[Coco] 6309 Division instructions

[jdaggett at gate.net]

Tim

Thanks for that. Then the document with Portal09 is in error also. 

Hear that Roger?????

If indeed it is a 16x8 and with a 8 bit signed quotient and 8 bit 
modulo then it is really a worthless instruction. Unless A very large 
integer divided by a small enough interger is going to overflow 
immediately. A difference of 128 and the results are uselless. 

1024/3 is a worthless division. The added time to create a 
preprocessor to determine if the dividend is significantly larger than 
the divisor along with any scaling will be as slow if not slower than a 
software divider. 

james

On 2 Aug 2005 at 13:52, tim lindner wrote:

To:             	coco at maltedmedia.com (CoCoList for Color 
Computer Enthusiasts)
Subject:        	Re: [Coco] 6309 Division instructions
From:           	tlindner at ix.netcom.com (tim lindner)
Date sent:      	Tue, 2 Aug 2005 13:52:28 -0700
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> <jdaggett at gate.net> wrote:
> 
> > "The  DIVD  (16  bit by 8 bit) instruction does a signed divide of
> > the contents of the D register with a value from memory (or in 
> > direct  mode). The signed  result  is  stored  with  the  quotient 
> > in  W and the modulo (remainder) in D."
> 
> Error!
> 
> It should read:
> 
> "The  DIVD  (16  bit by 8 bit) instruction does a signed divide of the
> contents of the D register with a value from memory (or in  direct 
> mode). The signed  result  is  stored  with  the  quotient  in B and
> the modulo (remainder) in A."
> 
> -- 
> tim lindner
> tlindner at ix.netcom.com                                   Bright
> 
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