VOGONS


First post, by OSkar000

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I have been trying to upgrade one of my 486 machines to a Pentium OverDrive 83 and doesn't go so well.

Installing the CPU and setting the jumpers correctly, no problem
Booting from one of the IDE harddrive, no problem
Running Quake at 18 fps, no problem!
Running Speedsys and other benchmarks, no problem
Booting with IDE and SCSI harddrives connected, hangs on boot after the boot menu from NT 3.51 when trying to start DOS or NT
Booting from floppy, hangs at first try
Reading floppy disks... hangs after a while

All jumpers are set according to the manual.
I have tried different settings for memory timings and cache. No difference, but its damn fast with everything set as tightly as possible.. and stable, except from when reading floppys
Tried two different floppy controllers with the same result. One ISA (scsi-card) and one VLB (ide/io-controller.
It boots fine from floppy when no hard drives are connected. But as soon as I introduce another device in the system it hangs on boot. So only IDE, SCSI or floppy works fine.

I put the old CPU back, a DX4/120 and everything works as it should... Boots from floppy with all hard drives connected without issues.

I have not tried to find a newer BIOS for it. That might solve the problem...

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Boot screen.

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My very well organized desk 😀

Reply 1 of 14, by TheMobRules

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First of all, try to get the latest BIOS from ASUS (it's from 1999 and should be easy to find). That may solve your problem.

If that doesn't help, keep in mind that the POD83 + L1 WB cache combination can be problematic with symptoms similar to what you are experiencing. Set the jumpers for L1 WT and see what happens.

Reply 2 of 14, by Jasin Natael

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IMHO overdrives aren't worth it. They had a purpose when they were released but in this day and age it is entirely not worth it. The performance uplift you will get will be marginal and nowhere near a "real" Pentium.

I can understand the draw in having your personal retro 486 "maxed" out.....but you are better off building a cheap socket 7 or socket 370 build.

Reply 3 of 14, by OSkar000

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TheMobRules wrote on 2021-04-20, 19:01:

First of all, try to get the latest BIOS from ASUS (it's from 1999 and should be easy to find). That may solve your problem.

If that doesn't help, keep in mind that the POD83 + L1 WB cache combination can be problematic with symptoms similar to what you are experiencing. Set the jumpers for L1 WT and see what happens.

I found a beta bios, 0402.001. I will try that as a first step.

I have tried changing writeback/writethru in the bios but not on the motherboard. Also something i will try.
Is it JP21 that controls the L2 cache? The manual is not very detailed in this area.

Reply 4 of 14, by OSkar000

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Jasin Natael wrote on 2021-04-20, 19:21:

IMHO overdrives aren't worth it. They had a purpose when they were released but in this day and age it is entirely not worth it. The performance uplift you will get will be marginal and nowhere near a "real" Pentium.

I can understand the draw in having your personal retro 486 "maxed" out.....but you are better off building a cheap socket 7 or socket 370 build.

This build is just for fun and not for making it useful. If I can't get it running properly I have other 486 systems where the POD could be used.

I have plenty of other systems if I need the performance and/or compability. From XT up to Pentium 3 and early socket A systems 😀

Reply 5 of 14, by Jasin Natael

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OSkar000 wrote on 2021-04-20, 19:37:
Jasin Natael wrote on 2021-04-20, 19:21:

IMHO overdrives aren't worth it. They had a purpose when they were released but in this day and age it is entirely not worth it. The performance uplift you will get will be marginal and nowhere near a "real" Pentium.

I can understand the draw in having your personal retro 486 "maxed" out.....but you are better off building a cheap socket 7 or socket 370 build.

This build is just for fun and not for making it useful. If I can't get it running properly I have other 486 systems where the POD could be used.

I have plenty of other systems if I need the performance and/or compability. From XT up to Pentium 3 and early socket A systems 😀

Fair enough, I can understand that.

Reply 6 of 14, by TheMobRules

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OSkar000 wrote on 2021-04-20, 19:30:

I have tried changing writeback/writethru in the bios but not on the motherboard. Also something i will try.
Is it JP21 that controls the L2 cache? The manual is not very detailed in this area.

Yeah, according to this site, you need to place a jumper cap over JP21 2-3 to set L1 cache to WT. After that make sure you also set L1 to WT in the BIOS (I don't think changing just the BIOS setting is going to have any effect, you definitely need to set the jumper).

I have an earlier revision of the board, which uses different jumpers and doesn't even support the POD83 properly, but I believe that page is accurate for v2.x.

Reply 7 of 14, by OSkar000

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TheMobRules wrote on 2021-04-20, 20:17:
OSkar000 wrote on 2021-04-20, 19:30:

I have tried changing writeback/writethru in the bios but not on the motherboard. Also something i will try.
Is it JP21 that controls the L2 cache? The manual is not very detailed in this area.

Yeah, according to this site, you need to place a jumper cap over JP21 2-3 to set L1 cache to WT. After that make sure you also set L1 to WT in the BIOS (I don't think changing just the BIOS setting is going to have any effect, you definitely need to set the jumper).

I have an earlier revision of the board, which uses different jumpers and doesn't even support the POD83 properly, but I believe that page is accurate for v2.x.

As I and some friends suspected... this did the trick.

Setting the L2 cache to Write Thru in bios wasn't enough but with the jumpers set to Write Thru it seems to work properly.

Did some quick tests in Quake and got 15.4 fps in the time demo from Phils dosbench pack. Does that seem to be a correct value?

Reply 8 of 14, by furan

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Jasin Natael wrote on 2021-04-20, 19:21:

IMHO overdrives aren't worth it. ....nowhere near a "real" Pentium.

I disagree. You get Pentium floating point performance on a 486, so something like Quake will run well, and it has twice as much cache as the usual 486. So, if you have a 486 w/VLB + PCI that you like, the 83MHz overdrive is pretty neat - and worth it. You sound more interested in DOS games and fine with the Pentium III era hardware, and that's fine, but these forums are about general old hardware.

I'm going to guess you've not even used the chip.

Last edited by furan on 2021-04-21, 22:31. Edited 1 time in total.

Reply 9 of 14, by debs3759

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Jasin Natael wrote on 2021-04-20, 19:21:

IMHO overdrives aren't worth it. They had a purpose when they were released but in this day and age it is entirely not worth it. The performance uplift you will get will be marginal and nowhere near a "real" Pentium.

I can understand the draw in having your personal retro 486 "maxed" out.....but you are better off building a cheap socket 7 or socket 370 build.

That's an odd attitude in a forum where many of us are collectors who want the most out of each platform we collect.

See my graphics card database at www.gpuzoo.com
Constantly being worked on. Feel free to message me with any corrections or details of cards you would like me to research and add.

Reply 10 of 14, by maxtherabbit

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I actually just upgraded a system from a POD63 to an Am5x86 133. The AMD is faster at stock clocks and blows the POD63 away at 160MHz. If the POD could be overclocked to 100MHz I'm sure it would regain the lead but sadly it wasn't even stable at 83

Reply 11 of 14, by furan

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maxtherabbit wrote on 2021-04-21, 23:34:

I actually just upgraded a system from a POD63 to an Am5x86 133. The AMD is faster at stock clocks and blows the POD63 away at 160MHz. If the POD could be overclocked to 100MHz I'm sure it would regain the lead but sadly it wasn't even stable at 83

I'm not sure what your point is, but I'm sure it's in there somewhere. The only real benefit with the Pentium is floating point. Maybe you're not happy with the PODP5V63 being unable to go past its rated speed? Are you surprised that having twice the clock speed makes one chip blow away another?

Reply 12 of 14, by maxtherabbit

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My point is that even if your focus is "maxing" the 486 platform, there is a good chance that the POD will still be inferior to a true 486 processor, unless of course you *only* care about quake benchmarks

Reply 13 of 14, by amadeus777999

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furan wrote on 2021-04-21, 22:14:
Jasin Natael wrote on 2021-04-20, 19:21:

IMHO overdrives aren't worth it. ....nowhere near a "real" Pentium.

I disagree. You get Pentium floating point performance on a 486, so something like Quake will run well, and it has twice as much cache as the usual 486. So, if you have a 486 w/VLB + PCI that you like, the 83MHz overdrive is pretty neat - and worth it. You sound more interested in DOS games and fine with the Pentium III era hardware, and that's fine, but these forums are about general old hardware.

I'm going to guess you've not even used the chip.

The POD is a yummy chip which is even better at 100mhz.

Reply 14 of 14, by OSkar000

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Thanks for the help everyone. This system is not about being the fastest and most optimized Socket 3 system at all. Its more about filling an old full tower with missmatching hardware from the middle of the 90is and making a fun and cool system that can be used for many things. It will have lots of harddrives, SCSI and good sound and networking.

And I have one really good reason to have the POD in this system... 😀

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One of the nicest two-digit displays I have ever seen!

End of discussion 😁