COBOL and Pascal, and application building packages including Userbuild and the Demon suite.

Languages on DRS300 Concurrent DOS included Lattice C, CBASIC, Micro Focus Level II COBOL and Digital Research languages including FORTRAN and Pascal.

Development software on the Unix-based DRS ranges (300 to 6000) included C, Micro Focus and RM COBOL, EPC C++, FORTRAN and Pascal, and relational databases including Ingres, Informix, Oracle and Sybase.

During this period, ICL's software strategy was increasingly to make available on its own hardware popular software packages developed by third parties. Almost invariably this involved porting the source code, as there was insufficient compatibility between machines at the binary level. In order to reduce the cost of this activity, and the commercial disadvantage of not having as large a software portfolio as rival vendors, ICL invested strenuous efforts to improve cross-industry compatibility through initiatives such as X/Open.

Notes

1. ^ Steve Malone (July 1986). "ICL DRS-300 Multi-User by Stages". Practical Computing 9 (7): pp. 48-51. 
2. ^ Steve Malone (July 1986). "Softcloning". Practical Computing 9 (7): p. 73. 
3. ^ New Pentium Processor System for Unix, Product Matters Issue 3 September 1993, International Computers Ltd, Bracknell
4. ^ Model 240: Cabinet type: Compact Desktop Processor 1 x 40 MHz SCSI Channels 1 Floppy disk (fmt) 720Kbyte & 1.44Mbyte Disk 1 x 520Mbyte Specifications: Processor - Type SPARC/RISC - Word Length 32 bits - Cache 64 Kbytes - Cache configuration 64k (2k x 32) direct mapped Memory - Size (module) 8Mbyte, 16Mbyte - Size (max) 96Mbyte - Access time 80ns Mbus - Cycle time 25ns - Data path width 64bits - Memory slots 6 pairs - Transfer rate 320Mbyte/sec Sbus - Slots 5 - Cycle time 40ns - Data path width 32bits - Transfer rate 100Mbyte/sec
5. ^ Model 630: Cabinet Type: Midi Processor: 1 x 33 MHz Performance: 23 MIPS SCSI Channels: 2 Disks: 1 x 660Mbyte Model 632: Cabinet Type: Midi Processor: 2 x 33 MHz Performance: 46 MIPS SCSI Channels: 2 Disks: 1 x 660Mbyte Model 640: Cabinet Type: Midi Processor: 1 x 40 MHz Performance: 29 MIPS SCSI Channels: 2 Disks: 1 x 660Mbyte Model 642: Cabinet Type: Midi Processor: 2 x 40 MHz Performance: 58 MIPS SCSI Channels: 2 Disks: 1 x 660Mbyte Model 644: Cabinet Type: Midi Processor: 4 x 40 MHz Performance: 116 MIPS SCSI Channels: 2 Disks: 1 x 660Mbyte Specifications: Processor - Type SPARC/RISC - Word Length 32 bits - Cache 128 Kbytes - Cache configuration 16k x 64 direct mapped Memory - Size (module) 16Mbyte, 32Mbyte, 64Mbyte, 128Mbyte - Size (max) 512Mbyte - Transfer rate 66Mbyte/sec (reads) 88Mbyte/sec (writes) Disk - Size 5.25" - Max 8Gbyte (main cabinet) 29Gbyte (with expansion cabinets) HSPbus - Cycle time 60ns - Data Path Width 64 bits - Slots 9 - Transfer rate 133Mbytes/sec VMEbus - Slots 11 (main cabinet) 31 (with 2 expansion cabinets) - Throughput 40Mbyte/sec (Sources: Product description glossy's)
6. ^ "ICL launches DRS 300 80286 Professional Workstation with multi tasking MS-DOS 4.1". Computer Business Review. 20 September 1987. http://www.cbronline.com/news/icl_launches_drs_300_80286_professional_workstation_with_multi_tasking_ms_dos_41. Retrieved 22 Sept 2011. 
7. ^ "ICL recasts DRS line to embrace its Clan Unix systems". Computer Business Review. 29 September 1988. http://www.cbronline.com/news/icl_recasts_drs_line_to_embrace_its_clan_unix_systems. Retrieved 22 Sept 2011.