The SB180, 9MHz
The 9MHz version of the SB180 was essentially the same as the 6MHz version. The processor was
, spec'ed at 8MHz but run at 9.216MHz.
The three 74157 DRAM address multiplexor chips were replaced with faster 74S158 chips.
The 12.288MHz processor crystal was replaced with a 18.432MHz crystal. The EPROM was
also changed, to provide the new Baud Rate Generator constants for 9.216MHz operation.
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