Hi all
i am 57 years old and i leave in France, on the 'côte d'azur" between Marseille and Nice.
my native language is french so i can make mistakes in english.
i started computing in the early 80's with commodore VIC 20, commodore 64 and moved next to the 16 bits computers (ATARI)
i always reversed things , programs, devices,...
i have a software initial formation
for some years now i have reversing electronic chessboards from the 80's and 90's.
there were 3 main brands : Fidelity Electronics (USA), Mephisto (Germany) and Novag (?)
their boards are all based on Z80 (a few), 6502 (most of them in the golden age), 68000 and 6301 also.
my work/hobby consists in opening the boards , dump the ROMs, disassemble the program with a tool like IDA_PRO in order to fasten the boards.
for most of the based boards, the factory speed starts from 1.5 Mhz till 4/5 Mhz.
in most cases i am able to put a new WDC65c02-14, and changing RAM and ROMS i am running the boards at speeds from 6 till 18Mhz depending the model and the initial components.
in most cases i also change some of the old 74xx IC towards more modern and fast components of the same reference.
in particular teh 74xx138 which is a selector 8 outputs.
i have also done the same thing on the 2 reversi board i have, made by Fidelity in 1981 and based on 6502(2 Mhz). starting from 1.4 Mhz it is now running at 8 Mhz, but could go faster if i had the right components :
as all of you i can't buy anymore some genuine WDC-10 Mhz, and as most of you i have bought many counterfeits chips from Ebay coming fromChinese sellers.
( i read most of the topics about that).
my mlacks is that on some boards i can't use WDC14Mhz chips (and i do'nt know why) so i am locked to small frequencies.(6/8 Mhz)
i have done about 20 different models of boards at the moment , some in pure plastic, some wooden and contribute to the MAME emulator for the chess boards, adding in MAME all new boards i open and dump.
i also work on some 68000 based boards but that is of-topic and i don't want to be fired at the first day in that forum
i speeded up some of them from 12 to 16 Mhz or to 16 to 20 Mhz
i have been a guest for many quarters and decided to register to collaborate.
of course i have more questions than responses, and this forum dedicated to 6502 seems to be the right place as it is focused on the 6502 and its variants, whatever is their use.
in some chess hardware forums, the modders adopt the lazy approach : they change the clock and if it works, they are happy.
but without modifiying the software when necessary they are locked to small upgrades.
i act differently :i first reverse (software and hardware) and if i can speed up the boards i am happy.
i success in most cases even if i am locked sometimes and that is why i am here.
for some Fidelity boards i go from 3 Mhz (factory speed) to 16 Mhz after modifications.
i would say that i have a good idea of how those boards work, having identified the main blocks of hardware and software and how they interact.
of course that hobby is very time consuming and also money consuming as the chess boards are becoming expensive because of the vintage/retro mode.
i have a PC-based logic analyser, a PC-based oscillo and a solder station.
regards.