Commodore PET User Manual page 430

Table G-1. PET Memory Map (Rev 2 ROMs) (Continued)
Memory Address
Sample Value
Decimal
515
516
517-518
519
520
521
522
523
524
525
526
527-536
537-538
539-540
541-546
547
548
549
550
551
552
553-577
578-587
588-597
598-607
608
609
610
Hexadecimal
0203
0204
0205-0206
0207
0208
0209
020A
020B
020C
0200
020E
020F-0218
0219-021A
0218-021C
0210-0222
0223
0224
0225
022e
0227
0228
0229-0241
0242-024B
024C-0255
0256-025F
0260
0261
0262
Decimal
255
o
37916
52
o
255
o
o
o
o
o
85
34048
o
13
255
1
11
32
o
o
5
5
255
o
o
1
Hexadecimal
FF
00
941C
34
00
FF
00
00
00
00
00
55
8500
0000
00
FF
01
OB
20
00
00
05
05
FF
00
00
01
Description
Matnx coordinate of key depressed at
current jiffy.
1-80~key
255~no key
Status of SHIFT key:
O~unshifted (up)
l-shifted (down)
Secondary jilfy clock
1
nterrupt driver flag for cassette * 1 ON
switch
Interrupt driver f1ag for cassette *2 ON
switch
Keyswitch PIA
Utility
1/0 flag:
O=LOAO
l=VERIFY
1/0 status byte
Number of characters in keyboard buffer
(0 to 9)
Flag to indicate reverse field on
(O=normal)
Keyboard buffer
110
bytes)
Hardware interrupt vector
6502 BRK instruction interrupt vector
Input routine storage (6 bytes)
542 021 E No. of characters on screen
line
Key image
Flag for cursor enable:
O=Enable
1=Oisable
Counter to flip cursor (20 to 1)
Copy of character at current cursor posi-
tion
Flag for cursor on/off:
O=cursor moved
1=blink started
Flag for tape write
High byte of screen line addresses
553-559=128 (Iines 1-7)
560-565=129 (Iines 8-13)
566-572=130 (Iines 14-20)
573-577=131 (Iines 21-251
Table of logical numbers of open files
Table 01 device numbers of open files
Table of secondary address modes 01
open files
Flag for input source:
O=keyboard buffer
1=screen memory
1/0 utility
Number of open files (index into tables)
417