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Commodore_Free_Issue_27_2009_Commodore_Computer_Club.d64
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vic20 memory
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2023-02-26
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Commodore VIC-20
Memory Blocks Illustrated
Leif Bloomquist,
leif@schemafactor.com
Table 1
+-----+----+---------+-------+
: Dec : Hex:Block# : Usage :
+-----+----+---------+-------+
:57344:E000:Block7 ! :KERNAL!:
------+----+---------+-------+
:49152:C000:Block6 ! :BASIC !:
+-----+----+---------+-------+
:40960:A000:Block5 " :(1)(2)":
+-----+----+---------+-------+
:32768:8000:Block4 : ->Table2
+-----+----+---------+-------+
:24576:6000:Block3 " : ":
+-----+----+---------+-------+
:16384:4000:Block2 " : ":
+-----+----+---------+-------+
:8192 :2000:Block1 " : ":
+-----+----+---------+-------+
:0 :0000:Block0 : ->Table3
+-----+----+---------+-------+
->TABLE 2
+-----+----+--------+--------+------+
:Dec :Hex :Unexpand:3KExpans:8K+Exn:
+-----+----+--------+--------+------+
:38912:9800: I/O $ : I/O $: I/O $:
+-----+----+--------+--------+------+
:38400:9600:Col Memc:Col Memc: - !:
+-----+----+--------+--------+------+
:37888:9400: - !: - !:SColMc:
+-----+----+--------+--------+------+
:36864:9000:VICVIA $:VICVIA $:VICVI$:
+-----+----+--------+--------+------+
:32768:8000:CharROM!:CharROM!:CharRO:
+-----+----+--------+--------+------+
->TABLE 3
+----+----+--------+--------+-------+
:7680:1E00:ScreMem%:ScreMem%:UsrBasi:
+----+----+--------+--------: :
:4608:1200:UsrBasic: :AREA(3):
+----+----: : :-------+
:4096:1000: AREA : :ScrMem :
+----+----+--------+--------+-------+
:1024:0400:3kAvail": ":3KAvai":
+----+----+--------+--------+-------+
: 0:0000:BASWMem$:BASWMem$:BASWMe$:
+----+----+--------+--------+-------+
BASIC starts at 4097
BASIC starts at 1025
BASIC starts at 4609
Legend:
! = ROM
* = RAM Built-in RAM
" = EXP Avail for external expansion
$ = I/O Used by Kernal, BASIC, or IO
% = SCRN RAM Used for screen display
BASWMem = Basic Working Memory
Notes:
(1) 8K Cartridges normally here
(Autostart).
(2) SYS64802 performs a soft-reset
which usually starts Autostart
cartridge mages.
(3) User BASIC Area continues beyond
$2000 with 8K+ Expansion.
Tips:
- To find where BASIC Area starts
: PEEK(43) + 256*PEEK(44)
- To find where BASIC Area ends
: PEEK(55) + 256*PEEK(56) (These can
also be changed to protect memory
from BASIC)
- To find which "page" screen memory
starts: PEEK(648)
30 = $1E, meaning $1E00 (Unexpanded
or 3K expanded VIC)
16 = $10, meaning $1000 (8K or more
expansion)
..END..