The C64 Keyboard

The C64 reads the keyboard data from the memory map, as 8 rows of 8 columns.
Where there are two characters shown the second is the shifted character.
Characters that may cause trouble due to PS/2 keyboard incompatibilities are coloured red.
The row bits are selected by writing to the memory-mapped CIA1 port A at address 0xdc00.
The column data bits are read from the CIA1 port B at address 0xdc01.

Row   Data (read on port B at 0xDC01)
    7 6 5 4 3 2 1 0
0   down f5 f3 f1 f7 right ret del
1   sh.L E S Z   A W  
e s z 4 a w 3
2   X T F C   D R  
x t f c 6 d r 5
3   V U H B   G Y  
v u h b 8 g y 7
4   n   k m o j i  
N 0 K M O J L 9
5   , @ : . - L P +
l p
6   / uparrow = sh.R home ; * £
7   run/stop Qq C= sp 2 ctrl esc- 1

PS/2 Scan code to C64 Matrix conversion

PC
kbd		 --> PS/2
interface		 -scan-code-> FIFO -> C64 Keyboard
Matrix Encoder		 <-- 4-bit row addr
--> 8-bit row data		 C64
CIA1
chip
           
<-- <-control-codes-   <-- encoder <-- status for LEDs

C64 Keyboard connector pinout

Pin Port
bit		 CIA
pin		 Function  
1     GND GND
2     N.C. polarity mark
3     RESTORE This key pulls this pin low to cause an NMI
4     VCC +5V
5 PB3 13 row 3 joystick 1 right
6 PB6 16 row 6  
7 PB5 15 row 5  
8 PB4 14 row 4 joystick 1 fire
9 PB7 17 row 7  
10 PB2 12 row 2 joystick 1 left
11 PB1 11 row 1 joystick 1 down
12 PB0 10 row 0 joystick 1 up
13 PA0 2 column 0 joystick 2 up
14 PA6 8 column 6 "1" -> paddle set A
15 PA5 7 column 5  
16 PA4 6 column 4 joystick 2 fire
17 PA3 5 column 3 joystick 2 right
18 PA2 4 column 2 joystick 2 left
19 PA1 3 column 1 joystick 2 down
20 PA7 9 column 7 "1" -> paddle set B