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. The initial DRS 300 also ran ICL's implementation of Unix System V Release 2, DRS/NX V2, though that was never released commercially. 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 P5 Pentium-based Level 656 was launched in September 1993. 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 In 1994, the DRS range was superseded by the SuperServer (Ks (SPARC) and Ki (Intel)) and TeamServer (Es