CASIO fx-5200P Scientific Computer teardown

[foroplus]

(06-12-2019 07:37 AM)jebem Wrote:  

(06-11-2019 07:31 PM)foroplus Wrote:  Wow. According to the dates printed on the chips and the back metal cover, your calculator is dated as of 1992, while mine is on 1985.
That means this machine was a bunch of years on the market.

That was the reason I didn't put a manufacturing date on this specimen as I usually do after dismantling my machines.

I am not sure about the Japanese date codes. They are not well known and documented imho.

Casio was well known for releasing new models every single year, meaning that each model would have relatively short production lifetime, maybe 2 or 3 years.

1985 to 1986 is the mentioned production years for this model in the usual internet portals, but no one knows for sure.
Probably not even Casio would know by now.

In my calculator I am sure the chips are the original ones, as there is no marks of resoldering anywhere.
So a lifespan of 7 years in production seems improbable for Casio, but we never know.

Yes, it's very weird a lifespan of seven years (or who knows if more); but has to be legit since the date is on the very chips and no doubt about that.

Mine is
Both chips were made on November 85.

By the way, have you tried to overclock any of these calculators that have the processor HD61747/HD61913/HD61917?. They have an internal clock which speed can be modified depending on resistor soldered to pins 25 and 26.
Some calculators have a 68K Ohms resistors (this one), and others, like the PB100 a 56K.
Seems to be that if you solder another resistor in parallel with that one, the speed of the clock is increased an thus the performance of the machine (and so the energy draining). A 30K resistor will double the speed, and a 3,3K will triple it.