[BBC-Micro] Reversing the Tube ULA (destructively)

David Harper dl.harper at btopenworld.com
Tue Oct 26 08:03:58 BST 2010


>> and I seem to remember him saying that it didn't do DMA I think,
>
> The Tube does DMA!?

The 80186 does DMA and uses the Tube to do it in the Master512. It does 
this, however, simply by using the normal Tube data transfer facilities, but 
the DRQ line from the Tube chip is connected to DRQ0 on the processor, 
rather than NMI as it is for some other processors. So the Tube chip does 
not require any extra facilities.

David Harper 




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