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Thomson MO5

Introduced in 1984, the Thomson MO5 is the first computer in the MO series. It will be discontinued in 1986, when the MO6 will replace it.

Like most 8bits computers, the MO5 has it's OS (aka Monitor) and a BASIC interpreter built in ROM. The floppy controller comes with an additional ROM, and will automatically boot floppies. The floppies contain an extended BASIC (Disc BASIC) that adds commands to the ROM one, mostly to help with disc access.

There are several versions of the MO5. The first revision is not compatible with the RAM expansion. All the later ones are. The MO5 was later upgraded to get a mechanical keyboard, and there was a “Michel Platini” limited edition (just a different color for the case).

Manuals

ROMs

Boot screen

Specifications

Frequencies

Video

  • 50Hz framerate
  • 16 color palette
  • 320×200 resolution with 8×1 attribute blocks
  • 16KB of video RAM
  • RGB with composite sync output

Audio

  • 1-bit sound through PIA
  • Audio track from tape
  • Output on SCART connector and expansion port

Memories

  • 48K of RAM
  • 16K of ROM
    • 4K for the monitor
    • 12K for the BASIC

Mass storage

  • Tape port
  • Cartridge connector

Keyboard

  • 58 keys
  • Reset button

Dimensions & Weight

Power supply

Connectors

Lightpen

Tape

  • Pin 1: Motor control (set to 0 to spin motor)
  • Pin 2: ground
  • Pin 3: audio input
  • Pin 4: data input
  • Pin 5: data output

All pins except the audio input are TTL levels, straight from the 6821 PIA. The tape port can be used as a generic bit-banged serial port for other applications. The tape drive does all the filtering and cleanup of the tape data itself, and transmitsthe binary level that the computer needs for decoding.

The audio input comes from the second track of the tape drive, which has a stereo head. It is mixed with the 1bit sound from the machine and sent to the audio pins of the SCART connector.

17V input

SCART video

Expansion port

Cartridge port

A (Front)Pin numberB (Back)
A14 1 A15
+5V 2 A12
PRCART 3 A11
A13 4 A10
NCSCART5 A9
D7 6 A8
D6 7 A7
D5 8 A6
D4 9 A5
D3 10A4
D2 11A3
D1 12A2
D0 13A1
GND 14A1
R/-W 15E
  • PRCART is pulled low by the cartridge to hide the BASIC ROM
  • NCSCART is the “chip select” line for the cartridge space. It is active low, for all access to the B000-EFFF memory range.
  • On first revision MO5, the A14, A15, and E signals are missing, making it impossible to use the RAM expansion.

Keyboard

Layout

Mapping

01 234567
0NEFF JHUY76
1,INS KGIT85
2.BACK LFOR94
3@RIGHTMDPE03
4 DOWN BSZ/-2
5XLEFT VQ*A+1
6WUPCRAZENTCNTACCSTOP
7SHIFTBASIC

Circuit diagram

Pictures

Original release

Revision 1

documentations/hardware/mo5.1425227207.txt.gz · Last modified: 2015/03/01 17:26 by pulkomandy
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