Connector is 50 Pin Female Edge. The Bus got modified over the various versions of Apple IIs (Pin 19,35,39)
Motherboard Pin |
Name | Direction | Description |
---|---|---|---|
1 | /IOSEL | ![]() |
I/O Select. Active when page $Cn gets accessed. N.C. on slot 0 |
2 | A0 | ![]() |
Buffered address bus |
3 | A1 | ![]() |
Buffered address bus |
4 | A2 | ![]() |
Buffered address bus |
5 | A3 | ![]() |
Buffered address bus |
6 | A4 | ![]() |
Buffered address bus |
7 | A5 | ![]() |
Buffered address bus |
8 | A6 | ![]() |
Buffered address bus |
9 | A7 | ![]() |
Buffered address bus |
10 | A8 | ![]() |
Buffered address bus |
11 | A9 | ![]() |
Buffered address bus |
12 | A10 | ![]() |
Buffered address bus |
13 | A11 | ![]() |
Buffered address bus |
14 | A12 | ![]() |
Buffered address bus |
15 | A13 | ![]() |
Buffered address bus |
16 | A14 | ![]() |
Buffered address bus |
17 | A15 | ![]() |
Buffered address bus |
18 | R/W | ![]() |
Buffered Read/Write signal. |
19 | SYNC | ![]() |
Only Slot 7. SYNC from Video Generator. Not on Rev 0 Boards. Testpin on Slot 1 for //e |
20 | /IOSTRB | ![]() |
I/O Strobe. Active when $C800 and $CFFF gets accessed |
21 | /RDY | ![]() |
Activation during Phi1 will halt the CPU, with the address bus holding the last address |
22 | /DMA | ![]() |
Activation disables the 6502s address bus and halts the CPU |
23 | /INTOUT | ![]() |
Daisy-chained interrupt output to lower priority devices |
24 | /DMAOUT | ![]() |
Daisy-chained DMA output to lower priority devices |
25 | +5V | ![]() |
+5 Volt power supply. Max. 500mA for ALL peripheral boards |
26 | GND | ![]() |
System electrical ground |
27 | /DMAIN | ![]() |
Daisy-chained DMA input from higher priority devices |
28 | /INTIN | ![]() |
Daisy-chained interrupt input from higher priority devices |
29 | /NMI | ![]() |
Non-Maskable Interrupt. Monitor ROM starts interrupt handling routine at location $3FB |
30 | /IRQ | ![]() |
Interrupt ReQuest. Monitor starts the routine pointed to by $3FE/F |
31 | /RES | ![]() |
RESet |
32 | /INH | ![]() |
INHibits the on board ROMs ($D000-$FFFF) |
33 | -12V | ![]() |
-12 Volt power supply. Max. 200mA for ALL peripheral boards |
34 | -5V | ![]() |
-5 Volt power supply. Max. 200mA for ALL peripheral boards |
35 | COLORREF | ![]() |
Only Slot 7. 3.5 MHz Video COLOR REF. Not on Rev 0 Boards. Testpin on Slot 1 for //e. M2B0 on A2gs |
36 | 7M | ![]() |
7Mhz clock |
37 | Q3 | ![]() |
2Mhz asymetrical clock |
38 | PHI1 | ![]() |
1 MHz phase 1 clock |
39 | Various | ![]() |
USER1 on A2: Disable adressdecode. 65C02 SYNC on A2e. M2SEL on A2gs |
40 | PHI0 | ![]() |
1 MHz phase 0 clock (Inverted PHI1) |
41 | /DEVSEL | ![]() |
DEVice SELect. Active when $C0nX gets accessed; n - Slot#+8 |
42 | D7 | ![]() |
Buffered bi-directional data bus |
43 | D6 | ![]() |
Buffered bi-directional data bus |
44 | D5 | ![]() |
Buffered bi-directional data bus |
45 | D4 | ![]() |
Buffered bi-directional data bus |
46 | D3 | ![]() |
Buffered bi-directional data bus |
47 | D2 | ![]() |
Buffered bi-directional data bus |
48 | D1 | ![]() |
Buffered bi-directional data bus |
49 | D0 | ![]() |
Buffered bi-directional data bus |
50 | +12V | -?- | +12 Volt power supply. Max. 250mA for ALL peripheral boards |