Honeywell 6000 series

The high-end model was the 6080, with performance approximately 1 MIPS. Smaller models were the 6070, 6060, 6050, 6040, and 6030. In 1973, a low-end 6025 was introduced.[1] The even-numbered models included an Enhanced Instruction Set feature (EIS), which added decimal arithmetic and storage-to-storage operations to the original word-oriented architecture.[2]

In 1973, Honeywell introduced the 6180, a 6000-series machine with addressing modifications to support the Multics operating system. In 1974, Honeywell released the 68/80 which added cache memory in each processor and support for a large (2-8 million word) directly addressable memory.[3] In 1975, the 6000-series systems were renamed as Level 66, which were slightly faster (to 1.2 MIPS) and offered larger memories. In 1977, the line was again renamed 66/DPS, and in 1979 to DPS-8, again with a small performance improvement to 1.7 MIPS.[4] The Multics model was the DPS-8/M.[5]

A Honeywell Level 66/60 mainframe computer with its cabinet door open

6000-series systems were said to be "memory oriented" — a system controller in each memory module arbitrated requests from other system components (processors, etc.). Memory modules contained 128 K words of 1.2 μs 36-bit words; a system could support one or two memory modules for a maximum of 256 K words (1 MB of 9-bit bytes). Each module provided two-way interleaved memory.

Devices called Input/Output Multiplexers (IOMs) served as intelligent I/O controllers for communication with most peripherals. The IOM supported two different types of peripheral channels: Common Peripheral Channels could handle data transfer rates up to 650,000 cps; Peripheral Subsystem Interface Channels allowed transfers up to 1.3 million cps.

The 6000 supported multiple processors and IOMs.[6] Each processor and IOM had four ports for connection to memory; each memory module had eight ports for communication with other system components, with an interrupt cell for each port.[7]

Memory protection and relocation was accomplished using a base and bounds register in the processor, the Base Address Register (BAR). The IOM was passed the contents of the BAR for each I/O request, allowing it to use virtual rather than physical addresses.

A variety of communications controllers could also be used with the system. The older DATANET-30 and the DATANET 305— intended for smaller systems with up to twelve terminals attached to an IOM.[8] The DATANET 355 processor attached directly to the system controller in a memory module and was capable of supporting up to 200 terminals.

The CPU operated on 36-bit words,[9] and addresses were 18 bits. The Accumulator Register (AQ) was 72 bits, or could be accessed separately as two 36-bit registers (A and Q) or four 18-bit registers (AU,AL,QU,QL). An eight-bit Exponent Register contained the exponent for floating point operations (the mantissa was in AQ). There were eight eighteen-bit index registers X0 through X7.[10]

The 18-bit Base Address Register (BAR) contained the base address and number of 1024-word blocks assigned to the program (the 6180 used segmentation rather than the BAR). The system also included several special-purpose registers: an 18-bit Instruction Counter (IC) and a 27-bit Timer Register (TR) with a resolution of 2 μs. Sets of special registers were used for fault detection and debugging.

The EIS instruction set added eight additional 24-bit registers AR0 through AR7. These registers contained an 18-bit word address, a 2-bit address of a character within the word, and a 4-bit address of a bit within the character.

  Address register format:
                     1 11 2  2
   0                 7 89 0  3
  +-------------------+--+----+
  |      Word         | C| Bit|
  +-------------------+--+----+

  Basic instruction format:
                          1 1       2 2 2 2    3
        0                 7 8       6 7 8 9    5
       +-------------------+-----------+-+------+
       |          Y        |  OP       |I| Tag  |
       +-------------------+-----------+-+------+

  EIS instruction format:
                          1 1       2 2 2 2    3
 word   0                 7 8       6 7 8 9    5
       +-------------------+-----------+-+------+
   0   |  Variable field   |  OP       |I| MF1  |
       +-------------------+-----------+-+------+
   1   |  Operand descriptor 1 or indirect word |
       +----------------------------------------+
   2   .  Operand descriptor 2 or indirect word . (optional)
       +- - - - - - - - - - - - - - - - - - - - +
   3   .  Operand descriptor 3 or indirect word . (optional)
       +- - - - - - - - - - - - - - - - - - - - +

The following peripherals were available for the 6000-Series machines in 1971.[8]

• Control console, attached to the IOM, was a printer-keyboard that operated at 15 characters per second (cps).
• DSS180 removable disk storage subsystem provided up to 18 drives using disks physically compatible with IBM 2316 disks used in the 2314.[13] The disks were formatted to provide 384 six-bit characters per sector and 27,648,000 characters per pack. The average seek time was 34 milliseconds (ms) and data transfer rate was 416,000 cps.
• DSS190 removable disk storage subsystem provided up to 16 drives using disks compatible with IBM 3336-11 drives used in the 3330. The disks were formatted with variable-length sectors in multiples of 384 characters. One pack could hold up to 133,320,000 characters. The average access time was 30 ms and data transfer rate was 1,074,000 cps.
• DSS270 disk storage subsystem provided up to 20 modules of head-per-track disk. Capacity per module was 15.3 million characters. Average access time was 26 ms, and maximum transfer rate was 333,000 cps.
• DSS167 disk storage subsystem allowed up to eight online disk drives plus an offline spare. Per disk capacity was 15 million characters; average access time was 87.5 ms and data transfer rate was 208,000 cps.
• DSS170 removable disk storage subsystem allowed up to eight online disk drives plus an offline spare. Per disk capacity was 27.5 million characters; average access time was 72.5 ms and data transfer rate was 416,000 cps.
• Magnetic tape was available in a variety of models, all using open-reel ½ inch magnetic tape. Various models could read and write seven-track or nine-track tape with densities from 200 bits per inch (bpi) to 1600 bpi at rates of 37.5 inches per second (ips) to 150 ips. The maximum transfer rate was 266 characters per second (cps). All models connected to the system through the IOM.
• Line printers were the PRT300 train printer capable of printing at 1150 lines per minute (lpm) and the PRT201 at 1200 lpm.
• Punched card equipment consisted of the CRZ201 card reader capable of reading up to 900 80-column cards per minute (cpm) and the CPZ201 card punch which could punch up to 300 80-column cards per minute.

The primary operating system for the line was the General Comprehensive Operating System (GCOS), which Honeywell originally inherited from General Electric's GECOS. In 1978 Honeywell introduced a rewritten version GCOS 8, which supported virtual memory. The Multics OS also ran on selected CPU models.[14][15]

In 1974, Honeywell purchased Xerox Data Systems (XDS), and developed a work-alike of the Xerox operating system CP-V as CP-6 to run on DPS-8 systems in order to retain Xerox' loyal customer base.[4]

• Open source emulator for the GE Large Systems / Honeywell / Bull 600/6000‑series mainframe computers
• Honeywell DPS8 manuals at Bitsavers
• Computer History Wiki - Honeywell 6000 series
• Multics and Related 6000 Series Front Panels