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:
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 ...
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 ...
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 ...
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 (...