Rather than using z80 I/o space) , would memory-mapping the VDC(eg 9x18 variant) itself (ie its control registers etc) allow some faster z80 instructions to be used (eg to send a block of consecutive vdu bytes).?...In the 1980s if you did want your Z80A system to run the processor at 4 MHz with no pausing for a video system to share the bus, the answer at the time was to use a video display processor that had its own private video DRAM (16 K bytes). But this has the disadvantage that data transfer from the processor to the video DRAM was via an I/O port. Hence it's slower than if the video DRAM was memory mapped....
Statistics: Posted by B3_B3_B3 — Sun Jan 12, 2025 10:58 pm