26 Jan
2008
26 Jan
'08
6:15 a.m.
From: dkelvey at hotmail.com
To: cctalk at classiccmp.org
Date: Thu, 24 Jan 2008 08:51:42 -0800
Subject: RE: div by 10 on Z80
Date: Thu, 24 Jan 2008 01:09:31 -0500
From: rtellason at verizon.net
To: cctalk at classiccmp.org
Subject: Re: div by 10 on Z80
---snip---
I went back and looked at the schematics. It uses the BUSREQ lines
on the Z80. The circuit is a little too complicated to describe. There
is some gating and because the RAMs on the controller ar DRAMs, things
are a little more complicated than would be needed for statics.
I still believe the fact that the Z80 is suppose to be running faster
than the 8080, it should responded with a BUSAK that handshakes
to the S100 by the PRDY line.
Dwight
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On Thursday 24 January 2008 00:30, dwight elvey
wrote:>> There are two windows in the Z80 memory that are double accessed
by both the S100 side and the Z80 side. One window at 1000H for
buffering while the other is only 16 bytes used for command, parameters
and status.
I'd be real interested in more details about how they do that.