Posted By
Litwr
on 2016-09-22
16:30:25
|  Re: What would I do differently in the Plus/4
z80. LD (HL),n uses 10 t-states and has 3 access to the memory, so we have 3.33 t-states not 4. These accesses to memory are irregular... LD HL,(address) uses even 16 t-states and 5 accesses to the memory.
BBC Micro uses RAM at 4 Mhz (see wiki). 2 Mhz for CPU and 2 Mhz for video. So DRAM for 4 Mhz was available at 1981. MSX was the exception, they use too slow RAM.
Maybe +4 requires a bit faster RAM for 3.5 MHz but the price couldn't differ much.
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