New Project:
80287 Clock Board.
it allows to clock 287 FPU at different Clockrate.
For Example to run 6Mhz 286 with 20Mhz FPU.
Not yet tested 😀
i will order it after moving on 5.11
Cool! 😎👍
Um, if I'm allowed to make an advice..
Maybe the crystal oscillator can be buffered, for an even cleaner TTL signal.
Because, I had issues myself with a modded Mega Drive..
My 68010 isn't exactly stable with the separate clock. Another user fixed this issue with an HD74LS14, I think.
That's why it came to mind.
"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel
//My video channel//
Its buffered trough the 4bit Counter, i think this should suffice.
But it seems like i can omit the counter.. and instead use a oscillator directly.
Then maybe a single buffer gate would be enough.
Madao checked his Adapter.
And it does not care about the 287 datasheet and 33% Duty Cycle and its working.
Data:
Proud Test Canidates arrived!
More Pictures from Madao:
so 50:50 Duty Cycle will suit all 287 well.
i'm back into this.
FPU | Oscillator JP | CKM | Resulting Clock | Supported
--------|----------------|------|----------------|----------
80287 | JP5 (20MHz)* | LOW | 6.667MHz | YES
80287 | JP1 (25MHz) | LOW | 8.333MHz | YES
80287 | JP2 (30MHz) | LOW | 10MHz | YES
80287 | JP3 (32MHz) | LOW | 10.667MHz | YES
80287 | JP4 (36MHz)* | LOW | 12MHz | YES
80287 | JP5 (20MHz)* | HIGH | 20MHz | YES
80287 | JP1 (25MHz) | HIGH | 25MHz | YES
80287 | JP2 (30MHz) | HIGH | 30MHz | NO
80287 | JP3 (32MHz) | HIGH | 32MHz | NO
80287 | JP4 (36MHz)* | HIGH | 36MHz | NO
80287XL | JP5 (20MHz)* | LOW | 10MHz | YES
80287XL | JP1 (25MHz) | LOW | 12.5MHz | YES
80287XL | JP2 (30MHz) | LOW | 15MHz | YES
80287XL | JP3 (32MHz) | LOW | 16MHz | YES
80287XL | JP4 (36MHz)* | LOW | 18MHz | YES
80287XL | JP5 (20MHz)* | HIGH | 20MHz | YES
80287XL | JP1 (25MHz) | HIGH | 25MHz | YES
80287XL | JP2 (30MHz) | HIGH | 30MHz | NO
80287XL | JP3 (32MHz) | HIGH | 32MHz | NO
80287XL | JP4 (36MHz)* | HIGH | 36MHz | NO
(Table covers almost all possible combinations, regardless how useful they are)
This Oscillators should cover few Clockrates, any suggestions, idea's ?
I bought an Si531 PLL module, but it seems that I can't get the IC anywhere.That's why I'm now trying to cover as many clock rates as possible with as few oscillators as possible.
