You could get one of these toggle switches to replace the one in the adapter you have and mount it to the back of the case. Or just try to get an AT case.

PhilsComputerLab wrote:

A 486 is always something special 😀

For the power switches, in the end I used one of these 3.5" to 5.25" bay devices. On the sides there is some space and I just drilled two holes and put switches in. One for power, one for turbo 😊

You can do the same thing with a read slot cover, but then you got to reach around. Still works well.

Going to go really old school for my at to atx conversions and have the switch in the back 😎
Just feels more real that way 😉

You could also use a turbo button which is simply a toggle button, and swap out the momentary power button since they are the same design.

Brickpad wrote:

You could also use a turbo button which is simply a toggle button, and swap out the momentary power button since they are the same design.

Couldn't I just plug the case's power button jumper into the motherboard turbo header? Then the front power switch becomes the turbo switch. I could mount the power switch on my adapter out the back of the case. That will do in a pinch, while I keep my feelers out for a proper case with turbo LED. (I've got a contact who probably has one among a treasure trove of retro gear, but I have to wait til he has time and invites me to his storage facility).

clueless1 wrote:

Couldn't I just plug the case's power button jumper into the motherboard turbo header?

If the button is of the latching type then yes, otherwise (i.e. if it's momentary only) no.

clueless1 wrote:

Then the front power switch becomes the turbo switch.

Or you just ignore the Turbo button for now until you get a proper AT case 😀 It's possible that your motherboard doesn't even provide actual Turbo functionality, or that you will really need it. I have a PCI 486 motherboard that completely ignores the turbo button, but I still have it connected for the coolness factor 😎

Ah, I thought only the power button required a physical switch. Since the turbo button has a motherboard header, I thought the newer ATX-case switches would work on it. Would it hurt the board to try?

My interest in the turbo button is for benchmarking purposes. 😀

clueless1 wrote:

Ah, I thought only the power button required a physical switch. Since the turbo button has a motherboard header, I thought the newer ATX-case switches would work on it. Would it hurt the board to try?

Nope. The worst that can happen is that it only gets enabled for a fraction of a second, or you'll have to hold down your finger on the button to keep it activated.

Here's what the BIOS screens look like. Any suggestions for altering any of the existing settings?

Looks good! Maybe enable a bit more Shadow Memory. Perhaps it can then be used by HiRAM. Depends on the chipset..

Jo22 wrote:

Looks good! Maybe enable a bit more Shadow Memory. Perhaps it can then be used by HiRAM. Depends on the chipset..

Just out of quriosity. Does this have any relationship to EMM386?
I have noticed that on some motherboards, you get an frozen system, when using the line "DEVICE=C:\DOS\EMM386.EXE RAM HIGHSCAN".

While I wait for the I/O controller, I'm testing a couple of hdds that are candidates for this 486 system:
8.4GB Fujitsu MPE3084AE
1.0GB Seagate ST51080A

The Fujitsu has 85 bad sectors and 7.4 years of power on time (64998 POH). It passes all maintenance tests (even SpinRite Level 4) I throw at it except for POH (linux smartmontools fails it automatically if it's over 5 years). Performance (in a modern system):

The Seagate does not support SMART, so I can't glean POH or any reliability data from it. However, it passes SeaTools Long Test with flying colors, as well as SpinRite level 4 scans. Here's its performance profile in a modern system:

Without knowing the POH on the Seagate, nor knowing if it's ever had any bad sectors, it's a tough call. I tend to go with the Seagate because it is closer to period correct, being a 1995 drive. The Fujitsu was mfg in 2000.

Plus, the I/O on this system will be the bottleneck for both drives, so other than access time, the two drives should perform similarly.

Fun stuff. 😀

clueless1 wrote:

Without knowing the POH on the Seagate, nor knowing if it's ever had any bad sectors, it's a tough call. I tend to go with the Seagate because it is closer to period correct, being a 1995 drive. The Fujitsu was mfg in 2000.

I don't think you'll use this system for mission critical applications, so use whatever feels better 😀

clueless1 wrote:

Plus, the I/O on this system will be the bottleneck for both drives, so other than access time, the two drives should perform similarly.

I don't think it's possible to transfer more than 5MB/s over ISA, but even VLB controllers seem to offer only marginal improvements over that. If you want a "fast" 486 the only option is getting a PCI motherboard and a CF card. If you want period correctness, the Seagate will do fine, and by fine I mean be just as slow as it was back then 🤣

devius wrote:

I don't think it's possible to transfer more than 5MB/s over ISA, but even VLB controllers seem to offer only marginal improvements over that. If you want a "fast" 486 the only option is getting a PCI motherboard and a CF card. If you want period correctness, the Seagate will do fine, and by fine I mean be just as slow as it was back then 🤣

Nah. It only feels slow now because we know what fast is. Back then, we had a different definition of fast. 😉

DOS games are about as mission critical as my data gets!

clueless1 wrote:

It only feels slow now because we know what fast is. Back then, we had a different definition of fast. 😉

Speak for yourself 😜 I always hated mechanical HDDs because of how slow they were, even when I had a 486 and it was "normal", it still felt slow to me and it bothered me having to wait for the HDD to finish. IIRC my HDD of the time was able to transfer at a max of 2.6MB/s 😒

brostenen wrote:

Jo22 wrote:

Looks good! Maybe enable a bit more Shadow Memory. Perhaps it can then be used by HiRAM. Depends on the chipset..

Just out of quriosity. Does this have any relationship to EMM386?
I have noticed that on some motherboards, you get an frozen system, when using the line "DEVICE=C:\DOS\EMM386.EXE RAM HIGHSCAN".

Well, yes and no. By enabling Shadow Memory, you can "flood" a specific region with RAM.
This can be handy to copy the system's BIOS, the VGA BIOS or any other firmware from ROM chip into the faster RAM (your BIOS has separate settings for that).
However, EMM386 doesn't need that to work. It uses the Memory Managment Unit (MMU) to map extended memory into the Upper Memory Area (UMA)
and creates upper memory blocks which DOS can use (UMBs). And it also provides EMS if you wish.
This works fine most of the time, but EMM386 also switches the processor into V86 mode.
And EMM386 also requires some memory for itself and it is stressing 386/486 chips a bit.

Alternatively, you can also have UMBs without EMM386 loaded.
If Shadow Memory is enabled, you basically have UMBs in "hardware".
However, there's a drawback: The memory is still write-protected.
By using a special chipset driver or the "HiRAM" package you can make it writable.
These drivers also have another function: They mark these UMBs as "free", so these regions of memory can bee seen and used by DOS.

Or in other words: It's similar to UMBPCI, just for older machines (286-486) without PCI. ^^

I hope you understand what I mean. I'm a bit tired today and my wording is poor.
And maybe some of the things I said are aren't entirely right, dunno.

While I wait for the I/O card, I thought it would be fun to play "dress up" with my 486. 🤣. Stealth Mode...Engage!

I will probably move it back to the beige case, but wanted to see how the 486 looked in black.

Jo22 wrote:

Well, yes and no. By enabling Shadow Memory, you can "flood" a specific region with RAM. This can be handy to copy the system's […]
Show full quote

brostenen wrote:

Jo22 wrote:

Looks good! Maybe enable a bit more Shadow Memory. Perhaps it can then be used by HiRAM. Depends on the chipset..

Just out of quriosity. Does this have any relationship to EMM386?
I have noticed that on some motherboards, you get an frozen system, when using the line "DEVICE=C:\DOS\EMM386.EXE RAM HIGHSCAN".

Well, yes and no. By enabling Shadow Memory, you can "flood" a specific region with RAM.
This can be handy to copy the system's BIOS, the VGA BIOS or any other firmware from ROM chip into the faster RAM (your BIOS has separate settings for that).
However, EMM386 doesn't need that to work. It uses the Memory Managment Unit (MMU) to map extended memory into the Upper Memory Area (UMA)
and creates upper memory blocks which DOS can use (UMBs). And it also provides EMS if you wish.
This works fine most of the time, but EMM386 also switches the processor into V86 mode.
And EMM386 also requires some memory for itself and it is stressing 386/486 chips a bit.

Alternatively, you can also have UMBs without EMM386 loaded.
If Shadow Memory is enabled, you basically have UMBs in "hardware".
However, there's a drawback: The memory is still write-protected.
By using a special chipset driver or the "HiRAM" package you can make it writable.
These drivers also have another function: They mark these UMBs as "free", so these regions of memory can bee seen and used by DOS.

Or in other words: It's similar to UMBPCI, just for older machines (286-486) without PCI. ^^

I hope you understand what I mean. I'm a bit tired today and my wording is poor.
And maybe some of the things I said are aren't entirely right, dunno.

Thanks for the clearup. 😀

clueless1 wrote:

While I wait for the I/O card, I thought it would be fun to play "dress up" with my 486. 🤣. Stealth Mode...Engage!

black.jpg

I will probably move it back to the beige case, but wanted to see how the 486 looked in black.

It actually does not look bad. All you need now, is to blank out that empty space were the ATX shield goes.

clueless1 wrote:

While I wait for the I/O card, I thought it would be fun to play "dress up" with my 486. 🤣. Stealth Mode...Engage!

I will probably move it back to the beige case, but wanted to see how the 486 looked in black.

Looks very nice. Black CRT too...

I've been meaning to ask, was it fairly common for BIOS chips to block ISA slots? It seems all my ISA cards will not seat fully in slots 2 and 3 because of the AMIBIOS chip there.