# MSX Expansion

    49 47 45   5 3 1
    +---------//-----+
    | H H H  //H H H |
    | ======//====== |
    | H H H//  H H H |
    +-----//---------+
     50 48 46  6 4 2

(at the Computer)

50 PIN ?? at the Computer.

Pin | Name | Dir | Description
--- | --- | --- | ---
1 | /CS1 |  | Memory Read in addresses 4000-7FFF
2 | /CS2 |  | Memory Read in addresses 8000-BFFF
3 | /CS12 |  | Memory Read in addresses 4000-BFFF
4 | /SLTSL |  | Low when Slot 2 (cartridge slot) is selected
5 | n/c | - | Not connected.
6 | /RFSH |  | Refresh signal from CPU
7 | /WAIT |  | OC, Tells CPU to wait. Refresh signal is not maintained
8 | /INT |  | OC, Requests a interrupt to CPU (call to addr 38h)
9 | /M1 |  | CPU fetches first part of instruction from memory.
10 | /BUSDIR |  | NC, was used to control the data direction.
11 | /IORQ |  | I/O request signal. (Address=Port)
12 | /MREQ |  | Memory request signal. (Address=Address)
13 | /WR |  | Write signal (strobe)
14 | /RD |  | Read signal (strobe)
15 | /RESET |  | Reset
16 | n/c | - | Not connected.
17 | A0 |  | Address 0
18 | A1 |  | Address 1
19 | A2 |  | Address 2
20 | A3 |  | Address 3
21 | A4 |  | Address 4
22 | A5 |  | Address 5
23 | A6 |  | Address 6
24 | A7 |  | Address 7
25 | A8 |  | Address 8
26 | A9 |  | Address 9
27 | A10 |  | Address 10
28 | A11 |  | Address 11
29 | A12 |  | Address 12
30 | A13 |  | Address 13
31 | A14 |  | Address 14
32 | A15 |  | Address 15
33 | D0 |  | Data 0
34 | D1 |  | Data 1
35 | D2 |  | Data 2
36 | D3 |  | Data 3
37 | D4 |  | Data 4
38 | D5 |  | Data 5
39 | D6 |  | Data 6
40 | D7 |  | Data 7
41 | GND |  | Ground
42 | CLOCK |  | CPU clock, 3.579 MHz
43 | GND |  | Ground
44 | SW1 | - | NC, Insert/remove detection for protection
45 | +5V |  | +5 VDC (300mA max /slot)
46 | SW2 | - | NC, Insert/remove detection for protection
47 | +5V |  | +5 VDC (300mA max /slot)
48 | +12V |  | +12 VDC (50mA max /slot)
49 | SOUNDIN |  | Sound input (-5dBm)
50 | -12V |  | -12 VDC (50mA max /slot)

Note: Direction is Computer relative Peripheral.

Contributor: Joakim Ögren

Source:
Mayer's SV738 X'press I/O map

Copyright © The Hardware Book Team 1996-2001.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2001-06-08