8642 Planar

84h7085.exe PC Server 720 reference diskette v1.12 (zipped image)
4227103.exe PC Server 720 diagnostic diskette v1.13 (zipped image)
720pci.exe PC Server 720 PCI Configuration Diskette (zipped files)
4305348.exe PC Server 720 BIOS flash update level 14 v1.10
4305348a.txt README file for BIOS flash update level 14 v1.10
   Note: BIOS 10 and diags 1.12 and later properly reset memory cache after testing
720svga.exe PC Server 720 SVGA support diskette v1.01 (CLMODE)
720svga.txt Readme for 720svga.exe

195-071 IBM PC Server 720 with ServerGuide and Related Options

PC Server 720 User's Reference, 1st Ed. (Jul 1995)

720 Planar
Reverse Polarized SMD Capacitor on Video
Buses and Bridges

PC Server 720 Planar FRU P/N 06H1810 (component IDs by Tim Clarke)

J?? Serial ports header
J24 PCI bus speed select
J25 Remote update (CE use only)
JMP2 Password write-enable
JMP4 Power-on features
JMP5 ROM bank select
U1 14.3181 MHz osc
U2,3 Cypress CY78991-7JC
U4 100 MHz clock for J4 div. selection?
U5 DECchip, D7526C, 21050, VY06867
U6 06H5425 PCI-MCA bridge?
U7,8 NEC 42S4260-70 video RAM
U9 ROM 06H7206 Rev. 1 (video)
U10 06H3195
U11 53G0520
U12 Cirrus Logic CL-GD5429-86QC-C
U13 06H2906
U14 06H8922
U15 ROM 75H8834 (system BIOS?)
U16 Sony CX581000AM-70 RAM?
U17 ROM 75H8835 (system BIOS?)
U18 75H0154
U19 40.0000 MHz osc
U20 Cypress CY78991-7JC
U21,22 Power transistors
U23 22.184 MHz osc
U24 Power transistor, well heatsinked
U25 Dallas DS1230Y-70 32Kx8 NVRAM
U26 Dallas DS1587 RTC/CMOS + 8Kx8 NVRAM
U27 82078SL Floppy controller
U28 24.0000 MHz osc
U29 Xilinx XC3042-100 FPGA
U30 (Phillips) 07H0560 Rev. 1

U6 06H5425 PCI-MCA bridge? Also used on the PC 730/750 MCA riser and the PC 720 riser.

Reverse Polarized Capacitor on Video

Note: (from Tim) The C7 capacitor on the reverse side of the planar near the video port is the WRONG WAY ROUND, as with many IBM implementations of the CL-GD542x video controllers. If you have one of these Server 720s the video output will be dim and will eventually flicker for a fair while and then finally DIE!!! That's happened to this planar and is on-going with the one I replaced this one with. BE WARNED!!!

Just like on the Short 1MB SVGA, there is a reversed capacitor on the planar. This is the original INCORRECT orientation with the positive side of C7 towards the video port.

Buses and Bridges (source page 45 phys., edited)

The PC Server 720 incorporates three bus architecture designs.

C-bus II - Multiprocessing Bus

The C-bus II multiprocessing bus is a 64-bit bus that provides symmetric multiprocessing (SMP) capabilities. It supports up to six processor boards and has a peak-data-transfer rate of 400 MB/s.

Any processor board connected to the C-bus II multiprocessing bus can be assigned any application task, and all processor boards connected to this bus can globally access the system memory and the input/output (I/O) devices in the server.

The multiprocessor-to-PCI bus bridge connects the C-bus II multiprocessing bus to the PCI bus. This bus bridge provides a path through which the microprocessors can directly access PCI devices mapped anywhere in memory or address spaces.


The PCI bus is a 32-bit local bus that provides a high-speed data path between the processor boards and peripheral devices, such as the video and hard disk subsystems. This bus uses the burst mode for all data transfers. For 32-bit PCI devices, the PCI bus supports a peak-data-transfer rate of 132 MB/s. It supports PCI bus speeds up to 33 MHz, and allows PCI masters direct access to system memory.

Expansion slots 1 through 5 are the secondary PCI bus slots. Slots 6 and 7 are the primary PCI bus slots; you should install your high-performance PCI devices in these slots. Slot 8 contains the multiprocessor-to-PCI bus bridge.

The PCI bus coexists with the Micro Channel bus, which means that you can install up to seven PCI, Micro Channel, or a mixture of PCI and Micro Channel adapters in the expansion slots.

An integrated circuit (chip) on the system board connects the PCI bus to the Micro Channel bus.

Micro Channel Bus

The Micro Channel bus serves as an expansion bus. Like the PCI bus, the Micro Channel bus also supports burst data transfers, in which data is sent in multiple bytes with no intervention by the microprocessor. The Micro Channel bus also supports streaming-data transfers of up to 80 MB/s.

The Micro Channel bus provides features not implemented in the PCI bus. These include the streaming-data procedure, channel-check reporting, and error logging.

Content created and/or collected by:
Louis F. Ohland, Peter H. Wendt, David L. Beem, William R. Walsh, Tatsuo Sunagawa, Tomáš Slavotínek, Jim Shorney, Tim N. Clarke, Kevin Bowling, and many others.

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