486 Overdrive upgrade - Any experience?

[OVERKILL]

486DX475 (25Mhz FSB still):

Had to buy an EPROM programmer (TL866-3G) to program a BIOS chip for it, since there's a known bug with the DX4 ODP's and this computer where the L1 cache gets completely disabled and it performs like this:

That arrived today. The difference is STARK.

Then, I threw caution to the wind and decided to do the resistor mod. Unsoldered R176 and bridged the contacts for 174 and 175, didn't use resistors as Thermalwrong on Vogons was confident they were just used due to the machine assembling the board. SUCCESS!! 486 DX4-100 action now:

Also have the VRAM upgrade installed, so it has 1MB of video RAM (posted in the pics thread). With the DX4 100 it gets 29.43FPS in the Doom high graphics test, which is completely playable.

 

[BaronHK]

Before the parts start arriving, baseline benchmark results!
View attachment 260340


Also found Duke Nukem 3D and Hexen on CD, so going to install those. I've currently got WIndows 95C on it (yes, I've changed OS direction several times now), as that's what was on the hard drive.

I think C had IE 3, but you could delete ohare.inf and ohare.cab or something from the setup directory and it would skip over that.

I found various ways to completely remove IE+crap from Windows 9x. My advice would be 98 SE, which you can use RoM II SE on if you have the shell files it needs from the OEM service releases of Windows 95 (OSR 2.1 was what I used), because this will get rid of the Active Desktop code which won't work without Trident.

Then there's the "icon fix" utility you have to use, but that's a nit.

In exchange you can then install KernelEx, DirectX 9.0c up to March 2006, and a bunch of other things.

I reverted some systems that came with Windows XP and Pentium 4s (non-HT though, which is just as well since 98 can't handle that).

Intel set the installer for the chipset drivers to say it was incompatible with Windows 98, but dumping the setup file and right clicking and installing the INF file installed the WDM stuff into Windows 98 and it all came right back up, and Nvidia had 98 drivers for that card.

Then I took defrag.exe and notepad.exe out of Windows Me and stomped the ones from Windows 98, to get defrag to stop saying "Drive contents changed, restarting." and to bust the file size limit Notepad had.

Windows 98's kernel had an improved memory manager that could run code that was in the vcache area, where Windows 95 had to lower the vcache because you couldn't cache from the disk to that point and do anything else on it, it was just a disk cache, so far less useful and a waste of RAM.

Microsoft extended Windows 95 in OEM only releases, but didn't want to release it to wider channels. Its limits, like FAT16, were getting painful and embarrassing, but it didn't want to give users enough that they would opt out of Internet Explorer being everywhere in 98. Touching almost everything, like a tumor.

RoM II SE readme and files.

Windows 98 will work better than 95, once IE is gone and you've backported the redists and kernelex.

I recall that most of my games on a K6/2 550 with 128 MB RAM and 3dfx Voodoo 2 averaged another 1-2 frames per second after the purge, so if all the extra gunk slowed down that, I can only imagine what it would do to a 486 overdrive.

Relieved of its bulk, Windows 98 also got a lot more stable. I could frequently run it for months, or even over a year once without rebooting it or getting a BSoD.

Bill Gates basically perjured himself when he claimed IE was integrated so deeply that it disappeared into the OS and removing it was impossible. It was more tightly integrated into Windows XP and later than it ever was into 9x. Professor Felton demonstrated during the trial that removing IE was relatively simple.

 

[OVERKILL]

I think C had IE 3, but you could delete ohare.inf and ohare.cab or something from the setup directory and it would skip over that.

I found various ways to completely remove IE+crap from Windows 9x. My advice would be 98 SE, which you can use RoM II SE on if you have the shell files it needs from the OEM service releases of Windows 95 (OSR 2.1 was what I used), because this will get rid of the Active Desktop code which won't work without Trident.

Then there's the "icon fix" utility you have to use, but that's a nit.

In exchange you can then install KernelEx, DirectX 9.0c up to March 2006, and a bunch of other things.

I reverted some systems that came with Windows XP and Pentium 4s (non-HT though, which is just as well since 98 can't handle that).

Intel set the installer for the chipset drivers to say it was incompatible with Windows 98, but dumping the setup file and right clicking and installing the INF file installed the WDM stuff into Windows 98 and it all came right back up, and Nvidia had 98 drivers for that card.

Then I took defrag.exe and notepad.exe out of Windows Me and stomped the ones from Windows 98, to get defrag to stop saying "Drive contents changed, restarting." and to bust the file size limit Notepad had.

Windows 98's kernel had an improved memory manager that could run code that was in the vcache area, where Windows 95 had to lower the vcache because you couldn't cache from the disk to that point and do anything else on it, it was just a disk cache, so far less useful and a waste of RAM.

Microsoft extended Windows 95 in OEM only releases, but didn't want to release it to wider channels. Its limits, like FAT16, were getting painful and embarrassing, but it didn't want to give users enough that they would opt out of Internet Explorer being everywhere in 98. Touching almost everything, like a tumor.

RoM II SE readme and files.

Windows 98 will work better than 95, once IE is gone and you've backported the redists and kernelex.

I recall that most of my games on a K6/2 550 with 128 MB RAM and 3dfx Voodoo 2 averaged another 1-2 frames per second after the purge, so if all the extra gunk slowed down that, I can only imagine what it would do to a 486 overdrive.

Relieved of its bulk, Windows 98 also got a lot more stable. I could frequently run it for months, or even over a year once without rebooting it or getting a BSoD.

Bill Gates basically perjured himself when he claimed IE was integrated so deeply that it disappeared into the OS and removing it was impossible. It was more tightly integrated into Windows XP and later than it ever was into 9x. Professor Felton demonstrated during the trial that removing IE was relatively simple.

Since this computer is more for nostalgia (and playing DOS games) than any real use, and doesn't have an internet connection, I'm not overly concerned about using IE. In fact, I enjoy the updated explorer experience vs native. I've also installed Plus! now, to get the High Colour themes and icons.

I try to make each of these systems relatively "authentic" (though I think I may have deviated from that with modding this mobo to get a 33Mhz fsb), which means period correct OS's relative to their hardware.

Amusingly, I was on the Windows 98 Beta Team, and have my original release (CD specific to Beta testers) around here somewhere. It was on this computer, with 24MB of RAM, the same hard drive that is in it currently, a Trident 1MB ISA video card and its original 486 SX/25 glory, that I participated. Oh, the number of wipes and reloads with various OS's this old girl had over the years, it was glorious. It's run FreeBSD, NetBSD, OpenBSD, Slackware, Redhat, Windows 3.11, 95, 98, 98SE, BeOS, NT4 and probably a few others I'm forgetting.

 

[OVERKILL]

If you check on vogons it was discovered on most IBM 486sx systems that there are small resistors soldered to the board where the FSB jumpers would normally be.

If you bridge/unbridge certain resistors you get different FSBs, some boards are stable at 40mhz FSB .

There is also an open source interposer project you can can regulate and jumper the 4x multiplier on 5x86 CPUS (AMD/Cyrix)

A few have used a socket extension to install a p24t to the board leaving the extra pins hanging

Good luck

Want to thank you for this suggestion, the further I got into this, the more it made sense to do the FSB mod for 33Mhz.

 

[blufeb95]

Some boards also used fixed crystals, usually you'd find a 50mhz crystal on a 25mhz bus board, if that's the case you could try replacing it with a 66mhz crystal, but if there's no way to change the ISA divider that could be a problem.

 

[OVERKILL]

Some boards also used fixed crystals, usually you'd find a 50mhz crystal on a 25mhz bus board, if that's the case you could try replacing it with a 66mhz crystal, but if there's no way to change the ISA divider that could be a problem.

Yes, in this case IBM didn't, they used the same parts and the same board for CPU's with both 25 and 33Mhz FSB's (and it could also do 40Mhz), some systems even had dip switches to select between them, but most of them were hard wired for one or the other through the use of resistors between the paths and ground. This was discovered on Vogons when comparisons were made between a 33Mhz board and a 25Mhz one and the difference was just which paths were open vs which were bridged with a small resistor, allowing them to go to ground.

Amusingly, this mod wouldn't have worked for me back in 95 or 96, because I didn't have access to the "TOM 1.0" BIOS that unlocked the cache. The machine would have worked, but it would have been slower than with the SX25 (as the benchmarks posted show). Mind you, I probably would have gone with the "approved" overdrive back then, which was the DX2-50.

 

[Kruse]

Since this computer is more for nostalgia (and playing DOS games) than any real use, and doesn't have an internet connection, I'm not overly concerned about using IE.

Time to load up 'Johnny Castaway" and just use it as a conversation piece when you throw a party.

 

[OVERKILL]

This has become quite the rabbit hole!

I've discovered XT-IDE, which, in its cheapest form, allows me to flash a ROM onto a DIP28 and place it in the PXE boot socket on my 3C509 NIC and use it instead of drive overlay software (Ontrack currently) so I can use larger hard drives. Since I already bought a ROM programmer to flash the "TOM 1.0" BIOS so I could use a DX4 CPU, I've ordered an EEPROM and will be going this route. I have an SD card adapter already for it, but my WD 1600 does NOT like USB adapters (doesn't show up) so I'm trying to figure out how I'll clone my Windows 95 install from the WD to an SD card.

Goal is now to have multiple OS's on SD cards:
1. Windows 95C/DOS - Gaming
2. Windows NT4 SP6 - Why not?
3. OS/2 - Also a "why not"

May also try Linux and FreeBSD, as this thing was always slow with the SX25, but it flies with the DX4-100.

 

[blufeb95]

This has become quite the rabbit hole!

I've discovered XT-IDE, which, in its cheapest form, allows me to flash a ROM onto a DIP28 and place it in the PXE boot socket on my 3C509 NIC and use it instead of drive overlay software (Ontrack currently) so I can use larger hard drives. Since I already bought a ROM programmer to flash the "TOM 1.0" BIOS so I could use a DX4 CPU, I've ordered an EEPROM and will be going this route. I have an SD card adapter already for it, but my WD 1600 does NOT like USB adapters (doesn't show up) so I'm trying to figure out how I'll clone my Windows 95 install from the WD to an SD card.

Goal is now to have multiple OS's on SD cards:
1. Windows 95C/DOS - Gaming
2. Windows NT4 SP6 - Why not?
3. OS/2 - Also a "why not"

May also try Linux and FreeBSD, as this thing was always slow with the SX25, but it flies with the DX4-100.

For 9x, I've always been a fan of using 98LITE Micro, I use Windows 98SE and use the Windows 95 OSR2 w/o IE explorer and shell files. The lightweight experience of Windows 95 without IE with the added stability of Windows 98.

 

[JHZR2]

Before the parts start arriving, baseline benchmark results!
View attachment 260340


Also found Duke Nukem 3D and Hexen on CD, so going to install those. I've currently got WIndows 95C on it (yes, I've changed OS direction several times now), as that's what was on the hard drive.

I love those old benchmarks. I had an AMD K6-III processor or with the L3 cache. I was a first Athlon user too, a big fan of the 18u athlons starting with the 750MHz. My how times have changed.

Thanks for the blasts from the past!

 

[blufeb95]

I love those old benchmarks. I had an AMD K6-III processor or with the L3 cache. I was a first Athlon user too, a big fan of the 18u athlons starting with the 750MHz. My how times have changed.

Thanks for the blasts from the past!

I still have a great fondness for the AXP and A64 era, the first computer I got that was my own was an AXP 2400+, then I really wanted an A64 when AMD was on top for a few years before the Core2 era.

 

[OVERKILL]

I still have a great fondness for the AXP and A64 era, the first computer I got that was my own was an AXP 2400+, then I really wanted an A64 when AMD was on top for a few years before the Core2 era.

I'm going to eventually be looking for a Slot A Athlon and a board with the AMD chipset at the time (much better than the SiS, VIA and ALI offerings).

 

[JHZR2]

I'm going to eventually be looking for a Slot A Athlon and a board with the AMD chipset at the time (much better than the SiS, VIA and ALI offerings).

Yes! 750Mhz 18u for the win! I think I picked an MSInmotherboard to get the fastest benchmarked AMD chipset iirc. IBM deskstar HD was it? Those were the days!

Or was it 550MHz processors made on 18u 750MHz declocked cores?? Maybe that’s what I had.

 

[OVERKILL]

Yes! 750Mhz 18u for the win! I think I picked an MSInmotherboard to get the fastest benchmarked AMD chipset iirc. IBM deskstar HD was it? Those were the days!

Or was it 550MHz processors made on 18u 750MHz declocked cores?? Maybe that’s what I had.

Athlon Slot A 800Mhz!

And you can apparently buy "new" FIC AMD 750 chipset motherboards:
https://www.ebay.ca/itm/28552924871...zxpEwuV43Pgj1P9UfxUKRqmQ==|tkp:Bk9SR7KFmaWgZQ

 

[JHZR2]

Athlon Slot A 800Mhz!
View attachment 263379

And you can apparently buy "new" FIC AMD 750 chipset motherboards:
https://www.ebay.ca/itm/28552924871...zxpEwuV43Pgj1P9UfxUKRqmQ==|tkp:Bk9SR7KFmaWgZQ

That’s an 18um there. It’s the one you want.

 

[OVERKILL]

That’s an 18um there. It’s the one you want.

My next project arrived! (233 MMX). Once I confirm this old CPU/Mobo combo works, I have to find a case for it.

 

[JHZR2]

My next project arrived! (233 MMX). Once I confirm this old CPU/Mobo combo works, I have to find a case for it.
View attachment 263460

I think that was my first PC. Grew up on Apple IIe and early Mac.

Mine was in a Packard Bell tower. Weird setup, I think the processor and the ISA slots were on a riser board. The motherboard was like an upside down T.

 

[OVERKILL]

I think that was my first PC. Grew up on Apple IIe and early Mac.

Mine was in a Packard Bell tower. Weird setup, I think the processor and the ISA slots were on a riser board. The motherboard was like an upside down T.

New thread incoming! My Jetway board apparently doesn't like the 233, but works fine with the old Pentium 75 I scored. Was concerned that the 233 was DOA, so I ordered another motherboard, it showed up today and the 233 is G2G, and the new board has AGP!

 

[JHZR2]

New thread incoming! My Jetway board apparently doesn't like the 233, but works fine with the old Pentium 75 I scored. Was concerned that the 233 was DOA, so I ordered another motherboard, it showed up today and the 233 is G2G, and the new board has AGP!

Did the old board have a fast enough fsb to jumper to a 233?

 

[Bottom_Feeder]

New thread incoming! My Jetway board apparently doesn't like the 233, but works fine with the old Pentium 75 I scored. Was concerned that the 233 was DOA, so I ordered another motherboard, it showed up today and the 233 is G2G, and the new board has AGP!

Socket 5 vs Socket 7?