The Minitel was a french dumb terminal with an embedded modem which had its Golden Age before the rise of Internet. Typically cubic, with an included CRT screen and, more importantly, you could have one at home for cheap (the model 1 was “lent” for free), so, it was a huge success and a lot of people (including me) had their first experience “being online” playing with that thing. The Minitel 5 was a version really more rare to encounter. Flat, with an LCD screen and contained a rechargeable battery, this “laptop-style” terminal could be used in phone booths and cars.
I’ve got one, but it is very strangely crashing at the second key press. As there seems to be no documentation yet available for it, I made this git repository.
There are two 27C256 EPROM on the Minitel 5 board.
The first is the main EPROM, in socket
MN3, containing all the firmware as the 80C32 microcontroller is ROMless. Beware, as my Minitel 5 is crashing, this ROM may be corrupted. If somebody can dump their own device, it could be very interesting for me to compare.
The second EPROM, in socket
MN8, is connected to the character generation IC and contains solely the bitmap font. 485 ’16-bytes’ zones from 0x6000 to 0x7E5F, with only the first 10 bytes used in each block (the 6 extra are always 0x00), one byte for each line of each character, where each bit is a pixel. Everything before address 0x6000 and from 0x7E50 to the end is filled with 0xFF.
MN1MHS 80C32 (MCU)
MN2MHS MBSR-2000F11-5 DECOPLAT-1
MN3NEC D27C256AD-15 (main EPROM)
MN4Sharp LH5164-10 (backup RAM)
MN5ROM/RAM “dual-dual row” (empty socket)
MN6OKI M6255 (dot matrix lcd controller)
MN7MHS MBSM-2000F05-5 VIDEOPLAT-1)
MN8NEC D27C256AD-15 (bitmap font EPROM)
MN9Philips FCB61C65LL-70T (SRAM)
MN10Philips FCB61C65LL-70T (SRAM)
MN11Motorola HC245A (3–state octal latch)
MN12Motorola HC245A (3–state octal latch)
MN13Motorola HC00A (quad 2-input NAND gate)
MN14Harris HC04 (hex inverter)
MN15Motorola HC245A (3–state octal latch)
MN16Motorola HC245A (3–state octal latch)
MN18Motorola HC4075 (triple 3-input OR gate)
MN19RCA(?) HC273 (octal D latch w/common clock and reset)
MN201ST TSB7513CP (single chip asynchronous FSK modem)
MN202Philips PC74HC4053T (triple 2-channel analog multiplexer/demultiplexer)
MN203TI(?) 27M4C (quad low power CMOS op-amp)
MN204ST EFG71891PD (DTMF generator w/serial input)
MN205Harris HC4052 (dual 4-channel analog multiplexer/demultiplexer)
MA103LM3578N (DIP-8 switching regulator)
MA104ADC0831CCN (single differential input 8-bit ADC w/serial I/O)
MA105LM385M (1.2V micropower voltage reference)
MA203Harris H11AG2 (phototransistor optocouplers)
More to come!
I already have some schematics. But i’m already now fucking tired doing this! 😡
People I wish to thank:
- Ghyom for giving me that ancient device
- Furrtek for his help for recognising Harris old IC logo and the 27M4C op-amp
- Fréderic from CEM de Ronchin for his help in desoldering
- nikiroo for his spellchecks.