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PDP-11/44

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PDP-11/44
DEC's drawing of the PDP-11X44: the BA11-A mounting box at the top of its system cabinet
Specifications
ManufacturerDigital Equipment Corporation
Type16-bit minicomputer
Released1979–1980 (sources differ)[1][2]
CPUKD11-Z processor (M7094, M7095, M7096, M7098, M7090) with 8 KB KK11-B cache[3][4]
MemoryMS11-M ECC MOS, 256 KB standard; up to 1 MB in 256 KB steps (DEC's 1981 guide); 22-bit addressing[5][3]
Storage—
Display—
Sound—
PowerH7140 switching supply in the BA11-A box; 90–128 V or 180–256 V, 1,350 W[6]
Dimensions70.15 × 48.26 × 26.34 cm (mounting box with bezel)[7]
Weight32.66 kg (mounting box, unpacked)[7]
OS / Firmware—
PredecessorPDP-11/70, PDP-11/45[1]

The PDP-11/44 is a Digital Equipment Corporation Unibus minicomputer built around the KD11-Z processor, sold as a lower-cost successor to the PDP-11/70 and PDP-11/45.[1][4] It runs the complete PDP-11/70 instruction set except the FD MAINT INST instruction, adds the MFPT and CSM instructions, and provides 22-bit memory addressing.[5] The KD11-Z is the last PDP-11 processor built from discrete logic chips; later models use microprocessors.[1][4] Wikipedia gives 1979 for the model and 1980 for its introduction; DEC's user's guide was first issued in July 1980.[1][2]

The whole computer fits in a single 10½-inch BA11-A mounting box with a 14-slot backplane, three fans, a foam air filter behind the front bezel and an H7140 switching power supply at the rear; the PDP-11X44 puts that box at the top of a 40-inch cabinet with a dual TU58 cassette drive.[8][5] See PDP-11/44 Power Supply Guide, PDP-11/44 General Maintenance and PDP-11/44 Troubleshooting Guide.

Hardware

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PDP-11/44 standard hardware and options (EK-11044-UG-003, Tables 1-2 and 1-3)
Item Description
KD11-Z processor M7090 console interface, M7094 data path, M7095 control, M7096 multifunction (console and TU58 serial lines, line clock), M7098 Unibus interface
KK11-B 8 KB cache on a hex module (M7097)
MS11-MB 256 KB ECC MOS memory on a hex module; MS11-MC has 512 KB on two modules
BA11-AA / BA11-AB Mounting box for 120 V or 240 V, with H7140 power supply and KD11-Z backplane (70-16502)
FP11-F Floating-point processor (M7093), option
KE44-A Commercial instruction set processor (M7091 and M7092), option
H7750-BA / -BD Battery backup unit for 120 V or 240 V, option
TU58 Dual cassette tape drive, 256 KB per cassette (standard on the PDP-11X44)
872-D / 872-E Power controller (PDP-11X44 cabinet)

[3] A microprocessor on the console interface interprets ASCII commands from the console terminal and replaces the switch-and-light console of earlier PDP-11s.[5]

Front panel

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The control panel on the bezel has a four-position keyswitch (DC OFF, LOCAL, LOC DSBL, STD BY), a HALT/CONT/BOOT toggle, and RUN, DC ON, BATT and REMOTE indicators. DC OFF removes DC power and stops the fans but does not remove AC from the system; only unplugging the line cord does. STD BY switches off the main +5 V, +15 V and −15 V while keeping the memory voltages and fans running.[9]

Documentation

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See PDP-11/44 Documentation.

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  • The BA11-A mounting box, with the H7140 supply at the rear (DEC)
    The BA11-A mounting box, with the H7140 supply at the rear (DEC)
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References

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  1. ↑ 1.0 1.1 1.2 1.3 1.4 "PDP-11", Wikipedia, en.wikipedia.org/wiki/PDP-11, models list: PDP-11/44 (1979), "introduced in 1980" as a replacement for the 11/45 and 11/70; last PDP-11 processor built from discrete logic.
  2. ↑ 2.0 2.1 Digital Equipment Corporation, PDP-11/44 System User's Guide, EK-11044-UG-003, July 1981, edition notice: first edition July 1980 (File:PDP-11-44 System User's Guide (EK-11044-UG-003).pdf).
  3. ↑ 3.0 3.1 3.2 DEC, EK-11044-UG-003, pp. 1-5 to 1-6, Tables 1-2 and 1-3.
  4. ↑ 4.0 4.1 4.2 "PDP-11/44" and "KD11-Z CPU", Computer History Wiki, gunkies.org/wiki/PDP-11/44.
  5. ↑ 5.0 5.1 5.2 5.3 DEC, EK-11044-UG-003, pp. 1-1 and 1-10, sections 1.1 and 1.4.
  6. ↑ DEC, EK-11044-UG-003, pp. 1-9 to 1-10, Table 1-6, H7140 specifications.
  7. ↑ 7.0 7.1 DEC, EK-11044-UG-003, p. 1-7, Table 1-4.
  8. ↑ DEC, EK-11044-UG-003, pp. 1-3 to 1-4, sections 1.2.1 and 1.2.2 and Figure 1-2.
  9. ↑ DEC, EK-11044-UG-003, pp. 2-1 to 2-2, Table 2-1, front panel switches and indicators.
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