Reply 55600 of 56726, by PC@LIVE
- Rank
- Oldbie
PD2JK wrote on 2024-12-30, 10:17:Indeed interesting. I also see a DIP switch block between the 25MHz crystal and the CPU. Usually the CPU speed is half the oscil […]
PC@LIVE wrote on 2024-12-30, 09:03:...and although it already has a 286 16 MHz, I thought that this a 286 12 MHz....
Indeed interesting. I also see a DIP switch block between the 25MHz crystal and the CPU.
Usually the CPU speed is half the oscillator frequency, however I have seen 48MHz crystals being used for 12MHz CPU's, then the frequency is divided by four I guess.
Someone correct me if I'm wrong.
Yes Thanks ☺️ it's a card quite similar to the one I had in the early 90s on the PC in the office, let's say it's the previous version, however the clock is 12 MHz, and I've already identified the card, it would be the same (or produced with another brand) to this one:
https://theretroweb.com/motherboards/s/cdtek-gh286-g2-ii
From the manual I saw that the switch is used to select the amount of RAM present, in case it is added or removed, it is necessary to change the position of n. 2 3 and 4.
For quartz I don't know, they usually go at half frequency, and I saw that there is the 25MHz one, maybe what you saw is a 48KHz, I don't know what it's for, but it's usually present in all the old motherboards.
AMD 286-16 287-10 4MB HD 45MB VGA 256KB
AMD 386DX-40 Intel 387 8MB HD 81MB VGA 256KB
Cyrix 486DLC-40 IIT387-40 8MB VGA 512KB
AMD 5X86-133 16MB VGA VLB CL5428 2MB and many others
AMD K62+ 550 SOYO 5EMA+ and many others
AST Pentium Pro 200 MHz L2 256KB