P12 - Rom Pin-3 Function; P13 - Ram Pin-30 Function; P14 - Extra Serial Ports - David Griffith P112 Assembly And Operation Manual

9.12 P12 — ROM Pin-3 Function
Pin Assigment
1 +5V
2 U4 pin 3
3 /Memory Write
Pin 1 is at the left when holding the board with the battery to the bottom-right.
This jumper connects Pin 3 of the ROM socket either to /MWR, or to Vdd.
For normal use, connect to /MWR.
9.13 P13 — RAM Pin-30 Function
Pin Assigment
1 +5V
2 U2 and U3 pin 30
3 A17
For 512kB RAM chips, this pin should connect to A17. For smaller parts,
connect to Vdd.
9.14 P14 — Extra Serial Ports
Pin Signal
1 TXA1
2 RXA0
3 RTS0
4 CTS0
5 RTSB = TEND1
6 DTRB
7 CTS1
8 TXA0
9 RXA1
10 DCD0
11 CTSB
12 DCDB
13 Vcc
14 TXDB
15 TRXCB
16 RXDB
17 RTXCB
18 SYNCB
19 GND
20 GND
44