Editing IBM PS/2 Model 80 (section)

== Planar ==

* '''Processor.''' 80386DX soldered or socketed on the planar — U13 on the Type 1, U131 on the Type 2, U96 on the Type 3 — with a socket for an 80387DX beside it.<ref name="at8580t1" /><ref name="at8580t2" /><ref name="at8580t3" />
* '''Cache.''' None on the 16 and 20 MHz planars. The 25 MHz planar carries an Intel 82385-25 cache controller (U54) and eight Mitsubishi M5M5178P-33 8 K × 8 SRAMs, giving 64 KB of L2.<ref name="at8580t3" /><ref name="qref80" />
* '''Memory.''' Two '''memory-expansion connectors''' on the planar — J15 and J16 on the 16/20 MHz boards, J8 and J9 on the 25 MHz board — which take IBM's own 80386 planar memory cards. '''These are not 72-pin SIMM sockets and PS/2 SIMMs do not fit them.''' The 16 and 20 MHz planars take 1 MB and 2 MB 80 ns cards to a board maximum of 4 MB; the 25 MHz planar supports 8 MB using 4 MB System Memory Boards. Beyond that, memory goes on Micro Channel adapters, to a system ceiling of 16 MB.<ref name="at8580mem">[https://www.ardent-tool.com/8580/Memory.html 8580 Planar Memory], Ardent Tool of Capitalism. Catalogue of the IBM planar memory cards used in the 8580's two on-board memory-expansion connectors, with part numbers, DRAM complements and the connector pinout. These cards are specific to the Model 80 and are not 72-pin SIMMs.</ref><ref name="at8580t1" /><ref name="at8580t3" /><ref name="qref80" />
* '''Real-time clock.''' A '''Motorola MC146818A''' soldered to the planar — U187 on the Type 1, U186 on the Type 2, U132 on the Type 3 — with a 32.768 kHz crystal beside it, plus a separate 2 K × 8 SRAM holding the Micro Channel configuration. '''There is no Dallas RTC module on this planar and no battery inside the clock chip.'''<ref name="at8580t1" /><ref name="at8580t2" /><ref name="at8580t3" />
* '''Battery.''' A separate 6 V two-cell lithium pack, FRU 72X8498, in the battery/speaker assembly FRU 33F5950, connected to the planar at J18 (Type 1 and 2) or J19 (Type 3).<ref name="atbatt">[https://www.ardent-tool.com/misc/Battery_Speaker_Assembly.html Battery/Speaker Assembly], Ardent Tool of Capitalism. Source for the assembly FRU 33F5950, the battery FRU 72X8498, both connector pinouts (speaker data, ground, +6 V battery, Clear POP) and the power-on-password clearing procedure for Models 50, 50 Z, 60, 65 SX, 70 and 80.</ref><ref name="atbattx">[https://www.ardent-tool.com/misc/batteries.html PS/2 Batteries], Ardent Tool of Capitalism, based on content by Bob Eager and Peter H. Wendt. Cross-reference of PS/2 models to battery types: the Model 70 and the Model 80 both take FRU 72X8498, a 6 V two-cell lithium pack equivalent to a CR-P2 / DL223A / EL223AP / K223LA / PC223 camera battery.</ref>
* '''Video.''' VGA on the planar — a 72X8287 or 90X8941 VGA controller, an INMOS IMSG171 RAMDAC and eight 64 K × 4 DRAMs for 256 KB of video memory. 720 × 400 in text mode, 640 × 480 in graphics, 256 colours or 64 shades of grey. Composite video is not supported.<ref name="at8580t1" /><ref name="at8580t2" /><ref name="atcommon80" />
* '''Fuses.''' The 25 MHz planar carries three: F2 at 1 A, F3 at 1.5 A and F4 at 2.0 A, with pads for a fourth.<ref name="at8580t3" />
* '''Ports.''' VGA (HD15), serial (DB-25), parallel, auxiliary device and keyboard along the rear edge. The 25 MHz machines' parallel port supports DMA transfers.<ref name="at8580t1" /><ref name="a190055" />

'''Warning.''' Some non-IBM graphics adapters '''drive''' the VGA signals rather than receiving them. Fitting two adapters that both drive VGA will damage both.<ref name="atcommon80" />