Universal Desktop Box

Serial Y Cable Pinout
Cache Configuration
Spares Part Numbers
Troubleshooting

UDB Memory Configurations

The Universal Desktop Box uses industry standard 70ns JEDEC 72pin, 36bit SIMM modules. EDO, 32bit, and SIMM modules that emulate parity cannot be used as the Alpha processor utilizes a 72bit memory bus, consisting of 64 data bits plus 8 bits for ECC. SIMM modules must be installed in pairs of identical size and preferably from the same manufacturer

The 233MHz VX41 and VX42 variants of the UDB can accommodate special Digital 12MB SIMM modules, part number 54-23627-AA. These 12MB SIMM modules can only be used in slots 0 and 1 if they are to be fully recognized. Should they be used in slots 2 and 3 they will appear as only 8MB modules.

Due to the compact design of the Universal Desktop Box only SIMM modules that meet the JEDEC standard height of 1.5 inches may be used, most Digital 64 MB SIMM modules exceed this height and cannot be used.

Slot 0 Slot 1 Slot 2 Slot 3 Total
8 MB 8 MB Unused Unused 16MB
4 MB 4 MB 8 MB 8 MB 24 MB
12 MB 12 MB Unused Unused 24 MB
8 MB 8 MB 8 MB 8 MB 32 MB
16 MB 16 MB Unused Unused 32 MB
4 MB 4 MB 16 MB 16 MB 40 MB
12 MB 12 MB 8 MB 8 MB 40 MB
8 MB 8 MB 16 MB 16 MB 48 MB
12 MB 12 MB 16 MB 16 MB 56 MB
16 MB 16 MB 16 MB 16 MB 64 MB
32 MB 32 MB Unused Unused 64 MB
4 MB 4 MB 32 MB 32 MB 72 MB
8 MB 8 MB 32 MB 32 MB 80 MB
12 MB 12 MB 32 MB 32 MB 88 MB
16 MB 16 MB 32 MB 32 MB 96 MB
32 MB 32 MB 32 MB 32 MB 128 MB
64 MB 64 MB Unused Unused 128 MB
4 MB 4 MB 64 MB 64 MB 136 MB
8 MB 8 MB 64 MB 64 MB 144 MB
12 MB 12 MB 64 MB 64 MB 152 MB
16 MB 16 MB 64 MB 64 MB 160 MB
32 MB 32 MB 64 MB 64 MB 192 MB
64 MB 64 MB 64 MB 64 MB 256 MB