[Coco] assembly language question.
devries.bob at gmail.com
Wed Feb 3 23:16:36 EST 2010
the orientation of the < is importnat of course, and will determine the 8 or
16 bit operation.
To compare the X register with memory, it would need to read:
Regards, Bob Devries
Besides a mathematical inclination, an exceptionally good mastery of one's
native tongue is the most vital asset of a competent programmer.
Edsger W.Dijkstra, 18 June 1975
----- Original Message -----
From: "Gene Heskett" <gene.heskett at verizon.net>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Thursday, February 04, 2010 2:59 PM
Subject: Re: [Coco] assembly language question.
> On Wednesday 03 February 2010, jdaggett at gate.net wrote:
>>The operation is always
>>R - M
>>where R is the register and M is either a second register or memory. CCR
>> set according to the results and addressing mode.
>>In your case the MPU would take $02FA and subtract $000A. The subtraction
>> instruction will affect the N, Z, V or C bits. The BLO instruction tests
>> the C bit and will issue a branch if and only if the CBIT = 1. In this
>> case there is no borrow so the CBIT will be zero and no branch taken.
> Confirming my aged wet ram's memory of it. Thanks James.
> Cheers, Gene
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