Table G-,.
PET
Memory
Map
(Rev
2 ROMs) (Continued)
Memory Address Semple Value
Decimal
Hexadecimal Decimal
Hexadecimal
Description
59457
E841
59458
E842
59459
E843
59460-59461
E844-E845
59462-59463
E846-E847
59464
E848
Perallel User Port
VIA
(59456-594711
01
00
FF
1E
00
FE
DE
C8
FF65
71
62AO
o
14
255
30
o
200
254
1/0
Port B
207= *2 cassette motor
on
223= *2 cassette motor
off
WAil
59456.23.23
waits
for
vertical
retrace of display
Bit 1
=PB1
(NFRD
on
IEEE
connector) out-
put
line
Bit
3=P83
(AlN
on
IEEE
connector) out-
put line
1/0
Port A
with
handshaking
Data Direction register for
1/0
Port B
Data Direction register for
1/0
Port A
For
each
bit
1
=output.
O=input
=0
ail input
=255
ail output
(Law. high arder)
Read
limer
1 Counter;
writeto
limer
1 Latch and (high byte)
initiate count
(Law. high arder)
Read
limer
1 Latch
Read
limer
2 Counter
low
byte and reset
interrupt;
write
ta
limer
2
low
byte
PEEK
(594641
Clock decrements every
microsecond
POKE
59464.n sets
SR
rate of shift from
high (n=O) ta
low
(n=255)
for music
from User Port.
Read
limer
2 Counter high byte;
write
ta
limer
2 high byte and reset interrupt.
PEEK
(594651
Clock decrements every
millisecond
Seriai
1/0
Shift register
(SR)
POKE
59466.15 or
51
or 85 ta generate
square wave output at
CB2
for playing
music fram User Port.
Auxiliary Control register.
=
16
Sets
SR
ta free-running mode for
music fram User Port.
=0
for proper operation
of
tape drive
Peripheral Control register
=
12
for graphies
on
shifted characters
= 14 for lower-case letters
on
shifted
characters
o 00 Interrupt
Flag
register
128 80 Interrupt Enable register
255
FF
1/0
Port A
without
handshaking
Page
241-256 Operating System (61440-65535)
File Control
25248
65381
113
E849
E848
E840
E84C
E84D
E84E
E84F
E84A
FOB6-FlOO
59456
59465
59468
59466
59469
59470
59471
59467
61622-61904
61905-63532
F1
D1-F82C
5t.'tin9
Addr.ss Function
61905 Fl
Dl
Get
a character
(without cursor)
61921
F1E1
Input a character
(wlth cursor)
423
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