Friday, April 3, 2020

Dumping an MCU from 1986 (HMCS40 - ALPHA-8505)

Last year i bought a big lot of gambling boards from an local operator. Inside this lot were four complete boards from an unknown game marked as BINGO TIME on an included sheet.

After all roms got dumped and submitted to MAME, it was pretty fast discovered that it fits perfectly into the "equites.cpp" driver.
The game also booted but got stuck at this screen:

If you look closer at the board you will find the ALPHA-8505 chip.

This chip is from the HMCS40 chip-family and we even already have dumps from the ALPHA-8303 in MAME. These were only possible because Tatsuyuki Satoh built the 8201 dumper back in 2003-2008. This dumper uses the LPT-port of an WindowsXP computer.

While i built that dumper already in 2019, for dumping the ALPHA-8505, i did not get good dumps with it. That way i thought the 8505 is different to the other supported chips.

As the four boards were on my shelf since months and i saw it mostly every day, i got interested in it again the last few days and rebuilt the complete dumper from scratch today.

I also used another old WindowsXP machine with the dumper. This time i got better results, the program ran through all pages of the testmode and within some seconds i got a 8kb file from it.

Comparing that file with the existing 8303 dump it mostly matched and only had 169 differences! I redumped all four of my 8505 chips and always got the same dumping result!

After sending the dump to MAME, i shortly after got the confirmation that the dump is good and the game boots through the romcheck.

The game is marked as working now, but without sound. Someone has to take a closer look at the sound-emulation, as this is currently not supported.

As we will need this dumper for some other currently missing ALPHA-8*** mcu's also in the future and as it's more complicated to solder the complete dumper by hand, i designed this little board:

The PCBs are already in production and should arrive here in the next few weeks, making it really easy to reproduce this dumper for more people in the world. (You only will need a WindowsXP machine with an real (no USB) LPT-port).
For the external +5v power it has a Mini-USB-Port which you can just connect to the usb-ports from your computer.

Thanks to Ivan for adding the game to MAME and to Tatsuyuki Satoh for making this dumper. Another rare game completely preserved.