Casio MX-15
This page was last modified 10:05, 24 August 2021 by Mars2000you. Based on work by Gdx and Rderooy and others.



The MX-15 is the international version of the Casio MX-10. This model was sold in several countries, including Spain and Thailand. It has a low quality, rubber domed keyboard with 'International' QWERTY layout.

Unlike the MX-10, the tape interface is actually built inside the machine and the tape connector is standard (as is also the case on the PV-16).

The keyboard features special blue Joypad keys arranged in a diamond-shape (without the 'Joypad 1' indication). Together with the TR1 and TR2 keys on the bottom left of the computer, these are the equivalent to a joystick inserted into joystick port 1. Probably, only the games that use the BIOS routines to handle the joysticks are supported by this internal joypad, this includes BASIC games using the STICK command (needs confirmation).

Apart from the 'Joypad 1' keys, the computer also features normal cursor keys aligned above the joypad keys, but the layout makes them impractical for use in games.

Thr version sold in Thailand had an English/Thai language sticker on keyboard buttons.

It's possible to add two cartridge slots and the missing printer port, by combining this computer with the expansion unit KB-15. The computers power supply is not internal, the provided AC power adaptor (AD-4175) is required if you don't use the KB-15 unit, which has its own power supply.

Brand Casio
Model MX-15
Year 1986
Region Spain, Thailand
Launch price
RAM 16kB in slot 0 (with or without KB-15)
Media MSX cartridges
Video Toshiba T6950
Audio PSG (AY-3-8910)
Chipset None (separate ICs whose a gate array Hitachi HG61H06)
Keyboard layout QWERTY
Extras Two specific keys TR1 and TR2, Joypad 1 cursors, (with KB-15) third cartridge slot
Emulation ROM dumped and emulated.


Casio MX-15
Casio MX-15 back
MX-15 box & manual (Spain)
Casio MX-15 underside
Casio MX-15 left side with standard cable in tape connector
MX-15 close-up of Thai keyboard
Casio MX-15 left side
Casio MX-15 right side


The Casio MX-15 is a MSX1 with a Z80A from NEC (DA780C-1), and a Hitachi HG61H06 gate array (seems to implement at least the PPI).

The pins SW1, SW2, -12V and +12V of the cartridge connector are not connected. In general, MSXs without a protection switch have pins SW1 and SW2 connected to GND. A few rare cartridges use SW1 and SW2 as GND and some cartridges need the -/+12V as for example the FM-PAC.

The AC power adaptor output is 7V with center negative, 800mA. It is not useful with the expansion unit.

The VDP used is the Toshiba T6950, which does not support some undocumented features of the Texas Instruments TMS9918, TMS9928 and TMS9929 VDP's.

Slot Map without KB-15

Slot 0 Slot 1 Slot 2 Slot 3
Page C000h~FFFFh RAM Cartridge
Page 8000h~BFFFh
Page 4000h~7FFFh Main-ROM
Page 0000h~3FFFh

Slot Map with KB-15

Slot 0 Slot 1 Slot 2 Slot 3
Page C000h~FFFFh RAM Cartridge
Page 8000h~BFFFh
Page 4000h~7FFFh Main-ROM
Page 0000h~3FFFh


  • RF output
  • Analog sound output (mono)
  • Composite video output
  • Data Recorder connector
  • Centronics compatible Parallel port for a printer (on the left side of the KB-15 expansion)
  • 2 general connectors (Joysticks, Mice, Paddle controllers, etc)
  • 1 cartridge slot (without KB-15) or 3 cartridge slots (with KB-15)
  • 1 expansion bus slot for KB-15 unit
  • AC power adaptor connector