VOGONS


First post, by PhilsComputerLab

User metadata
Rank l33t++
Rank
l33t++

Video build log: Building a 486 with modern parts

So you want to build a 486? That's awesome! You can get yourself a ready to go 486, all authentic with that retro AT case and whizzing hard-drive, but as vintage parts fail, or become harder and more expensive to obtain, maybe you have thought of combining a 486 with more modern parts to save money, improve reliability, or have a machine that blends in with others, but under the hood retro goodness awaits you!

In this project we are building a 486 retro DOS PC but using modern parts such as:

ATX case
ATX power supply
CF card as HDD replacement
GOTEK floppy emulator as FDD replacement
New buttons for power and turbo

I did run into some roadblocks, but that's good, it means you will avoid these mistakes and have a smoother project! Specifically the replacements budgets turned out to be garbage and I didn't end up mounting them to the front of the case, but that is all explained in the video.

The case is a standard, cheap and nasty, ATX case from Aywun:

ZR4AFsDl.jpg

I'm using this ATX to AT adapter:

Z3ayJRPl.jpg

CF card reader:

WIOeDBJl.jpg

Floppy emulator:

4T8RpJwl.jpg

This is the type of button I used:

pQGD0cJm.jpg

The computer specifications:

Biostar MB8433-UUD motherboard
IntelDX4 100 MHz processor
8 MB of RAM
PCI S3 Trio 64 V+ graphics card
2 GB CF card
IDE optical drive,
Sound Blaster 16
World exclusive: the prototype of the DreamBlaster X1 General MIDI wavetable board
MS-DOS 6.22

Findings:

The build was quite straight forward. The trickiest part is the new power and turbo buttons, I found some alternatives since producing this video:

You can use a 5.25" to 2.5" adapter and it has some space on the sides. Ideal for mounting switches or buttons.

You can mount switches or buttons onto spare slot covers. Just means you need to reach around the computer to turn it on/off or use the turbo feature.

YouTube, Facebook, Website

Reply 2 of 17, by PhilsComputerLab

User metadata
Rank l33t++
Rank
l33t++
sprcorreia wrote:

Just watched the video. It's a good one. But were you running the CPU without a heatsink all the time?

Yes 😊

YouTube, Facebook, Website

Reply 3 of 17, by Imperious

User metadata
Rank Oldbie
Rank
Oldbie

Thanks for the Vid Phil, enjoyed it a lot.

I would suggest drilling a hole in the rear of the Case for the Turbo switch, it's not like Your going to be turning it on and off a lot. I was going to do a similar
thing with my 486 mobo but ended up getting a Super socket 7 computer in an AT case for $20 from Gumtree. I was going to put the Turbo in the rear but
obviously no need now.
I have run my DX2-66 and also AMD 5x86-133 with out a heatsink no problems, but have purchased some heatsinks and 3M double sided thermal adhesive
to rectify the lack of cooling.

Atari 2600, TI994a, Vic20, c64, ZX Spectrum 128, Amstrad CPC464, Atari 65XE, Commodore Plus/4, Amiga 500
PC's from XT 8088, 486, Pentium MMX, K6, Athlon, P3, P4, 775, to current Ryzen 5600x.

Reply 4 of 17, by PhilsComputerLab

User metadata
Rank l33t++
Rank
l33t++

I agree. A 386 is very specialised / limited. A 486 can do what a 386 can do and more. A Socket 7 machine can do what a 386 can do, as well as a 486 and more 😀

But it was time to play with some of my older gear, so I just had to do it.

I like the idea of buttons at the back. You can mount one through a rear slot bracket, that works well.

YouTube, Facebook, Website

Reply 5 of 17, by alexanrs

User metadata
Rank l33t
Rank
l33t

I thought about doing so with my 8088, but the fact that the length of new ATX cases is somewhat non-standard would cause trouble with a full-length CGA card. I'm thinking about moving another AT system into a modern case.

Reply 7 of 17, by PhilsComputerLab

User metadata
Rank l33t++
Rank
l33t++
smeezekitty wrote:

Awesome case. But seriously, what's up with the 8MB of RAM? That's barely enough to run Windows 95

It's running MS-DOS 6.22.

YouTube, Facebook, Website

Reply 9 of 17, by PhilsComputerLab

User metadata
Rank l33t++
Rank
l33t++
8086-ProGamer wrote:

Nice!

I bought this CF Card reader today. How do i set Master/Slave, is it the jumper on the reader?

Yes!

YouTube, Facebook, Website

Reply 10 of 17, by smeezekitty

User metadata
Rank Oldbie
Rank
Oldbie
philscomputerlab wrote:
smeezekitty wrote:

Awesome case. But seriously, what's up with the 8MB of RAM? That's barely enough to run Windows 95

It's running MS-DOS 6.22.

Even so, CF cards makes it easy to switch OSes so it would make sense to build the hardware for such. More RAM never hurts, even in DOS either.

Reply 11 of 17, by carlostex

User metadata
Rank l33t
Rank
l33t
philscomputerlab wrote:

(...)A Socket 7 machine can do what a 386 can do, as well as a 486 and more 😀

True for the faster speeds, but a 486 is probably easier to deturbo, if you consider the greater number of boards with voltage regulators that supported ultra low FSB settings.

Some socket 7 motherboards do too, but are much more the exception rather than the rule. Plus, Socket 7 boards are less tolerant to lower FSB speeds. Some 486 motherboards can run as low as 2MHz. I have suggested a hardware mod to a Socket 7 motherboard, that apparently seems to overcome the issue of running 7MHz FSB.

I suspect that a K6-III+ running at 14MHz with caches disabled could be very much be as slow as a low clocked 286.

Reply 12 of 17, by PhilsComputerLab

User metadata
Rank l33t++
Rank
l33t++

With a MMX and L1 disabled (L2 enabled), you get ~ 486DX250 - 66. That's as fast as you can go though. I could have done benchmarks with cache tricks and turbo, but the focus of the video was building the machine and showing alternatives.

YouTube, Facebook, Website

Reply 13 of 17, by 8086-ProGamer

User metadata
Rank Newbie
Rank
Newbie
philscomputerlab wrote:
8086-ProGamer wrote:

Nice!

I bought this CF Card reader today. How do i set Master/Slave, is it the jumper on the reader?

Yes!

Thanks!
1 question, when installing a CF card, is it better to use it as a SSD, no use of Defrag software, or maybe Scandisk etc.?

Sorry for my bad English 😊

Reply 14 of 17, by PhilsComputerLab

User metadata
Rank l33t++
Rank
l33t++

Hmm. Good question. I think that it's not necessary / recommended to defrag a CF card.

YouTube, Facebook, Website

Reply 15 of 17, by alexanrs

User metadata
Rank l33t
Rank
l33t

AFAIK you should avoid defrags as CF cards are flash memory that does not suffer from slow random access speed, and defragmenting uses too many write cycles for no benefit.

Reply 17 of 17, by PhilsComputerLab

User metadata
Rank l33t++
Rank
l33t++

Ordered a 486 CPU cooler 😊

http://www.ebay.com.au/itm/331625552155?_trks … K%3AMEBIDX%3AIT

YouTube, Facebook, Website