woody@tybalt.caltech.edu (William Edward Woody) (03/02/88)
While tromping through the Macintosh II roms with my steel tipped boots on,
I noticed that when you do a _Status call (PBStatus() for all you Pascal
and C fans) to an open driver with csCode set to 1 in the ParamBlockRec,
then in the first 4 bytes of csParam you get back the DCtlEntry record
for that driver. It seems that the ROMS are intercepting the _Status
call and looks up the DCtlEntry record for the open driver if csCode is
1; the ROMS never call the device driver itself.
My question is this: Is this documented anywhere? I see no mention in
Inside Macintosh anywhere about this "undocumented feature." And are there
any other caviats of which are the ROMS which I should be aware about in this
vain?
- William Edward Woody
woody@tybalt.caltech.edu (Mac>][n&&/|\)&&(MacII>AT)
Disclamer: I haven't the foggiest idea what I'm talking about...