85, 95, and 3511 Common Devices (Installing drives, memory etc.)
Opening and closing the case
Operator Panel Information

95 XP Planar
Board Revisions and P/Ns
System Firmware
95 XP Ports and Operator Panel
J4 Remote Power-ON Request
SIMM Connector Versions
Planar Limitations (or not...)
Supported MCA Features

95 XP 486 Planar FRU P/N 33F5717, different P/Ns - see below

DU1 and U55 are present on some boards but unpopulated on other - see below. Purpose currently unknown.

U22 8Kx8 SRAM (NVRAM) SRM2264LC-12 (alt) or Sony CXK5864BP-12L

Board Revisions and P/Ns

All 1S1P boards use the same FRU P/N - 33F5717. There are however multiple different board revisions, from different sources, with different P/Ns:

• 91F7441 (no U55 pads, w/ DV1, early, Greenock)
• 84F8309 (w/ U55, w/ DV1)
• 04G3888? (w/o U55, w/o DV1)
• 04G3863 (w/o U55, w/o DV1)
• 92F1480?

Early 1S1P planars (P/N 91F7441) have a slightly different layout and lack provision for U55-58. Three DIP resistor networks between slots 1 and 2 are also missing. Additionally, these boards come with quite a few bodge wires (8 total - 4 near the I/O ports, 1 next to U26, 1 near Slot 1/RN2, and 2 at the underside of Slot 2).

System Firmware (POST & BIOS)

Firmware stored on the Processor Complex.

95 XP Ports and Operator Panel

On the earliest 8595s, the power button has no shutter and is surrounded by a raised lip. On later models, the power button is covered with a shutter.

J4 Remote Power-ON Request

The J4 header can be used to turn the system on (and off) from some external source. This can be achieved by connecting pin 2 to ground (either of the remaining pins). This will only work if the hidden switch SW1 on the Op Panel has been pressed to enable the Remote Power-ON feature.

Pin 2 is directly connected to pin 29 of the nearby Op Panel connector (J3).

SIMM Connector Versions (Grey or Green)

8MB ECC SIMMs from IBM (Option P/N 92G7208, FRU P/N 92F0098) may not fit properly in the SIMM connectors of some systems.

The following system types and models are potentially affected:
   8595 - all models
   9595 - model 0LF (see note below)

Early production 8595 system boards have gray plastic SIMM connectors which physically interfere with the installation of the referenced 8 MB ECC SIMM.

Later production system boards used a green SIMM connector, which is compatible with the larger SIMMs. Many earlier systems, which have been serviced in the past 18 months, could have the later production system board (green SIMM connectors) already installed.

All system boards with green memory SIMM connectors, regardless of model number or processor upgrade are not affected.

Note: 9595 model 0LF is the only model of 9595 to use the 8595 system board, FRU P/N 92F0270, (identified by a single serial and a single parallel port).

Planar Limitations (or not...)

From the Godfather:
   Seriously: the 8595 planar is stage 3 and does not support the stage 4 "synchrostream mode", which is turned off then. It supports the normal 64-bits burst mode with up to 40 MB/s. So a Type 4 platform will be significantly slower in an old 8595-type planar than in a Server 95A planar (the one with the two serial and two parallel ports). The planar controller on the "single-LPT" planars does not return the proper values on trying to start up the SynchroStream - therefore it is not used. The only advantage left over is the faster CPU and higher calculation data throughput - and the ability to run Pentium software (if required). The overall performance is of course higher compared with e.g. the DX-50 platform - but it does not even come close to the values achieved with the same processor card in the 9595A "double LPT"-planar. At least not in a cumulative / weighted application which includes combined calculation and I/O traffic loads.

Ed. Tom: Huh? What is this "synchrostream mode" supposed to be? Also, the 64-bit streaming mode has a theoretical bandwidth of 80 MB/s, and it's definitely not a "normal" transfer mode in the PS/2 world. The T4 boards support the 32-bit 40 MB/s streaming mode. But this same mode is supported by the "M" complex and that platform was shipped together with the 1S1P planar. So there should be no difference between the two planars from this point of view... In fact, official documentation confirms that the planar itself supports streaming data transfers (up to 80 MB/s). See HERE.

For information again: The "small" 9595s model -xLx (Type 2) and -xMx (Type 3) had the old planar - all others usually had the 9595A-planar (Type 4 -xNx, -xPx, -xQx).

Ed. Checked a -xKx and -xMx planar. Same chipset, same oscillator values. Only difference was some SMD oscillators replaced metal ones. A few less logic chips (Ed. What chips exactly? I have noticed that some 1S1P boards have a PAL at position U55, and other don't. Is that it?). And the -xLx, -xMx planars are a lovely green.

Supported MCA Features

(from PS/2 Models 95 XP 486, 90 XP 486, 55LS and P75 486 Fundamentals, Oct 1990)

All of the 32-bit Micro Channel slots on the IBM PS/2 Model 90 XP 486 and Model 95 XP 486 systems are full 32-bit implementations of the Micro Channel Architecture. In addition to the basic Micro Channel features the IBM PS/2 Model 90 XP 486 and Model 95 XP 486 systems support the following enhancements to the Micro Channel architecture that were announced in November 1989:

• Data parity - This is supported on the Micro Channel for peer-to-peer transfers between supporting adapters.
• Address parity - This is supported on the Micro Channel for peer-to-peer transfers between supporting adapters.
• Streaming data procedure - This is supported up to 80 MBps using a 64 bit data path and a 100 ns cycle. It is supported on the Micro Channel for peer-to-peer transfers between supporting adapters.

These three new Micro Channel features are implemented on the planar boards of the Model 90 XP 486 and Model 95 XP 486 systems.