ICL DRS
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.
Modules containing a power supply (Kx), processor (Ax), hard and floppy disks (Dx), streamer tape (Sx) etc.
The display memory was exposed via a 32 KB region in the address space of the 80286 processor, requiring the selection of a single plane at any one point in time.
The card provided a resolution of 640 x 400 pixels with a 60 Hz refresh rate in conjunction with ICL's Model 307 monitor.
[9] The DRS 6000 was the result of the UNICORN project, initiated in December 1987 by the newly formed Advanced Servers Product Centre in Bracknell, to design a UNIX product for manufacture at ICL's facility in Ashton that would combine state-of-the-art technology with adherence to recognised open standards.
This product was launched in January 1990 as a multiprocessor-capable SPARC-based server, running ICL's implementation of Unix System V Release 4 (SVR4).
[11] Featuring one to four SPARC processors, up to 512 MB of RAM, 760 MB to 5 GB of storage in a single cabinet, or up to 15 GB with expansion cabinets, the DRS 6000 utilised the industry standard 32-bit VMEbus for input/output and a proprietary 64-bit HSPbus (High Speed Private bus) interfacing CPU Modules to main memory, each module providing a processor chipset and accompanying cache memory.
[12] The CPU Module was "targeted at a particular implementation of the SPARC microprocessor", running at 33 MHz, involving an "integer unit" with a stated performance rating of 15-20 MIPS, accompanied by a floating-point coprocessor.
Due to timing constraints, accesses to cache memory were not translated by a memory management unit (MMU), this being a separate component, and thus 32-bit virtual addresses were used with the cache, these being augmented by a 16-bit context number to identify distinct tasks or address spaces.
[12] As a VMEbus controller, the Central Services Module board employed a 68020 processor,[12] leading to sarcastic comments in the press that it was a DRS 400 in disguise.
[citation needed] In 1993, ICL upgraded the DRS 6000 300 series with a 40 MHz SuperSPARC processor, introducing DRS/NX Version 7.0, an implementation of Unix System V Release 4.2.
In 1987, the DRS Professional Work Station (PWS) was ICL's first foray into IBM PC/AT compatible computing.
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 capable of communicating with ICL departmental and mainframe services using a combination of Microlan2 and OSLAN (Open Systems Local Area Network) protocols.
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, Sybase and Progress 4GL supplied by Progress Software.
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.
