Digital Design DDX 80
This page was last modified 18:23, 17 January 2021 by Mars2000you. Based on work by Gdx.



The Digital Design DDX 80 is a cartridge that allows to use the 80 column text mode on a MSX1 computer, it is based on the Motorola 6845 CRTC (Cathode Ray Tube Controller) that adds this mode.

It includes two 8kB ROMs, one with a specififc BIOS, one with character data. The 80 column mode is automatically initialised when booting the MSX with this cartridge inserted in a slot. However, a small button on the cartridge allows the interface to be disabled during startup.

Contrary to the Microsol VMX-80, the BIOS rom does not have its first part mirrored in the second part, because it includes more extra BASIC instructions - see DDX BASIC. Even the instructions for the serial port are present, but they can be used only with the DDX 80T cartridge.

The mapping is done as follows:

  • 4000h - 5FFFh: ROM
  • 6000h - 6001h: access to the MC6845 registers
  • 7000h - 77FFh: MC6845 VRAM (2kB)

It comes with two video cables, one to connect to the MSX composite video output and the other to connect to the TV set or video monitor.

Brand Digital Design
Model DDX 80
Year 1988
Region Brazil
Launch price
Package content
Emulation ROMs dump made, but only the BIOS rom has been decoded for using in emulators.


Digital Design DDX 80
Digital Design DDX 80 PCB
Digital Design DDX 80 PCB (underside)
Digital Design DDX 80 underside
Digital Design DDX 80 with cables
Digital Design DDX 80
Digital Design DDX 80 packaging

System Requirements

  • MSX1 computer with video composite output, one free slot cartridge