Pioneer UC-V102
This page was last modified 10:32, 17 December 2021 by Mars2000you. Based on work by Rderooy and Gdx and others.



The Pioneer UC-V102, also called O-THE, is a Videodisc controller for "Level 3" interactive systems. It is meant to be used in combination with a LaserDisc player and the optional SS-D1 video buffer and digitizer. It was marketed in Japan, Europe and the US. The system is really an MSX2, but without the MSX logo.

Unlike most hdden MSX systems, getting to MSX-BASIC and running MSX software on it is very easy. If you switch it on, you will not see the MSX boot logo, but you will go straight to the MSX-BASIC 2.0 prompt. Disks and cartridges can be used just like with any other MSX system.

By default, this computer has only 1 built-in disk drive, but there is a location to add a second disk drive (? reference HXP101).

This machine has 6 internal expansion slots. Each column of three slots goes to a connector in motherboard, named "Expansion SLOT A" or "Expansion SLOT B". Pioneer sold some expansion boards to use in UC-V102:

  • the UK-V103 digitizer board
  • the UK-V104 RS-232C board (with two UK-V104 boards, the Pioneer UC-V102 could control up to five LaserDiscs players and touch screens (available under the reference UK-V105)

The separate keyboard of the Japanese version (with reference UK-V101) is the same as for the Mitsubishi ML-G30 Model 1 and ML-G30 Model 2.

For the European and American versions, the keyboard (? reference UK-V102) is probably similar to the Mitsubishi ML-G3 keyboard without the typical Spanish keys.

Brand Pioneer (Manufacturer: Mitsubishi)
Model UC-V102
Year 1987
Region Europe, Japan, US
Launch price
RAM 64kB in slot 0-2
VRAM 128kB
Media MSX cartridges, 2DD floppy disks
Video Yamaha V9938
Audio PSG
Chipset Yamaha S1985
Keyboard layout (JP) QWERTY/JIS + numeric keypad
(Europe/US) QWERTY + numeric keypad
Extras One 720kB 3,5" floppy disk drive (the second was sold separately), reset button, Kanji-ROM level 1, RS-232C interface + RS-232C BASIC, superimposer, mono/stereo switch for LaserDisc sound
Emulation ROMs dumped and emulated (Japanese version)


Pioneer UC-V102 computer
Pioneer UC-V102 back
Pioneer UC-V102 label
UC-V102 main PCB (bottom)
UC-V102 part of main PCB
Pioneer UC-V102 with keyboard
Pioneer UC-V102 inside
UC-V102 internal expansion slots
Pioneer UK-V101 keyboard


The Pioneer UC-V102 is a MSX2 with one cartridge slot and 6 internal expansion slots, a Z80A from Sharp (LH0080A) and an MSX-Engine S1985 from Yamaha.

The main RAM is present on slot 0-2, a configuration that can cause poorly written software to crash. Also, with this layout, the POKE-1,(15-PEEK(-1)\16)*17 trick to workaround buggy software that does not handle subslots properly will cause this machine to freeze.

Slot Map

Slot Slot Slot
0-0 0-1 0-2 0-3 Slot 1 2-0 2-1 2-2 2-3 3-0 3-1 3-2 3-3
Page C000h~FFFFh 64kB
Page 8000h~BFFFh
Page 4000h~7FFFh Main-ROM RS-232C
Page 0000h~3FFFh Sub-ROM Disk ROM
  • The RS-232C ROM is a 8kB ROM - 4000h-5FFFh
  • ES = Expansion Slot - Each Internal Expansion card slot connects to two sub-slots


  • RGB output (SCART)
  • Three sets of RCA Video+Audio input connectors
  • One set of RCA Video+Audio output connectors
  • Keyboard connector (Hirose QM40-26PA-EP)
  • RS-232C connector (DB-25)
  • Centronics compatible Parallel port for a printer
  • 2 general connectors (Joysticks, Mouse, Paddle controllers, etc)
  • 1 cartridge slot
  • Three 100-pin custom expansion card slots
  • AC Outlet

Note: No Data recorder connector!

External Links