Re: Apple II+ Mystery Card

[dempson@swell.actrix.gen.nz (David Empson)]

In article <CBtLBI.GMv@rainbow.cse.nau.edu> jwa@sunset.cse.nau.edu (James W Abendschan) writes:
>
> I don't know if you've tried this already, but have you checked the
> ID bytes?  Apple cards are supposed to (!) have a certain signature
> byte which tells you what the cards' function is.
> 
> do this:
> 
> ]CALL-151
> *C40C

This byte is only an "ID byte" in a card which obeys the Pascal 1.1
I/O card protocol.  Such cards can be identified by

$Cn05 = $38
$Cn07 = $18
$Cn0B = $01

Only if these three bytes match will $Cn0C be an ID byte (as you
described).

This protocol is used for serial cards, parallel cards, mouse cards,
etc.  It doesn't apply to disk drive interface cards (including SCSI
cards) which have their own ID bytes:

$Cn01 = $20
$Cn03 = $00
$Cn05 = $03

$Cn07 = $3C for older disk interface cards
$Cn07 = $00 for SmartPort devices

There are other "standard" ID bytes (e.g. a ThunderClock, which
doesn't obey the Pascal 1.1 standard and isn't a disk drive).
-- 
David Empson                                                               
dempson@swell.actrix.gen.nz                                                
Snail mail: P.O. Box 27-103, Wellington, New Zealand