Subject: Re: My problems with merged memory
To: Niklas Hallqvist <>
From: Gregory Kritsch <>
List: amiga-dev
Date: 03/07/1994 11:37:18
> >>>>> "Niklas" == Niklas Hallqvist <> writes:
> Niklas> I have tested the board both with and without the DTACK jumper
> I tried to decode it last night, and have now an idea of what it is
> used for.  DaTa ACKnowledge is driven low as long as the requested data
> is invalid, or if it were the opposite, in order to make slow memory
> (or slow memory-mapped registers) safely deliver values to the CPU.
> Is this correct?  I don't think the 16bit mem is to blame in this case

NOTE: I only have access to Zorro I specs, but I don't imagine the A590
would work with my A1000 if this stuff had changed...

The docs I have suggest that DTACK* is generated by the motherboard for you,
unless you assert the XRDY* pin (#18), in which case DTACK* will not be
asserted until you negate XRDY*.

> Niklas

Hope this helps (and if the information HAS changed for Zorro II, would
someone please let me know).