Motherboard Specifications

The motherboard is CHRP (Common Hardware Reference Platform) compliant. It's a preproduction IBM Long Trail clone, made by an Asian manufacturer. The board has a standard ATX form factor and should fit in any ATX compliant case. The full LongTrail specs can be downloaded from IBM's FTP site.

My board has the following specifications:

Main System Logic

Sockets and Connectors

Production boards (will) have slightly different specifications:

Motherboard Connectors and Jumper Settings


Label Type Function
JPS 2x10 (ATX holder type) connected to ATX power supply
JLPT 2x13 (pin 26 off) parallel port connector
JFDD 2x17 (pin 5 off) floppy connector
JHDD1 2x20 (pin 20 off) primary HDD connector
JHDD2 2x20 (pin 20 off) secondary HDD connector
JSCSI_1 2x25 Internal SCSI connector
J3D 1x20 (pin 7 key) (option) 3D sound card connector
JFAN1 1x4 (holder type) CPU fan connector
JCDROM 1x4 (holder type) CDROM connector
JMIC1 1x3 (holder type) power connector to PW6600 R00B board
JMIC2 1x4 (holder type) MIC left/right/gnd signals to PW6600 R00B board
JHEAD 1x5 (holder type) EARPHONE left/gnd/right signals to PW6600 R00B board
JMIDI 2x8 (pin 16 off) MIDI/GAME port connector
JSPKR 1x2 reserved
JFAX 1x4 reserved
JFAN2 1x4 reserved
JRST/JPWR/JHDI 1x2 * 3 (JPWR pin 2 off) reset/power/hdd connector connected to PWLT00G R00A
JPUSH2 1x2 2nd power on/off connector connected to PWLT00G R00A
JPUSH1 1x2 power on/off connector connected to power switch

Jumper Settings

Label Type Function
JPRMOD 2x2 CPU operation mode setting
603e 1-3 / 2-2 NO_DRTRY
604e 1-3 / 2-4 NO_DRTRY
604 1-1 / 2-4 FAST_L2
604 1-1 / 2-2 Normal (default)
JA2V 2x3 CPU 2nd voltage selection
2.53V 2-4 (default)
2.73V 4-6
2.85V 3-5
2.93V 1-3
JTAG and JLPD 2x3 and 2x4 2nd cache size setting
Cache type JL2PD JTAG
1-2 / 3-4 / 5-6 / 7-8
256PB OUT / IN / OUT / OUT 1-1 / 2-2 / 5-5
256+256PB IN / OUT / OUT / IN 1-3 / 2-4 / 5-5
512PB IN / OUT / OUT / OUT 1-2 / 3-4 / 5-5 (default)
512+512PB IN / IN / IN / IN 1-2 / 3-5 / 4-6
JCLK 2x3 CPU bus clock setting
Bus/PCI 1-2 / 3-4 / 5-6
50 / 25 IN / IN / OUT
55 / 27.5 OUT / OUT / OUT
60 / 30 OUT / IN / OUT
66 / 33 IN / OUT / OUT (default)
75 / 37.5 IN / IN / IN
JCFG0/1/2 1x3 * 3 CPU/bus clock ratio setting
2/1 2-3 1-2 2-3
5/2 2-3 1-2 1-2
3/1 1-2 2-3 2-3 (default)
4/1 1-2 2-3 1-2
7/2 1-2 1-2 1-2
J3DS1/J3DS2 1x2 * 2 3D sound card select
3D Sound Card J3DS1 J3DS2
None ON ON (default)
Installed OFF OFF
JP/W 1x3 Reserved

Warning: production boards have different jumpers for

Refer to the silk prints on the motherboard for information about these.

Memory requirements for the LongTrail

The LongTrail uses the VLSI VAS96011/12 `Golden Gate II' (GG2) PCI chipset. This 2 IC chipset contains a PowerPC CPU interface, and L2 cache, DRAM and PCI controllers. What kind of memory you can use is dependent on the memory controller in the GG2.


The Longtrail has 3 sockets for DIMMs (Dual In-line Memory Modules).

DIMMs with 168 pins can contain 1 or 2 banks of memory. Usually single sided DIMMs have 1 bank of memory, while double sided DIMMs have 2 banks of memory, but this is not always the case.

DIMMs provide a 64 bit wide path to the memory. With 8 bit wide ICs (e.g. 2Mx8 or 8Mx8) each bank on the DIMM contains 8 ICs. With smaller (e.g. 4Mx4) or wider (e.g. 4Mx16) ICs, you need more or less ICs to fill each bank on the DIMM.


The GG2 supports Fast Page Mode (FPM), Enhanced Data Out (EDO) and Burst EDO (BEDO) DRAM. You can have up to 768 MB of FPM, EDO or BEDO memory in 6 banks (i.e. 3 DIMM sockets).


Synchronous DRAM (SDRAM) is a higher performance and newer type of memory. Currently EDO RAM is being phased out by SDRAM, just like FPM was phased out by EDO before.

The GG2 supports up to 512 MB of SDRAM in 4 banks (i.e. 2 DIMM sockets). The GG2 supports SDRAM with 2 internal banks only. If you have SDRAM with 4 internal banks, you can use half the amount of memory only, or none at all if you have back luck!


Originally, all SDRAM had 2 internal banks. Do not confuse the internal SDRAM banks with the banks of a DIMM!

The internal SDRAM banks are used to implement on-chip memory interleaving and are the reason for the higher performance that can be achieved with SDRAM, compared to older memory technologies. Read more about SDRAM in this announcement from IBM from 1996.

Later SDRAM could have 2 or 4 internal banks (IBM and HP). To support this, an extra bank select line BA1 was added in addition to BA0. Since the GG2 is a design from 1996 or before, it makes sense to assume it holded pace with the memory technology from that moment. Hence the GG2 does not support the BA1 bank select line. The memory controller in the Motorola MPC106 `Grackle' chipset (used in the Apple PowerMac G3) does support SDRAM with 4 internal banks, starting with revision 4.0 of the MPC106. AFAIK all PC chipsets that support SDRAM do support SDRAM with both 2 or 4 internal banks.

Most 16 Mb SDRAM ICs have 2 internal banks. 64 Mb ICs are available from the major DRAM manufacturers with both 2 or 4 internal banks. Since this is a PC centered world, 64 Mb ICs with 4 internal banks are most popular.



Thus for the LongTrail, you need SDRAM DIMMs with ICs that have 2 internal banks. Most shops will not know what you're talking about. But if you insist and the shop has a sense for service and client relations, you should be able to get them. At least 64 MB SDRAM DIMMs with 2 internal banks can be bought (but it took me months). Higher capacities are extremely difficult to find. Companies specialized in workstation memory may have them, but they can be an order of magnitude more expensive than commodity PC shops.

Things will only get worse, because of the fastly evolving memory technology and computer world. Older technology is being phased out, and you can't expect to keep on buying memory for such old machines (sigh).

You can verify whether the type of your memory at the website of the memory manufacturer. Useful links:

If you have no idea who's the manufacturer, just feed the markings on the chips to Alta Vista.

Memory types I have used

During the history of my LongTrail, I succesfully used the following types of memory: The following failed: I'm aware of at least one conflict between a specific Open Firmware version and a specific 32 MB SDRAM DIMM: the machine didn't boot up at all. We tried two different LongTrail hardware revisions, but the motherboard didn't matter. The same DIMM worked fine with a different Open Firmware version, and the same Open Firmware PROM worked fine with other DIMMs. Sigh...
Disclaimer: I gathered this information over the last year while desperately looking for +64 MB DIMMs that work in my LongTrail. Not everything may be 100% correct.

This page is maintained by Geert Uytterhoeven.
$Date: 2006-01-25 21:24:49 $