Expansion bus slots
This page was last modified 11:08, 16 January 2020 by Rderooy. Based on work by Mars2000you and Wild Penguin and others.



Several expansion bus connectors exist on MSX. These type of connectors were especially prevalent on early MSX1 models. The MSX standard does not specify the shape or pin-out of these connectors. The most common type is the 50-pin IDC connector (standard 2.54mm pitch) with one or two polarizing key. Pins are generally more or less the same as a cartridge slot.

Very few, if any, devices exist to connect to most of these connectors. But they can often be modified to accept standard MSX cartridges. An example of such a conversion from Expansion bus to MSX Cartridge slot can be found here.

MSX models

that use a 50-pin IDC connector with one polarizing key

Expansion Bus with one polarizing key.jpg
50-Pin IDC.jpg
System Pin-out
AVT FC-200
Fenner SPC-800
Frael Bruc 100 rev.1
Goldstar FC-80, FC-80U, FC-200, GFC-1080, GFC-1080A
Gradiente Expert GPC-1, Expert XP-800
Mini IQ-3000 (OCM)
Toshiba HX-10 series Normal
Samsung SPC-800 Unknown
Spectravideo SVI-728 Normal
Vestel FC-200
Yeno DPC-64

that use a 50-pin IDC connector with two polarizing keys

Expansion Bus with two polarizing keys.jpg

The corresponding female connector for this type is impossible to find. As such you have two options, either modify the Expansion Bus port on the MSX to accept a single polarizing key IDC connector, or remove the polarizing key on the female IDC connector. The later is easier and avoids modifying the MSX, but it has the risk of allowing the IDC connector to be inserted the wrong way around.

System Pin-out
AVT DPC-200, CPC-300 Swapped
Bawareth Perfect MSX1, Perfect MSX2 Swapped
CE-TEC MPC-80 Swapped
Daewoo CPC-88, CPC-200, CPC-300, CPC-300E, CPC-330K, CPC-400, CPC-400S, DPC-100, DPC-180, DPC-200 Swapped
Dynadata DPC-200 Swapped
Fenner DPC-200 Swapped
In Tensai DPC-200CD Swapped
Mitsubishi ML-G10 Unknown
Network DPC-200 Swapped
Olympia DPC-200, PHC-2, PHC-28 Swapped
Sanyo MPC-6, MPC-10, MPC-10mkII, MPC-11, MPC-100, PHC-28S, PHC-30 Normal
Sony HB-55, HB-75 (Japanese models only) Unknown
Talent DPC-200, DPC-200A, DPS-201, DPC-300, TPC-310, TPP-311, TPS-312 Swapped
Wandy DPC-200, CPC-300 Swapped

Pinout of the 50-pin IDC connector

The below table lists the "Normal" Pin-out which corresponds to that of a regular MSX Cartridge port.

In case of a swapped pin-out the odd and even pins are swapped. For instance Pin 1 and 2 are swapped, and so are Pin 3 and 4, etc. This seems like it only effected Daewoo manufactured systems.

Pin Name Type Description
1 /CS1 O ROM addresses 4000-7FFF select signal
2 /CS2 O ROM addresses 8000-BFFF select signal
3 /CS12 O ROM addresses 4000-BFFF select signal (for 256k ROM)
4 /SLTSL O Slot select signal
5 RSV (N.C) Reserved signal line - use inhibited
6 /RFSH O Refresh cycle signal
7 /WAIT I CPU's WAIT request signal
8 /INT I Interrupt request signal to CPU
9 /M1 O Signal expressing CPU fetch cycle
10 /BUSDIR I This signal controls direction of external databus buffer Cartridges are selected and L level is
output from each cartridge at data transmission time
11 /IORQ O I/O request signal
12 /MERQ O Memory request signal
13 /WR O Write timing signal
14 /RD O Read timing signal
15 /RESET O System reset signal
16 RSV(N.C) Reserved signal line - use inhibited
Note: Pin used by the Frael Bruc 100 rev.1 for /SLTSL2 signal
Note: according to its service manual, Goldstar FC-200 has composite video signal on this pin
17 A9 O Address bus signals
18 A15 O Address bus signals
19 A11 O Address bus signals
20 A10 O Address bus signals
21 A7 O Address bus signals
22 A6 O Address bus signals
23 A12 O Address bus signals
24 A8 O Address bus signals
25 A14 O Address bus signals
26 A13 O Address bus signals
27 A1 O Address bus signals
28 A0 O Address bus signals
29 A3 O Address bus signals
30 A2 O Address bus signals
31 A5 O Address bus signals
32 A4 O Address bus signals
33 D1 I/O Data bus signals
34 D0 I/O Data bus signals
35 D3 I/O Data bus signals
36 D2 I/O Data bus signals
37 D5 I/O Data bus signals
38 D4 I/O Data bus signals
39 D7 I/O Data bus signals
40 D6 I/O Data bus signals
41 GND PWR Signal ground
42 CLOCK O CPU clock 3.579545MHz
43 GND PWR Signal ground
44 SW1 For insertion/removal protect
45 +5V PWR +5V power source
46 SW2 For insertion/removal protect
47 +5V PWR +5V power source
48 +12V PWR +12V power source
49 SOUNDIN I Sound input signal (-5bdm)
50 -12V PWR -12V power source


  • On some manufacturers, even<->odd pin signal is swapped. Other pinouts might exist (not verified)
  • Signals are TTL compatible.
  • Power source +5V must be 300mA max per slot.
  • Power source -/+12V must be 50mA max for all slots. Not connected on several MSXs.
  • SOUNDIN pin is not connected on several MSXs (Eg Toshiba HX-10DP).

Other expansion bus