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Re: ECB-DMA [message #8699 is a reply to message #8695] Mon, 21 June 2021 07:31 Go to previous messageGo to previous message
b1ackmai1er is currently offline  b1ackmai1er
Messages: 396
Registered: November 2017
Senior Member
Hi Andrew,

Interrupts are currently not being used for memory/memory copy so there is no activity on IEI-IEO.

However, interrupts can be used as part of memory/memory copy by programming a counter to generate a Pulse/Interrupt signal or generate a pulse / interrupt at end of transfer.

SW2 facilitates connecting CPU BUSAK line to the BAI input and consequently to the BAO ouput. In a single board system the BAI/BAO bud line does not really appear to be needed (IMO)

In a multi board DMA system SW2 would connect configured as above on the first board connect to BUSAK but other boards connect to BAI, so this is where the daisy chain and mainboard links come into play.

Still trying to ger my head around it.

Just the normal Z80 data, address and control signals are used. I can see that using flying lead for dma daisy chain signals would be a reasonable compromise if mainboard lines were scarce.

It's pretty clever, I am surprised they got this right first time. Would be nice if it was multichannel Smile

Still so much to learn.
 
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