Gemlight GMB-486UN, User Manual

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Hardware Configuration
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2.3.1 UPGRADING CACHE
The GMB-486UN mainboard is available with an optional 32KB, 64KB,
128KB, or 256KB cache memory on-board. User can upgrade cache memory
by installing additional SRAM (Static Random Access Memory) chips in
sockets U36-U39 and U42-U45.
The speed of the SRAM chips needed depends on the clock speed of the
microprocessor:
50MHz CPU requires 20ns (tag) and 20ns (data) SRAM chips for SRAM
interleaved.
50MHz CPU requires 20ns (tag) and 25ns (data) SRAM chips for SRAM not
interleaved.
33MHz CPU requires 25ns (tag) and 25ns (data) SRAM chips.
25MHz CPU requires 35ns (tag) and 35ns (data) SRAM chips.
2.3.2 CACHE SIZE AND MEMORY LOCATIONS
The table below describes the chip capacity and socket location required for
each cache size configuration. User can use 8K x 8-bit or 32K x 8-bit SRAM
chips in banks 0 and 1, and in the Tag RAM sockets. Please note that, do not
combine different chip capacities in banks 0 and 1.
BANK 0 BANK 1 TAG
RAM
Cache
Size
U36 U37 U38 U39 U42 U43 U44 U45 U34
32K
8Kx8 8Kx8 8Kx8 8Kx8 NONE NONE NONE NONE 8Kx8
64K
8Kx8 8Kx8 8Kx8 8Kx8 8Kx8 8Kx8 8Kx8 8Kx8 8Kx8
128K 32Kx8 32Kx8 32Kx8 32Kx8 NONE NONE NONE NONE 8Kx8
256K 32Kx8 32Kx8 32Kx8 32Kx8 32Kx8 32Kx8 32Kx8 32Kx8 32Kx8
Table 2: Cache Size Configuration