Hey,
Radiochris: If you are still there (probably not) after one year since your last post, but anyway I'll give it a shot. I would like your design. But i would rather buy a cable from you at a cheap price if that is possible. I dont have time nor motivation to build my own, but if that is the only option i would very much like the schematics.
I own a Casio CFX-9850G Plus as well, i wanted to try and connect it to PC and try transfer data between. I wanted to try code assembler programs for it since some guy hacked the calculator and found out most of the instruction-opcodes, but since the calculator is so old and it only has RS232-communication transfering theres a problem of course. My laptop dont have serial or com-connector output, only USB. But i searched the net and found the cable if i want buy it, but its so damn expensice. Its called PC-Link cable and some british/english- company is still selling it. also must buy a RS232 to USB interface. I dont know if it will work in Vista either, thats why i ask if someone has allready tried this?? and got it to work??
Also i read somewhere that the transmissios-speed has to be somewhere around 9600 bytes/sec, i wonder how that'll work on vista. I wonder if i have to code a software-tool for myself to handle this transmission. since i know C++ i dont think that should be much of a problem. The problem is the hardware and if that would work via USB on modern operating systems like Vista.
Unfortunatelly, i think the best option it is to use the RS232 Casio cable + the RS232 to USB.
These converter cables are tricky, some of them. I have one at home. I haven't used in years. I will give it a try this weekend, and i will post pictures about it. Maybe it can help people to build their casio cables, as the preceding project was quite a year old.
I have to say, that the quickest solution for this problem it is to buy the original CASIO cable, and it is NOT so expensive. Are 18 US$ expensive?. Ok, anyways. you can build one for yourself at half the price.
The combination from casio + RS-232 to USB and the FA-122 or FA-123 software it is just fine.
On Casio Page tells FA-123 software can work with Windows® 3.1/Windows® 95/Windows® 98.
I have Windows XP at home so, it works fine. I haven't tested on Windows Vista, but i think it will work fine too.