I have an unknown 486 Symphony Chipset motherboard..
It is working with a 486 DX50 no problems.
I have tried two different 486 DX2 chips and neither will boot. I am not sure if there is a dipswitch setting that needs to be set for the DX2-66 ?
That board seems to have a 50MHz crystal oscillator. To run a DX2-66 you need a 33MHz one.
So if you just put in the DX2, it is clocked with 50MHz, internally with 100MHz, no 66MHz type can do that.
Odd that the board has 50Mhz XTAL and ran the DX50 at 50Mhz. Seems every XTAL controlled 486 board I have seen the CPU clock runs 1/2 Xtal.
Can't seem to find a decent manual yet
Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun
I have a similar Symphony board, but it's a DTK and has more jumpers on it (PKM-0031Y). I believe every CPU in the manual uses an oscillator that is double the bus speed, EXCEPT for the DX50, which needs a 50MHz oscillator. However, on your board I don't seem any jumpers to configure the oscillator, so I would guess all CPUs installed use a oscillator of the same speed.
BTW, it's pretty cool you have an all ISA board that can take 1MB cache. Not to mention all eight ISA slots are full length.
"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium
Yes, obviously it is 1:1 here, he used a DX-50 and there is a 50MHz oscillator 😀
I agree, it's a very cool board, it cries for upgrading the cache 😁
The cache SRAMs that are now on the board seem to be quite slow with 25ns, I think too slow to do 2-1-1-1 timing on 33MHz, maybe just fast enough for a 3-2-2-2 timing on 50MHz.
Another reason for upgrading it.
On the other hand even with 1MB SRAM propably not the fastest board (but still nice).
Agreed, the cache chips are way too slow for 50MHz. Even at 33MHz 20ns parts are used. Ideally for 50MHz you should have 12ns cache, but most had 15ns.
Maybe whoever assembled the PC had access to a memory tester and determined that the parts worked faster than their markings.
"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium
Late to the party, I know. Settings for this board are here:
https://www.ultimateretro.net/en/motherboards/5502
If you manage to get a bios string/dump that would be nice, it might actually identify the board manufacturer.
Whoa yeah 2.5 years late. But most of the posters are still active.
I think that might be the board I had in my old ISA 486 DX2/50. I had a little collection of oscillators for my overclocking shenanigans.
