8-bit DMA interface for Z80 based machines including the Sam Coupé.
Full details at http://velesoft.speccy.cz/data-gear.htm
“DATA-GEAR is DMA interface for 8-bit computers with Z80CPU. DATA-GEAR is connected to socket for Z80CPU, there’s no need any hardware modifications in your computer. DMA chip use direct access to memory or port. Transfer of linear data block (max. 64kB) memory to memory / memory to port / port to memory / port to port. For computers with max. CPU speed 4MHz is used Z80DMA chip, but for faster computers (SAM COUPE=6MHz, ZS SCORPION TURBO=7MHz …) is need use DMA chip at 6-8MHz. DMA chip is programmed via port 11(#0B) = MB02 compatible. On board is extra switch for change programming port to 107(#6B).
Max. speed of data transfer on ZX128+ is 17.3 kB(17727 bytes) / frame = 865.6 kB(886350 bytes) / second”