Editing PDP-11/44

{{Infobox computer
| name         = PDP-11/44
| image        = [[File:PDP-11X44 system in cabinet (DEC frontispiece).png|260px|frameless]]
| caption      = DEC's drawing of the PDP-11X44: the BA11-A mounting box at the top of its system cabinet
| manufacturer = Digital Equipment Corporation
| type         = 16-bit minicomputer
| release_date = 1979–1980 (sources differ)<ref name="wp" /><ref name="ug3" />
| cpu          = KD11-Z processor (M7094, M7095, M7096, M7098, M7090) with 8 KB KK11-B cache<ref name="ugt" /><ref name="chw" />
| memory       = MS11-M ECC MOS, 256 KB standard; up to 1 MB in 256 KB steps (DEC's 1981 guide); 22-bit addressing<ref name="ug11" /><ref name="ugt" />
| power        = H7140 switching supply in the BA11-A box; 90–128 V or 180–256 V, 1,350 W<ref name="ugps" />
| dimensions   = 70.15 × 48.26 × 26.34 cm (mounting box with bezel)<ref name="ugspec" />
| weight       = 32.66 kg (mounting box, unpacked)<ref name="ugspec" />
| predecessor  = PDP-11/70, PDP-11/45<ref name="wp" />
}}
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.<ref name="wp" /><ref name="chw" /> 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.<ref name="ug11" /> The KD11-Z is the last PDP-11 processor built from discrete logic chips; later models use microprocessors.<ref name="wp" /><ref name="chw" /> Wikipedia gives 1979 for the model and 1980 for its introduction; DEC's user's guide was first issued in July 1980.<ref name="wp" /><ref name="ug3" />

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.<ref name="ug12" /><ref name="ug11" /> See [[PDP-11/44 Power Supply Guide]], [[PDP-11/44 General Maintenance]] and [[PDP-11/44 Troubleshooting Guide]].

== Hardware ==
<templatestyles src="Template:StyledTable/styles.css" />
{| class="wikitable styled-table" style="width:70%; text-align:left;"
|+ '''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)
|}
<ref name="ugt" />
A microprocessor on the console interface interprets ASCII commands from the console terminal and replaces the switch-and-light console of earlier PDP-11s.<ref name="ug11" />

=== Front panel ===
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.<ref name="ugfp" />

== Documentation ==
* ''PDP-11/44 System User's Guide'', EK-11044-UG-003, 1981: [[:File:PDP-11-44 System User's Guide (EK-11044-UG-003).pdf]]
* ''PDP-11/44 System Technical Manual'', EK-KD11Z-TM-001, 1980: [[:File:PDP-11-44 System Technical Manual (EK-KD11Z-TM-001).pdf]]
* ''BA11-A Mounting Box and Power System Technical Manual'', EK-BA11A-TM-003, 1983: [[:File:BA11-A Mounting Box and Power System Technical Manual (EK-BA11A-TM-003).pdf]]
See [[PDP-11/44 Documentation]].

== Gallery ==
<gallery mode="packed" heights="200">
File:PDP-11-44 BA11-A mounting box with H7140 power supply (DEC Figure 1-2).png|The BA11-A mounting box, with the H7140 supply at the rear (DEC)
</gallery>

== Related pages ==
* [[PDP-11/44 General Maintenance]]
* [[PDP-11/44 Troubleshooting Guide]]
* [[PDP-11/44 Power Supply Guide]]
* [[PDP-11/44 Documentation]]
* [[PDP-11/70]]

== References ==
<references>
<ref name="wp">"PDP-11", ''Wikipedia'', [https://en.wikipedia.org/wiki/PDP-11 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.</ref>
<ref name="chw">"PDP-11/44" and "KD11-Z CPU", ''Computer History Wiki'', [https://gunkies.org/wiki/PDP-11/44 gunkies.org/wiki/PDP-11/44].</ref>
<ref name="ug3">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]]).</ref>
<ref name="ug11">DEC, EK-11044-UG-003, pp. 1-1 and 1-10, sections 1.1 and 1.4.</ref>
<ref name="ug12">DEC, EK-11044-UG-003, pp. 1-3 to 1-4, sections 1.2.1 and 1.2.2 and Figure 1-2.</ref>
<ref name="ugt">DEC, EK-11044-UG-003, pp. 1-5 to 1-6, Tables 1-2 and 1-3.</ref>
<ref name="ugspec">DEC, EK-11044-UG-003, p. 1-7, Table 1-4.</ref>
<ref name="ugps">DEC, EK-11044-UG-003, pp. 1-9 to 1-10, Table 1-6, H7140 specifications.</ref>
<ref name="ugfp">DEC, EK-11044-UG-003, pp. 2-1 to 2-2, Table 2-1, front panel switches and indicators.</ref>
</references>

[[Category:Digital Equipment Corporation]]