320/520 PCI/MCA Planar

rfpcimca.exe 320 / 520 Reference Diskette v2.07 (zipped image)
rdpcimca.exe 320 / 520 Micro Channel Diagnostic Disk v5.30 (zipped image)
33l3917.exe 320 / 520 Micro Channel BIOS Flash Update Disk v29A (readme) (zipped image)
m30h2591.exe 320 and 520 OS/2 Video Support Disk v1.23
m30h2594.exe 320 / 520 Windows and Utilities Video Support v1.23 (1/2)
m30h2597.exe 320 / 520 Windows and Utilities Video Support v1.23 (2/2)
mcantsmp.exe 320 / 520 NT SMP Support Diskette for MC v1.0 (readme)
m84h4257.exe 320 / 520 NT Spt Disk for Cirrus Logic 5436 Video v1.01

Level E Planar
Planar Variants and CPU Speeds
Locating CPU Jumpers
CPU Speed Settings

All 320/520 MCA planars made by Micronics?


Intel Neptune 82434NX PCMC chipset, PCI 2.0 (2 slots)


16/256 MB (std/max), 70 ns 72-pin SIMMs w/ gold contacts
Supports 4, 8, 16, 32 MB industry-standard parity or EoS (ECC-on-SIMM) SIMMs
All memory must be installed in matched pairs due to 64 bit path to memory
All memory addressable by DMA


256/512 KB shared L2 cache w/ full SMP support
Asynchronous, write-back, directly mapped; 15 ns

Level E Planar FRU P/N 96G3694 (no J1) [P]

BT1 CR2032 battery holder
HT1 Voltage regulator
J2 SCSI LED connector (yellow/white)
J3 IDE HD LED connector (red/white)
J4 Front fan connector (black/red)
J5 L2 Cache
J6 Speaker connector
J8 Primary CPU fan connector
J9 Secondary CPU fan connector
J10 Power LED connector (green/white)
J12 Clock multiplier
J13 IDE connector pads
J14 Memory card
J15 Password write
J16 C2 cover open
J17 C2 keylock
J19 Parallel port header
J20 Floppy header
J21 Serial B header
J23 Power connector pads
J24 Serial A header
J25 Reset switch header
J26 SCSI Select
J27 Video Select
J28 SCSI standard connector
J35 SCSI F/W connector
J38 Power connector
J39 External SCSI F/W connector
J40 Video connector
J41 Keyboard port
J42 Mouse port
J43 CPU clock speed
U1 Primary CPU socket
U13 Intel S82434NX
U25,30 Intel S82433NX
U27 OKI M33S0570-33 06H3669
U28 Secondary CPU socket
U29 06H6119 TI CF64569BPPM
U31 Flash BIOS
U57 06H5685

The EPRM has the pinout and use for the various settings.

J12 - CPU Clock Multiplier


J15 - Password Write


J26 - SCSI Select

System Board1-2 (default)
Installed Adapter2-3

J27 - Video Select

System Board1-2 (default)
Installed Adapter2-3

J43 - FSB Clock

50 MHz3-4, 5-6
60 MHz1-2, 5-6
66 MHz1-2, 3-4

Planar Variants and CPU Speeds

For the PC Server 320 MCA systems, there are two planar FRUs:

  • FRU P/N 96G1340 supports 75 and 90 MHz only.
  • FRU P/N 96G3694 supports 75, 90, 100, and 133 MHz.

For the PC Server 520 MCA systems, there is one planar FRU:

  • FRU P/N 96G2648 supports 75, 90, 100, and 133 MHz.

In addition there are two versions of 96G3694 and 96G2648:

  • Original planar (Level D & E): No J1, J12 (2-pin), J43 (6-pin).
  • New planar (Level G): J1 (3-pin), J12 (3-pin), J43 (6-pin).

On the new planar (Level G), a new jumper J1 (3-pin) was added AND J12 was changed from a 2-pin to a 3-pin jumper. Jumpers J1, J12 and J43 control the processor speed.

Locating CPU Jumpers

J1 (new planar) is located to the left of the processor and J12.
J12 is located to the left of the processor.
J43 is located a little less than halfway down the system board beneath the processors. It has three double jumpers (6-pins) corresponding to each oscillator located right beneath the processors. The three oscillators from left to right are 50, 60, and 66 MHz. When you jumper the pins, you are grounding its corresponding oscillator thus disabling it.

The earlier Level D and E planar had a J43 consisting of 2x3 pins and J 12 of 2 pins. The Level G planar had a J43 with 2x3 pins, J12 with 3 pins and J1 with 3 pins.

Level D and E Planar
1 °  ° 2
3 °  ° 4
5 °  ° 6
 (J43)    1 °
          2 °
Level G Planar
1 °  ° 2
3 °  ° 4
5 °  ° 6
 (J43)  1 °   1 °
        2 °   2 °
        3 °   3 °
       (J1)  (J12)

The diagram above indicate the pin orientation and numbering scheme with respect to the edge of the planar. Refer to the diagram on the system frame or door for additional information.

CPU Speed Settings

Original Levels
Level D Level E Level G
FRU P/N 96G1340 (320)
96G2648 (520)
96G3694 (320)
96G2648 (520)
96G3694 (320)
96G2648 (520)
Processor Jumper
50/75 MHz open 3-4, 5-6 open 3-4, 5-6 1-2 1-2 3-4, 5-6
60/90 MHz open 1-2, 5-6 open 1-2, 5-6 1-2 1-2 1-2, 5-6
(320 only)
66/100 MHz open 1-2, 3-4 open 1-2, 3-4 1-2 1-2 1-2, 3-4
(520 only)
66/133 MHz Not Supported 1-2 1-2, 3-4 1-2 2-3 1-2, 3-4

You can run the MYT planar to 120 MHz (60 MHz x 2.0) but AFAIK, that's the fastest you can go: based on my experience, if you set J43 to 66 MHz, then the system won't boot. You need the MDx or MZx planar to run at 66 MHz.

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.

Ardent Tool of Capitalism is maintained by Tomáš Slavotínek.
Last update: 08 May 2024 - Changelog | About | Legal & Contact