C128 Expansion Bus

From HwB

Available at the Commodore C128.



44 PIN FEMALE EDGE at the computer.

Pin Name Description
1 GND System Ground
2 +5V System Vcc
3 +5V System Vcc
4 /IRQ Interrupt request
5 R/W System Read/Write Signal
6 DClock 8.18MHz Video Dot Clock
7 I/O1 I/O Chip select $de00-deff
8 /GAME Sensed for memory map configuration
9 /EXROM Sensed for memory map configuration
10 I/O2 I/O Chip select $df00-dfff
11 /ROML External ROM select $8000-Bfff
12 BA Bus available output
13 /DMA Direct memory access input
14 D7 Data bit 7
15 D6 Data bit 6
16 D5 Data bit 5
17 D4 Data bit 4
18 D3 Data bit 3
19 D2 Data bit 2
20 D1 Data bit 1
21 D0 Data bit 0
22 GND System Ground
A GND System Ground
B /ROMH External ROM Select $c000-ffff
C /RESET System Reset Signal
D /NMI Non-Maskable Interrupt
E 1MHz System 1MHz clock
F TA15 Translated address bit 15
H TA14 Translated address bit 14
J TA13 Translated address bit 13
K TA12 Translated address bit 12
L TA11 Translated address bit 11
M TA10 Translated address bit 10
N TA9 Translated address bit 9
P TA8 Translated address bit 8
R SA7 Shared address bit 7
S SA6 Shared address bit 6
T SA5 Shared address bit 5
U SA4 Shared address bit 4
V SA3 Shared address bit 3
W SA2 Shared address bit 2
X SA1 Shared address bit 1
Y SA0 Shared address bit 0
Z GND System Ground



  • Commodore 128 Programmers reference guide