Robhalfordfan wrote on 2020-08-29, 19:25:

would having more cache help in any way other than more ram higher than 32mb

For a constant amount of RAM (under the cacheable limit) the more cache you have, the higher % of the time the CPU can get data from cache instead of RAM (Hit Rate). If what you're getting at is if you have more than minimum cache for all RAM to be cacheable, will the rest be used--yes it will. However, since you're sticking with a 486DX2 and 16-24MB RAM, 256KB external cache is fine. Plenty of systems were sold with 4MB RAM & no cache at all.

Once you get your system up and running, since your bus will be 33MHz, you can play around with cache timing & DRAM wait states to get them as minimal as possible.

Robhalfordfan wrote on 2020-08-29, 19:25:

would prob keep it dx2 - 66mhz for a while and use somewhere between 16-25mb ram and use edo ram (as i have loads of sticks)

That it is EDO is important as mentioned earlier; the ATC-1415 is labeled as supporting EDO. Hopefully that works out for you.

jakethompson1 wrote on 2020-08-29, 19:38:

For a constant amount of RAM (under the cacheable limit) the more cache you have, the higher % of the time the CPU can get data […]
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Robhalfordfan wrote on 2020-08-29, 19:25:

would having more cache help in any way other than more ram higher than 32mb

For a constant amount of RAM (under the cacheable limit) the more cache you have, the higher % of the time the CPU can get data from cache instead of RAM (Hit Rate). If what you're getting at is if you have more than minimum cache for all RAM to be cacheable, will the rest be used--yes it will. However, since you're sticking with a 486DX2 and 16-24MB RAM, 256KB external cache is fine. Plenty of systems were sold with 4MB RAM & no cache at all.

Once you get your system up and running, since your bus will be 33MHz, you can play around with cache timing & DRAM wait states to get them as minimal as possible.

Robhalfordfan wrote on 2020-08-29, 19:25:

would prob keep it dx2 - 66mhz for a while and use somewhere between 16-25mb ram and use edo ram (as i have loads of sticks)

That it is EDO is important as mentioned earlier; the ATC-1415 is labeled as supporting EDO. Hopefully that works out for you.

ok dokey will keep in mind as it has ide integrated but no floppy on mobo as will need to a floppy controller card but as i said it help narrow down what i am looking for

i think i manage to work out why the old mobo wouldn't boot or post - think the cpu that came with it is dead

i got another socket 3 mobo (ACORP 486 - LS-486E rev:C2 (rebranded i think and tested and working) and same thing as before - no post/boot

manage to source another 486 dx2 66 which is the code is SX955 and the suspected dead dx2 is a SX911 and the only different i can see is that the sx955 supports write-back (not sure if that is better of not) which the SX911 doesn't

will post here and see if a dead cpu was the issue all along when the replacement one arrives

Robhalfordfan wrote on 2020-09-07, 15:49:

manage to source another 486 dx2 66 which is the code is SX955 and the suspected dead dx2 is a SX911 and the only different i can see is that the sx955 supports write-back (not sure if that is better of not) which the SX911 doesn't

Yes, the write-back L1 cache postpones writes to L2 cache & RAM for as long as possible thereby keeping the CPU running at full 66 MHz more of the time rather than waiting around for cache and RAM.

Just be careful with the voltage setting as Intel's 486DX2WB is 5 volts while the AMD equivalent is 3.3.

jakethompson1 wrote on 2020-09-07, 16:42:

Robhalfordfan wrote on 2020-09-07, 15:49:

manage to source another 486 dx2 66 which is the code is SX955 and the suspected dead dx2 is a SX911 and the only different i can see is that the sx955 supports write-back (not sure if that is better of not) which the SX911 doesn't

Yes, the write-back L1 cache postpones writes to L2 cache & RAM for as long as possible thereby keeping the CPU running at full 66 MHz more of the time rather than waiting around for cache and RAM.

Just be careful with the voltage setting as Intel's 486DX2WB is 5 volts while the AMD equivalent is 3.3.

thank you 😀

i have set the jumpers on the mobo to 5v and fingers crossed it works as it will tell me that it was a dead cpu all along that was wrong

i am officially confused

the new cpu arrived and same issue no boot/post on new socket 3 mobo

also have tried

new cpu in new mobo - nothing
new cpu in old mobo - nothing
old cpu in new mobo - nothing
old cpu in old mobo - nothing (original)

try all with the psu that came with pc and with spare psu (to rule out the psu) still nothing

also try reseating the ram and cards etc - still nothing

try a diffrent graphics card - still nothing

i have also try my old penitum 133 mobo with my penitum 133 and that works no issues with psu, graphic card, sound card, hdd, cd-rom drive, floppy drive that came with pc to also rule out the psu and work no problem

what could causing the all this as i have set the jumpers according the manual i found

https://www.elhvb.com/webhq/models/486pci/ls486ec2.htm

You want to eliminate bottle necks that will hamper performance.

Bottle necks to consider.

1) Hard drive vs. CF card or SSD.
2) Video card performance.
3) CPU performance. That motherboard may support faster CPU’s like 486dx4-100 or 5x86-133

Either way that motherboard is a good choice and start.
PCI motherboard often perform about 15% to 20% better than VLB motherboard with the same CPU.

In the end you will NOT be satisfied because a Good DOS computer requires the power of a Pentium 75 or higher for good DOS game playback in most games.

With the Pentium CPU you can always disable cache in bios to slow it down to a 386 or 486.
And it will work fine at any of these speeds.

With the motherboard you have selected you can slow it down to a 286 or 386 by disabling cache in bios.
For game play of CPU speed critical DOS games.

But from my experience the Pentium 75 thru 233 is the best choice to support the most DOS game playback in good performance
As the developers of the games intended it to be played.

The power of the pentium play games smooth with good performance and audio playback is good too at any speed.

I would say your biggest bottle neck will be the hard drive.
A CF card or SSD will offer better performance. And should be your first consideration.
Then the video card and then the CPU should be your last consideration for that motherboard.

But a 486dx4-100 will only offer about a 10% performance boost over the 486dx-66
And the 5x86-133 will only offer about a 20% performance boost over the 486dx-66

From the bench marks I have seen and from my personal experience.

Good luck.

thank you and maybe in the future but doesn't help if i can't the socket 3 mobo to post or boot with a dx2 - 66

i also have penitum 200 mmx machine (maybe max out to the 233, one day) that is more for windows 95 early 3d gaming (96/97 max) and very late dos games where 486-66 isnt the best

this machine is more for the early dos games from mid 80s till somewhere 93/94

hello all

i got a mobo replacement for same seller as before and this ones work, boots and post, get in to bios etc

the mobo that works is atc-1415 and got a controller card (GoldStar Electron Prime 2 Super Multi I/O card) on the way as this mobo only has integrated ide but no floppy, serial or parallel ports headers on the board

almost there to get fully working 486 machine and having a test and mess about with it and naturally play some old dos games 😀 and see if i want to do upgrades in future (maybe one or two with time but try and get use to what i have right now to get a good feel for it)

i still baffled why the first two mobos wouldn't boot or post

hello all

i am getting there with this build and so far, i am having fun 😀

i was wondering if it worth upgrading the cd-rom drive to a faster one as the one that came with pc is a double speed drive, is that era-ish appropriate or would 4x or 8x be better and play nice with 486

since the mobo i am using has no floppy header or serial/Parallel headers on-board, i am using a controller card (which i am not 100% happy with it) but it works for now

the controller card i am using has floppy/ide headers and build in parallel and serial (on the backplate/bracket) that plugs in one the headers and a gameport header

i was wondering and looking for a controller card that has only headers for 1x floppy, 2x serial, 1x parallel on it but with a blank backplate/bracket (doubt such cards exist - no harm in asking)

if not, where can i find a backplate/bracket replacement with only the parallel port at the bottom end of bracket (not the middle)

2x or 4x would be era appropriate, even 8x if you were a bit late to upgrade an existing PC.
If you have the drives I'd maybe do it but wouldn't spend money on drives that old as good chance they are nearing the end of their life unless you prepared to service them.

ok thank you, i went for 8x for little overhead