Commodore Amiga - Page 300

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systems programner and should generally not be used by applications
programners. Systems software nonnally is configured to handle the
setting of particular Signals, no matter how the physical connections
may change. In other words, if you have a version of the system
software that matches the rev. level of the machine (nonnally a true
condition), when you ask that a particular bit be set, you don't care
which port that bit is connected to. Thus applications progranmers
should rely on system documentation rather than going directly to the
ports. Note also that in this, a multi-tasking operating system, many
different tasks may be conpeting for the use of the system resources.
Applications programmers should follow the established rules for
resource access in order to assure coupat1hl1ity of their software
with the system.
Address BFERFF data bits 7-0 (Al2*) (int2)
PA7 .. game port 1, pin 6 (fire button*)
PA6 .. game port 0, pin 6 (fire button*)
PAS •. ROY. disk ready'
PA4 .. TKO. disk track 00*
PA3 .. WPRO* write protect*
PAl •. CHNG' disk change'
PAl .. LED. led light (O=bright)
PAO . .fNL memory overlay bit
SP ••• KDAT keyboard data
CNT •• KCLK
PB7 .• P7
PB6 .. P6
PBS •• PS
PB4
.• P4
PB3 .. P3
PB2 •. P2
PBl. .Pl
PBO •. PO
PC ••• drdy*
F •••• ack·
data 7
data 6
data 5
data 4
data 3
data 2
data 1
data 0
Centronics parallel interface
data
centronics control
Address BEDRFE data bits 15-8 (Al3*) (int6)
PA7 •• com line D'lR*, driven output
PA6 •• com line RTS*, driven output
PAS •• com line carrier detect*
PM •• com line CTS*
PA3 •• com line DSR*
PAl •. SEL centronics control
PAl •. POUT paper out ---+
PAO •• BUSY busy ---+ I
I I
SP ••• BUSY COIIIDOdore -+ I
CNT •• POUT COIIIIIOdore ---+
PB7 •. MTR*
PB6 •• SEL3*
PBS •• SEL2*
PB4 .. SELl*
PB3
•. SELO*
PB2 •. SIDE*
PBl. .DIR
PBO •• STEP*
PC ••• not used
F •••• INDEX*
motor
select external 3rd drive
select external 2nd drive
select external 1st: drive
select internal drive
side select*
direction
step*
disk index*