CASIO fx-5200P Scientific Computer teardown

[foroplus]

(06-13-2019 08:57 AM)jebem Wrote:  

(06-12-2019 11:25 AM)foroplus Wrote:  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.

Yes, the oscillator frequency was trimmed at the factory for specific frequencies and we could change it.
However I am not into overclocking things anymore these days, I would say that I am into under-clock machines to save energy
As a collector, I realized that I should leave the machines in the original state as much as possible. Same for my radio collection, I don't even replace defective caps anymore as that would result in a non original radio.

I discovered your nice web site here:
Foro Plus
Lots of manuals, tips, emulators and more.

Yes José, you're right. These are the good criteria for a collector. And I share them.

But sometimes I feel the need to deep into the guts of these machines. Describing only the surface is not enough for me, and I'm saying that, knowing that I am only an amateur without the necessary tech knowledge. But you know, it's a hobby, something to spend the time.
I know that programming Z80 machine code of a TI-83 has no sense, but I like it. All these things, both hardware or software, relaxes me. They recall me my youthhood.

I am a fun of your teardowns. Never miss one.