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Vic 20 Memory Expansion

Available on Commodore Vic 20 computers. On the left side.

  1               TOP              22

+-------------------//----------------+

| =================//================ |

+-----------------//------------------+

  A              BOTTOM             Z

UNKNOWN (At the Computer)

UNKNOWN CONNECTOR at the Computer.

Pin Name Description
A GND Ground
B CA0 Address 0
C CA1 Address 1
D CA2 Address 2
E CA3 Address 3
F CA4 Address 4
H CA5 Address 5
J CA6 Address 6
K CA7 Address 7
L CA8 Address 8
M CA9 Address 9
N CA10 Address 10
P CA11 Address 11
R CA12 Address 12
S CA13 Address 13
T I/O 2 Decoded I/O block 2, starting at $9130
U I/O 3 Decoded I/O block 3, starting at $9140
V S02 Phase 2 System Clock
W /NMI Non maskable Interrupt
X /RESET 6502 Reset
Y n/c Not connected
Z GND Ground
1 GND Ground
2 CD0 Data 0
3 CD1 Data 1
4 CD2 Data 2
5 CD3 Data 3
6 CD4 Data 4
7 CD5 Data 5
8 CD6 Data 6
9 CD7 Data 7
10 /BLK 1 BLK 1 (Memory location $2000 - $3fff)
11 /BLK 2 BLK 2 (Memory location $4000 - $5fff)
12 /BLK 3 BLK 3 (Memory location $6000 - $7fff)
13 /BLK 5 BLK 5 (Memory location $a000 - $bfff)
14 RAM 1 RAM 1 (Memory location $0400 - $07ff)
15 RAM 2 RAM 2 (Memory location $0800 - $0bff)
16 RAM 3 RAM 3 (Memory location $0c00 - $0fff)
17 V R/W Read/Write from Vic chip (1=R, 0=W)
18 C R/W Read/Write from CPU (1=R, 0=W)
19 /IRQ 6502 Interrupt Request
20 n/c Not connected
21 +5V +5 VDC
22 GND Ground
Contributor: Joakim Ögren
Sources: Inside your Vic 20 by Ward Shrake
Sources: "The Vic Revealed" by Nick Hampshire, 1982, Hayden Book Co, Inc.
Sources: "Vic20 Programmer's Reference Guide", 1992, Commodore Business, Machines, Inc. and Howard W. Sams & Company, Inc.
Please send any comments to Joakim Ögren.