[Coco] assembly language question.

[William Astle]

Arthur Flexser wrote:
> The example seems a bit unusual in that you're comparing a 16-bit quantity
> (the X register) with an 8-bit one (due to the use of the 'less than'
> sign).  I'm guessing that that would cause only the LSB of X ($FA) to be
> compared to <$000A (=$0A) with the outcome that the BLO no branch since $FA
> is greater than $0A by an unsigned comparison.

Not correct, actually. That's "direct page" addressing. That has no 
impact on the operand size. Only the address the operand is fetched from.

> 
> Art
> On Wed, Feb 3, 2010 at 9:10 PM, Gene Heskett <gene.heskett at verizon.net>wrote:
> 
>> Greets all;
>>
>> I've read through the moto programmers manual for the 6809 for the cmp
>> functions, and am still confused.  The cmp function is a subtract function
>> where the answer is thrown away, only affecting the CC flags so that a
>> following beq or blo will take the correct jump.  But somehow, it isn't
>> clear
>> which is subtracted from what.
>>
>> Given that regs.x contains $02FA, and that the integer memory location
>> referenced by LblName contains $000A, will the blo take, or be ignored
>> here?
>>
>>        cmpx  <LblName memory address in DP that holds the $000A above
>>        blo     somewhere else
>>
>> Thanks.
>>
>> --
>> Cheers, Gene
>> "There are four boxes to be used in defense of liberty:
>>  soap, ballot, jury, and ammo. Please use in that order."
>> -Ed Howdershelt (Author)
>>
>> <cesarb> Damn, every time I spawn, qf-client-x11 locks hard
>> <Zoid> Don't die?
>> <Knghtbrd> good incentive.
>>
>> --
>> Coco mailing list
>> Coco at maltedmedia.com
>> http://five.pairlist.net/mailman/listinfo/coco
>>
> 
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
> 


-- 
William Astle
lost at l-w.ca