The Honeywell Level 6 was a line of 16-bit minicomputers, later upgraded to 32-bit, manufactured by Honeywell, Inc. from the mid 1970s. In 1979 the Level 6 was renamed the DPS 6, subsequently DPS 6 Plus and finally DPS 6000.
Description
As initially introduced the Level 6 consisted of three models: the 6/06, the 6/34, and the 6/36. The CPU featured a real-time clock, a ROMbootstrap loader and 64 interrupt levels. The architecture provided a variety of addressing modes and 18 programmer-visible registers. Rack-mount and tabletop versions were available. These systems supported up to 64 K words of MOS memory with a cycle time or 650 nanoseconds. All three models all featured the Megabus, which was a proprietary asynchronous bus architecture. By 1978 the line had been extended downwards with the introduction of the 6/23 and 6/33, and upwards with the 6/43, 6/47, 6/53, and 6/57. The 6/23 did not support the Megabus. The 6/33 was the new entry-level upgradable model. The other four models supported up to 1 MW of memory and 26 registers. A memory management unit, optional on the 6/43 and 6/47, and standard on the 6/53 and 6/57, supported memory segmentation and four protection rings. An optional Scientific Instruction Processor added single- and double-precision hardware floating-point instructions. The 6/47 and 6/57 were enhanced versions of the 6/43 and 6/53 respectively which added a Commercial Instruction Processor including 30 additional instructions for character-string manipulation and decimal arithmetic. Among the final developments in the line were the high-end 32-bit 6/95-1, 6/98-1 and dual processor 6/95-2 and 6/98-2 models. In the 1980s, Honeywell's Datanet 8 line of communications processors, often used as front-end processors for DPS 8 mainframes, shared many hardware components with DPS 6. Another specialised derivative of the Level 6 was the Honeywell PagePrinting System. In June 1986, following Honeywell Information Systems' merger with Bull, Honeywell Bull introduced the DPS 6 Plus line of symmetric multiprocessing 32-bit systems, models 410 and 420 with up to four processors.In 1987 they introduced the uniprocessor models 210 and 220, announced the HRX, and Computerworld reported that there were more than 50,000 DPS 6 systems installed worldwide. The HRX was introduced as the DPS 6000 600 series. Recognising the commercial success of Unix, in 1988 Honeywell Bull introduced an 80386-based Unix co-processor for the DPS 6 Plus 400 series.
