ZX-Spectrum +3's expansion I/O socket
U 27 26 25 24 23 22 21 8 7 6 5 4 3 2 1
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-. .-.
|^^^^^^^^^^^^^^^^^^^^^^^^^^^^ /////// ^^^^^^^^^^^^^^^|^^^^^^^^^^^^^^^^|
|____________________________ /////// _______________|________________|
`-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-' `-'
L 27 26 25 24 23 22 21 8 7 6 5 4 3 2 1
EXPANSION I/O socket
|
PIN
|
UPPER ROW (U)
|
LOWER ROW (L)
|
|
1
|
A15
|
A14
|
|
2
|
A13
|
A12
|
|
3
|
D7
|
+5V
|
|
4
|
ROM 1 OE
|
not used
|
|
5
|
D0
|
GND
|
|
6
|
D1
|
GND
|
|
7
|
D2
|
CK
|
|
8
|
D6
|
A0
|
|
9
|
D5
|
A1
|
|
10
|
D3
|
A2
|
|
11
|
D4
|
A3
|
|
12
|
INT
|
not used
|
|
13
|
NMI
|
GND
|
|
14
|
HALT
|
ROM 2 OE
|
|
15
|
MREQ
|
DISK RD
|
|
16
|
IORQ
|
DISK WR
|
|
17
|
RD
|
MOTOR ON
|
|
18
|
WR
|
BUSRQ
|
|
19
|
not used
|
RESET
|
|
20
|
WAIT
|
A7
|
|
21
|
+12V
|
A6
|
|
22
|
-12V
|
A5
|
|
23
|
M1
|
A4
|
|
24
|
RFSH
|
not used
|
|
25
|
A8
|
BUSACK
|
|
26
|
A10
|
A9
|
|
27
|
RESET
|
A11
|