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 |