Data-Gear DMA





8-bit DMA interface for Z80 based machines including the Sam Coupé.

Full details at


“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”

For those of us who don't read Czech,

For those of us who don’t read Czech, what can you actually do with this chip? Does it contend with the Z80B for memory bandwidth while it runs?

Have a look at:

Also as mentioned on

“Data Gear DMA Interface
Posted By: icabod, Friday, March 16, 2007 - 01:29 PM

One of the great things about the MB02+ disc system is/was the DMA. Using the device’s built-in Zilog DMA chip you could throw data around at very high rates, meaning some nice FX (such as Multitech and other lovely graphics effects) were possible. Over on the WOS forum Velesoft, the Czech hardware guru has mentioned the Data-Gear, an internal mod that provides the same DMA functionality as the MB02+, without needing an actual MB02+. Nice, huh? In fact, here’s an example of what you can achieve - the green area is the time spent doing DMA. Yep, entire screen scrolling in about half a frame.”

2t ?
goto page
page 185
does it make any sense to you
the last page of velesoft has 8 pixel long lines of colour in the border
he reckons this is 4tstate write ram to port
do you understand this diagram as it looks more like 2tstates
its probably not possible even with uncontentioned port and ram used
but 2tstates would be a 4 pixel line no? - unless you could add a latch to the ula that did it in less? like the serial pixel latch for the pixel ram area slow things down a bit though?
just think on sam with sam with sams clock?3pixels?
but not mode one ofcourse they might be a bit smaller still?

English Update

Velosoft has updated the page in English, quote from site added above.

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