Re: Question about parallel card.

[nparker@inferno.uoregon.edu (Neil Parker)]

In article <1998031821103001.QAA04706@ladder03.news.aol.com>,
BabarStCyr <babarstcyr@aol.com> wrote:
>Hi
>
>Are old parallel cards able to send AND receive datas?
>In others words can I do a LDA $CXXX to GET a byte?
>Are they any "standard" programming address for this type of cards?

I recently saw the manual for the Apple Parallel Interface Card (the newer
version, that has both Apple and Centronics modes), and it seems to indicate
that the card can receive data.  I don't actually have a card to test it
with, alas.

But in general, the answer is "No"...most Apple II parallel cards are
send-only.


The "standard" I/O locations, such as they are ("n" = slot number):

     Signature bytes:  $Cn05 = $48
                       $Cn07 = $48

     Output port: $C080,X (X = slot*16)
     Status bit: $CnC1 (high bit = 0 if printer ready to receive data)

For example,

; Printer init routine
     LDA PSLOT       ;Get printer slot
     ORA #$C0
     STA OUT+2       ;Patch output routine
     ASL
     ASL
     ASL
     ASL
     TAX             ;Slot*16 into X
     RTS
;
; Printer output routine (char in A, slot*16 in X)
OUT  BIT $C0C1       ;(Patched by init routine)
     BMI OUT         ;Loop if not ready
     STA $C080,X     ;Send it
     RTS

               - Neil Parker
-- 
Neil Parker, nparker@inferno.uoregon.edu, nparker@axis.llx.com,
http://axis.llx.com/~nparker/     (Note new addresses and home page!)

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