Spectravideo SVI318/328 Expansion Bus

50 PIN MALE EDGE the computer.

Pin Name Dir Description
1 +5v --> Power, 300mA
2 /CNTRL2 <-- Game adapter control signal
3 +12v --> Power, 100mA
4 -12v --> Power, 50mA
5 /CNTRL1 <-- Game adapter control signal
6 /WAIT <-- Z80 WAIT
7 /RST <-- Z80 RST
8 CPU CLK --> Buffered 3.58MHz system clock
9 A15 --> Buffered Address bus
10 A14 --> "
11 A13 --> "
12 A12 --> "
13 A11 --> "
14 A10 --> "
15 A9 --> "
16 A8 --> "
17 A7 --> "
18 A6 --> "
19 A5 --> "
20 A4 --> "
21 A3 --> "
22 A2 --> "
23 A1 --> "
24 A0 --> "
25 /RFSH --> RAM expansion refresh
26 /EXCSR <-- Video-CPU write select
27 /M1 --> Z80 M1
28 /EXCSW <-- CPU-Video write select
29 /WR --> Z80 WR
30 /MREQ --> Z80 MREQ
31 /IORQ --> Z80 IORQ
32 /RD --> Z80 RD
33 D0 I/O Buffered Data Bus
34 D1 I/O "
35 D2 I/O "
36 D3 I/O "
37 D4 I/O "
38 D5 I/O "
39 D6 I/O "
40 D7 I/O "
41 CSOUND <-- Audio input signal
42 /INT <-- Z80 INT
43 /RAMDIS <-- Disable user RAM
44 /ROMDIS <-- Disable basic ROM
45 /BK32 --> Enable bank 32 Memory (8000-ffff)
46 /BK31 --> Enable bank 31 Memory (0000-7FFF)
47 /BK22 --> Enable bank 22 Memory (8000-FFFF)
48 /BK21 --> Enable bank 21 Memory (0000-7FFF)
49 GND - System Ground
50 GND - System Ground

Source: [The Hardware Book]

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