# C16/C116/+4 Expansion Bus

Availble on Commodore C16, C116 and +4 computers.

(At the Computer)

50 PIN FEMALE EDGE (2 mm pitch) at the Computer.

Pin | Name | Description
--- | --- | ---
1 | GND | Ground
2 | +5V | +5 VDC
3 | +5V | +5 VDC
4 | /IRQ | Interrupt
5 | R/W | Read/Write (1=Read, 0=Write)
6 | C1HIGH | External Cartridge Chip Selects C1 High
7 | C2LOW | External Cartridge Chip Selects C2 Low (reserved)
8 | C2HIGH | External Cartridge Chip Selects C2 High (reserved)
9 | /CS1 | Chip Select Line 1
10 | /CS0 | Chip Select Line 0
11 | /CAS | Column Address Strobe
12 | MUX | DRAM address multiplex control signal
13 | BA | Bus Availble (Low=DMA)
14 | D7 | Data 7
15 | D6 | Data 6
16 | D5 | Data 5
17 | D4 | Data 4
18 | D3 | Data 3
19 | D2 | Data 2
20 | D1 | Data 1
21 | D0 | Data 0
22 | AEC | Address Enable Code
23 | EAI | External Audio In
24 | PHI 2 | Artificial Phi 2 signal
25 | GND | Ground
A | GND | Ground
B | C1LOW | External Cartridge Chip Selects C1 Low
C | /RESET | Reset
D | /RAS | Row Address Strobe
E | PHI 0 | Artificial Phi 0 Signal
F | A15 | Address 15
H | A14 | Address 14
J | A13 | Address 13
K | A12 | Address 12
L | A11 | Address 11
M | A10 | Address 10
N | A9 | Address 9
P | A8 | Address 8
R | A7 | Address 7
S | A6 | Address 6
T | A5 | Address 5
U | A4 | Address 4
V | A3 | Address 3
W | A2 | Address 2
X | A1 | Address 1
Y | A0 | Address 0
Z | n/c | Not connected
AA | n/c | Not connected
BB | n/c | Not connected
CC | GND | Ground

PHI 2: Address valid on the rising edge, data valid on the falling edge