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16

It has been already done for ZX spectrum. see Velesoft: DATA-GEAR It has DIL40 socket compatible pins at the bottom and it replaces Z80 (so the bus is as short as possible). According to that site The bandwidth is around: ZX128+ is 17.3 kB(17727 bytes) / frame = 865.6 kB(886350 bytes) / second The higher bandwidth allows: fast scrolls MultiTech ...


15

I've been thinking about something like this myself, recently. I wasn't planning on using a Z8410, though, but an Intel 8257-5. This has a number of advantages: It has 4 controller channels rather than 2 It was actually a cheaper chip than the Zilog chips The interfacing to the Z80 wouldn't be quite as easy, but fundamentally the Z80 and the Intel 8085 ...


9

Pushing large chunks of bytes around is actually a task a DMA chip is very good at. The point is: Pushing partial bytes around is a task a DMA chip doesn't help sooo much, there is a lot of the job still left to the CPU. A DMA chip is not capable of shifting the bits in a byte, which was one of the main operations when handling retro computers sprite ...


8

each DMA transfer must be programed so you need to set some I/O registers of the DMA chip like: BYTE DMA mode WORD source address WORD destination address WORD block size These are usually send by 8bit I/O requiring at least 1 instruction per 8 bit value but usually more depending on the DMA chip interconnection to computer and interface. Now if the ...


7

Is it possible that you're using the here the term 'blit' as in Bit-Blit? If yes, than it's inaproptiate, as your examples are only about moving (byte) data. Moving is just one function of a bit blit engine. Beside logical operations, it also includes the handling od rectangular areas in a display wich are not (always) a consecutive series of memory cells (...


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