[Coco] VCC possible bug in 6309 & 6809 emulation and general Wally news!

Robert Gault robert.gault at att.net
Mon Jun 11 09:41:55 EDT 2018


Your observations of non-standard operations from the pdf are very interesting. The exchanges 
between 8-bit and 16-bit registers and a Zero register are definitely not in the Hitachi Data book. 
This information is also not mentioned in one of the better books on programming: "6809 Assembly 
Language Programming" by Lance A. Leventhal, McGraw-Hill.

Nevertheless, I did run a test on my Coco3 which has a 6309 chip and non-equal register transfers 
work and there does seem to be a Zero register.

A note to anyone using Tandy's EDTASM or my EDTASM6309, you can only perform these operations by 
manually programming them with FCB statements. The assemblers will reject code such as:
TFR X,A or TFR Z,A . You can, however, enter ex.   FCB $1F,$C8    which makes the 6309 clear regA. 
$1F=TFR and %1100xxxx or %1101xxxx = from Z and %xxxx1000 = to regA.


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