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 6502"s 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 |
D0 |
 |
Buffered bi-directional data bus |
| 43 |
D1 |
 |
Buffered bi-directional data bus |
| 44 |
D2 |
 |
Buffered bi-directional data bus |
| 45 |
D3 |
 |
Buffered bi-directional data bus |
| 46 |
D4 |
 |
Buffered bi-directional data bus |
| 47 |
D5 |
 |
Buffered bi-directional data bus |
| 48 |
D6 |
 |
Buffered bi-directional data bus |
| 49 |
D7 |
 |
Buffered bi-directional data bus |
| 50 |
+12V |
-?- |
+12 Volt power supply. Max. 250mA for ALL peripheral boards |