Re: A85: FA70-FBFF?

To: assembly-85@lists.ticalc.org
Subject: Re: A85: FA70-FBFF?
From: Jimmy Mårdell <mja@algonet.se>
Date: Tue, 26 Aug 1997 23:40:28 -0700
References: <872624544@cedarcity.net>
Reply-To: assembly-85@lists.ticalc.org

Richardlewis wrote:
> 
> What the heck is the data bus that is used in interrupt mode 2?  It is
> normally random, and can't be controlled by the processor, right?
> That is all I know about it.

The databus transfers memory from the RAM or the ROM (I think) to the
CPU.
When an interrupt occurs, an external unit should put a byte on the
databus
(ie, the databus is also connected to an external unit). Since there are
no
external units, the byte that happens to be at the databus at the time
the
interrupt occurs will be the one chosen - ie you have NO control over
it.

-- 
Jimmy Mårdell                   "We are the crown of creation
mailto:mja@algonet.se            we may do whatever we please
http://www.algonet.se/~mja       Fuck nature, man rules!"
IRC: Yarin                         Fuck Nature /Cat rapes dog

References:

Re: A85: FA70-FBFF?

From: richardlewis@cedarcity.net (Richardlewis)

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