Commodore Amiga A500 Technical Reference Manual page 6

EXTERNAL SYSTEM I/O
RS232 and MIDI Port
13 12 11 10 9 8 7 6 5
25 24 23 22 21 20 19 18 17
PIN RS232
1 GND
2 TxD
3 RxD
4 RTS
5 CTS
6 DSR
7 GND
8 DCD
9 —
10 —
11 —
12 S.SD
13 S.CTS
14 S.TxD
15 TxC
16 S.RxD
17 RxC
18 —
S.RTS
19
20 DTR
21 SQD
22 RI
23 SS
24 TxC1
25 —
This section describes each I/O interface in detail, and some of the
tradeoffs made with respect to A1000 compatibility.
The Amiga 2000 and Amiga 500 have differences in the serial and
parallel ports from the Amiga 1000, the main difference being
changes in the sex of each port (changing the serial to female and
the parallel to male), which allows the new Amigas to use standard
interface cables.
The RS232 connector on the A500 and A2000 is form fit and
function identical to a Commodore PC-10/20 with a few
exceptions. This is the OPPOSITE sex connector from the
A1000. The connector is a shielded male DB25P connector. The
4 3 2 1
16 15 14
A1000 supplies various non-standard RS232 signals on the DB25
connector. These non-standard signals were removed wherever
possible. The RS232 connector is NOT physically compatible with
some MIDI interfaces but is compatible with the Amiga
Modem/1200 RS {model 1680). Below is a comparison chart
between the RS232 standard, a Hayes Smart-modem standard, the
A1000 RS232, and the new Amiga 500/2000 RS232 connector.
A500/
A1000 A2000 PC10
GND GND
TxD TxD
RxD RxD
RTS RTS
CTS CTS
DSR DSR
GND GND
DCD DCD
— + 12v
— - 12v
— AUDO
—
—
—
—
—
-5Vdc
—
AUDO
—
AUDI
—
EB
INT2* AUDI
—
—
DTR DTR
+ 5Vdc —
— RI
+ 12Vdc —
—
C2*
—
RESB*
HAYES® DESCRIPTION
GND GND
TxD TxD
RxD RxD
RTS —
CTS CTS
DSR DSR
GND GND
DCD DCD
+ 12v —
- 12v —
— —
— SI
— —
— —
— —
— —
— —
— —
— —
DTR DTR
— —
RI RI
— —
— —
— —
3
Frame ground
Transmit Data
Receive Data
Request to send
Clear to send
Data set ready
Signal ground
Carrier detect
+ 12 volt power
- 12 volt power
Audio output
Speed Indicate
- 5 volt power
Audio output
Audio input
Port clock 716KHz
Interrupt line/Audio input
Data terminal ready
+ 5 volt power
Ring indicator
+ 12 volt power
3.58MHz clock
Buffered system