Commodore VIC-20 - Page 317

Appendix B: Memory Usage 303
TABU B-1: Memory Map (continued)
Hex
Decimal
Description
Address
Address
9121 37153
Port A output register keyboard row scan
9122 37154
Data direction register B
9123
37155
Data direction register A
9124 37156
Timer I, low-byte latch
9125 37157
Timer I, high-byte latch
9126
37158
Timer I, low-byte counter
9127 37159
Timer I, high-byte counter (timer I
is used
for the 60 time/second interrupt)
9128
37160
Timer
2, low-byte latch
9129
37161
Timer 2, high-byte latch
912A 37162
Shift register
912B
37163
Auxiliary control register
912C 37164 Peripheral control register
CAl Cassette read line (Bit 0)
CA2 Serial clock out (Bits 1-3)
. CBI Serial SRQ IN (Bit 4)
. CB2 Serial
data out (Bits 5-7)
912D
37165
Interrupt flag register
912E 37166
Interrupt enable register
912F 37167
Port A output register
9400-95FF 37888-38399
Location
of COLOR RAM with additional
RAM
at blk I
9600-97FF
38400-38911
Normal location
of COLOR RAM
9800-9BFF 38912-39935
I/O block 2
9COO-8FFF 39936-40959
I/O block 3
AOOO-BFFF 40960-49151
8K decoded block for expansion
ROM
COOO-DFFF 49152-57343
8K BASIC ROM
EOOO-FFFF 57344-65535
8K KERNAL ROM