theelf wrote on 2023-05-21, 00:26:

[...]
Ok, benchmarks... the difference is HUGE!!!!
[...]

nicely done!!!
but I have a question: what version of DOOM executable also calculates the FPS like you show on the pics?

keropi wrote on 2023-05-21, 08:35:

theelf wrote on 2023-05-21, 00:26:

[...]
Ok, benchmarks... the difference is HUGE!!!!
[...]

nicely done!!!
but I have a question: what version of DOOM executable also calculates the FPS like you show on the pics?

Hi! is fastdoom

FastDoom. A new Doom port for DOS, optimized to be as fast as possible for 386/486 personal computers!

Ah thanks
Never really used it for benchmark

According to datasheet 60Mhz configuration was 88Mhz before E revision.
It might be interesting.

Hi guys!!! dont know if ask here or start a new thread

About this IBM machines, i have some questions, someone managed to find ANY pin, connector, whatever to have a reset button? my good, this ibm pcs miss the most used function in DOS/Win3x 😀

keropi wrote on 2023-05-21, 12:05:

Ah thanks
Never really used it for benchmark

After Fastdoom i dont see any reason to use vanilla doom anymore, only nostalgic reasons. Of course, compare to old benchmarks is a reason

Yes, finally my kingston turbochip on IBM PS/1 see 160Mhz!!! Kid's dream!!!
Thanks epictronics, Thermalwrong

totio wrote on 2023-05-22, 12:22:

Yes, finally my kingston turbochip on IBM PS/1 see 160Mhz!!! Kid's dream!!!
Thanks epictronics, Thermalwrong

Oh thats great!! i will love to have a 486/5x86 +100mhz in my IBM, but i dont find interposer in any place to buy, and overclock my DX4-75 to more than 100mhz i think will not work for sure. What combination did you use for 40mhz bus?

theelf wrote on 2023-05-22, 12:50:

totio wrote on 2023-05-22, 12:22:

Yes, finally my kingston turbochip on IBM PS/1 see 160Mhz!!! Kid's dream!!!
Thanks epictronics, Thermalwrong

Oh thats great!! i will love to have a 486/5x86 +100mhz in my IBM, but i dont find interposer in any place to buy, and overclock my DX4-75 to more than 100mhz i think will not work for sure. What combination did you use for 40mhz bus?

R175 populated only.

totio wrote on 2023-05-22, 13:04:

theelf wrote on 2023-05-22, 12:50:

totio wrote on 2023-05-22, 12:22:

Yes, finally my kingston turbochip on IBM PS/1 see 160Mhz!!! Kid's dream!!!
Thanks epictronics, Thermalwrong

Oh thats great!! i will love to have a 486/5x86 +100mhz in my IBM, but i dont find interposer in any place to buy, and overclock my DX4-75 to more than 100mhz i think will not work for sure. What combination did you use for 40mhz bus?

R175 populated only.

Thanks! yes, i believe, i tested yesterday i did same mod, and no boot, 40x3 is too much for the DX4/75mhz, but i wanted to be sure, thanks

Hi, sorry for bumping this "old" thread. I have an PS1 (2168 552) that uses the same board that the one epictronics shows in his videos. I'd like to upgrade it but i have some questions. I already asked on the general forum, but no luck 🙁 So I guess is better to ask someone that has this computer:

- My main concern is the cache. I want to upgrade it to the maximum amount. ¿Is there any problem if I use faster chips than specified at the manual? I've looked at ebay for the UM61256ck-20 and they're more expensive than other faster 256kb chips. Should I pay attention to anything in special or go for a specific manufacturer? Maybe UMC is better than ISS? The idea is to install 16MB of RAM, altough may be in the future it gets upgraded to more ram (24 or 32 megs) if the games he plans to play don't have problems with that amount of memory.

-I thought that all overdrive chips were the same, but today I've learned that there are some that come with 169 pins instead of 168 pins, so I guess the cheapest and quickest way to upgrade the cpu is hacking the motherboard because a 168pin overdrive 486, should not disable the onboard 486SX. Am I wrong? (I already tried an ODPR and set the jumpers to 486dx, but it didn't work)

-The motherboard uses an hitachi ram chip for the video card. I guess it'll be better to use the same manufacturer for the ram, but do you know if i can use chips, for example, for siemens as long as they run at the same speed and have a compatible pinout?

Thermalwrong wrote on 2023-05-21, 01:09:

maybe IBM put resistors on there for a reason but it shouldn't be necessary since it's only setting some jumpers really - the only thing that's necessary is for the resistance to ground to be lower than the resistance on the pull-up resistors that are internal to the PLL

Sorry for bumping, but I just went thorough my parts drawers and couldn't find any 330 resistors (even though I am pretty sure I have some some where). Do you think it will be safe to just short the resistor pads with a wire or even just a blob of tin? Seems to me the risk of damage is very small?

I kind of want to go ahead right away and don't want to wait for or order a whole roll of suitable surface mount resistors if it's not strictly necessary.

Monteto wrote on 2025-01-27, 20:55:

Thermalwrong wrote on 2023-05-21, 01:09:

Very sorry, just saw that you answered this in this thread: Upgrading a 486SX (IBM PS1). Thank you

Monteto wrote on 2025-01-27, 21:04:

Monteto wrote on 2025-01-27, 20:55:

Thermalwrong wrote on 2023-05-21, 01:09:

Very sorry, just saw that you answered this in this thread: Upgrading a 486SX (IBM PS1). Thank you

Did you ever get around to testing this on yours? I'm in the same boat and don't have the resistors so am contemplating, though hesitantly, just bridging the pads as he suggested but was hoping somebody else had tried it first 😁

Thermalwrong wrote on 2023-05-21, 01:09:

Just watched the video too, thanks for the mention on there epictronics 😀
It was a very well put together video and it's great that this is working in the way that I guessed from the pictures - an educated guess though, I've done similar things with my Toshiba T2130CS laptop.

theelf: That's a pretty good way of getting around that actually. Potentially you could connect up a 3-position DIP switch or jumpers to the S0/S1/S2 lines since that's what the datasheet shows, maybe IBM put resistors on there for a reason but it shouldn't be necessary since it's only setting some jumpers really - the only thing that's necessary is for the resistance to ground to be lower than the resistance on the pull-up resistors that are internal to the PLL

I've tested your theory today, just removed the resistor on 176 and bridged 174 and 175 and it works: