MEK6800D2 restoration

Chris Elmquist chrise at pobox.com
Tue Nov 23 06:16:25 CST 2010


I'm pretty sure that you need to read the ACIA data register at some point
after determining that a character is available else you will not get
updated status for the next incoming character.


On Tuesday (11/23/2010 at 03:32PM +0100), Wim wrote:
>
> Exactly.  And I just figured that they all are framing errors. Here's my test
> program that should exit when it reads a byte that has no framing error:
>
> 	LDAA #%00010000 ; like in jbug (8bit, np, 2stop, no divide)
> 	STAA $8008 ; acia control reg
> READ	LDAA $8008 ; acia status reg
> 	ASRA
> 	BCC READ  ; branch unless data ready
        LDAB $8009		; maybe?  read the incoming byte, arm for next
>      	BITA #%00001000 ; check framing error
> 	BNE READ ; branch if framing error
>       SWI

Chris
-- 
Chris Elmquist




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