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Subject: Re: 6809 - a 8/16-bit hybrid with sex

Author: Gerd Isenberg

Date: 13:04:55 09/27/05

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On September 27, 2005 at 00:22:55, Carey wrote:

>On September 26, 2005 at 16:58:09, Gerd Isenberg wrote:
>
>>On September 26, 2005 at 13:57:23, Gerd Isenberg wrote:
>>
>>>>
>>>>The Matchbox CPU (zelfbouw 6809), a 16-bit one.
>
>>Really a fascinating CPU, a 8/16 bit hybrid,
>>with sex, Sign extend B into A.
>
>Yup... The 6809 used to easly outperform 6502's running at twice the speed.
>
>The SEX instruction was always amusing to tell about.... But it was,
>unfortunately, a very boring instrunction.

Why is SEX boring ;-?
Doesn't it combine a lda and arithmetic shift right 8 instruction?
I guess because of the fixed register a,b association.

Btw. is the BIT-instruction similar to x86 bt- or to test-instruction?
6809 has tst-instruction as well, but no idea wehther it performs a temporary
and.

Gerd



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