Jump to content
DonutKing

Blast from the Past - 486DX2 system

Recommended Posts

Having been reading a lot of retro threads over at OCAU and VOGONS I was inspired to build a dos box for old games... to recapture some of my mispent youth :P

I used to have quite a stockpile of old parts around the turn of the century, because I used to play around with these old PC's a lot back then, however a quick trip to my shed showed that most of them had been thrown away :(

After a bit of scrounging for parts I've finally got everything going :)

 

I decided to go for a 486DX2. The 486 is interesting for a couple of reasons- the 486DX was the first Intel CPU to include a maths coprocessor (aka Floating Point Unit) inside the CPU. The 486SX did not include the maths coprocessor, (or it was there but disabled) which was its only difference.

The 486DX2 was also the first Intel CPU to be clock multipled- that is, running at a multiple of the speed of the motherboard. In the case of the DX2 it was double, for the DX4 it was triple (just to be confusing). modern processors often run at 10x-20x clock multiples.

 

The 486 also included 8kb of on-die L1 cache; another first for Intel processors. (The DX4 upped this to 16kb). This was in addition to the cache that was installed on the motherboard- a practice that became popular with the 386. This motherboard cache became L2 cache, and has basically disappeared since the days of the Pentium Pro and Pentium 2 which included L2 cache in the processor, as has nearly all modern processors since.

 

There were also a variety of processors you could run in a 486 board- Cyrix and AMD both had their 486 variants but there were also 586 processors available at speeds up to 133MHz. Early 486 CPU's ran at 5 volts and later ones, especially 586's ran around 3.3 volts so you had to get a voltage regulator if your motherboard didn't support it. You could even get Pentium Overdrive processors to fit in your 486 board, some of which included voltage regulators so they'd fit in older 5v only boards.

 

Finally, there was the VESA Local Bus (VLB), a type of expansion card slot that was pretty much exclusive to the 486 (There were apparently some Pentium boards that supported VLB but were quite rare- VLB lost popularity to the PCI bus around the time the Pentium became common). The VLB slot is a standard 16bit ISA slot with what looks like a PCI conector on the end; this made for very long expansion cards. (Not as long as full-length cards from the eighties though). VLB didn't like going above 33-40MHz which was probably one of the driving factors behind the clock-multipled CPU's like the DX2.

 

Anyway, on to the build. I had a few boxes of parts in my shed but I was missing some important parts- mainly a case and motherboard.

Fortunately the local tip shop had a few AT machines for about $5 each; this one was in exceptional condition so I chose it to house my system. A quick cleanup and it was almost like new:

Posted Image

 

Opened the PSU and gave it a quick cleanup too, wasn't too dirty for its age. Checked all the voltages with a multimeter and everything seemed ok.

 

These old style PSU's are a bit different to modern ATX units...

Posted Image

 

The connector on the top left has an extra wire to power the LED speed display on the front of the case. It alternates between LO/HI if the turbo button is off or on. Some of these displays can be configured to say whatever you like via jumpers; this one isn't configurable.

In the middle are the two motherboard power leads. Unlike ATX power plugs, these are physically different connectors, and you must also take great care to plug them in correctly- the rule is black wires go together. If you get them backwards you will smoke the board.

On the right is the pwoer switch. Back in the early days the power switch was located on the back of the PC so you had to reach around the back to turn the machine on. This was eventually moved to the front of the case for greater usability but instead of using a simple relay or something they simply moved the whole 240v mains power switch... so these power switches are live, and you have a wire carrying 240v snaking through your PC. I have been bitten by one of these switches before and it wasn't much fun... Thankfully ATX changed the power switch to a 5v soft-power button, which was much safer and allowed the pc to be powered on and off by software.

 

Anyway, now I needed to track down a VLB motherboard- luckily I found a Shuttle HOT407 on Ebay, unused, still in original packaging, for about $25. Also had 256kb of onboard cache, in sockets. This is important because fake cache boards were not uncommon in this era; the general rule of thumb is if the chips are soldered rather than socketed, and they say WRITE BACK or similiar in big letters on the chips, they are usually fake. The main culprit for this was PC CHIPS however they had a number of different aliases and their boards often did not carry any identifying information. Back in the 386/486 days you often had some cache installed on the motherboard in sockets (so it could be replaced in case of failure). The 386 had no onboard cache so the motherboard's cache was in effect L1, the 486 and later processors all had L1 integrated into the CPU so the motherboard's cache was L2. The socket 7 Pentium era boards usually had a couple of L2 cache chips soldered on to the board, or had a slot for a COAST module (Cache on a stick- basically looked a bit like a stick of RAM that went into a special slot). After the Pentium Pro and Pentium 2 came out with L1 and L2 cache integrated into the processor package, the practice of installing cache on desktop motherboards ceased.

 

So I placed a bid on the HOT407, snapped it up and within 2 weeks I had it in my hot little hands:

Posted Image

Posted Image

This is what you get when you buy a new 486 motherboard- bundle is a bit tight compared to todays boards :P A manual and a utility floppy disk.

 

I eagerly stuffed a processor and a couple of sticks of 72-pin RAM into the board. Hit the power and.... nothing. Damn. Dead board? Its possible, if its been sitting in a box on a shelf for 15 years I guess. Quick check of the manual and they said they supported 36 bit wide SIMMs. Something clicked and I remembered that means parity- basically the precursor to modern ECC RAM. So this board needed parity SIMMs. I had a stack here to go through but the general rule of thumb is an odd number of chips on each stick- because a byte has an even number of bits, and 72-pin SIMMs were 32 bits wide (4 bytes), while parity added an extra bit to each byte making 36 bits wide. Non-parity SIMMs would usually have 2, 4 or 8 chips to hold the data and Parity SIMMs would have one extra chip to calculate the parity bit for each byte of data.

 

I ended up using 2 8MB SIMMs for a total of 16MB, in the era this would have been extravagantly expensive (especially with parity), most machines like this came with 4x2MB SIMMs for 8MB.

 

Anyway, once I found a pair of parity SIMMs the board booted without issue.

Except that the CMOS battery was dead- fair enough for a 15 year old battery.

Posted Image

 

It was one of those barrel batteries that was soldered to the board. Luckily it hadn't leaked or corroded anything so I could simply remove it, and plug in an external battery and all should be well.

So I whipped out the soldering iron and pulled off the old battery:

Posted Image

 

Plugged in an external battery pack from Jaycar and it was happy :) I've seen a few of these barrel type batteries leak and corrode boards so I'm not a fan of them. I've also seen external batteries leak too so its important to locate them somewhere where they won't leak onto anything important.

 

At this point I swapped from the standard DX2 to the overdrive model, purely because it had an integrated heatsink and the CPU was getting very hot to the touch:

Posted Image

 

As far as I'm aware, the DX2 Overdrive is identical to the standard DX2, (apart from the heatsink) but all the retail boxed DX2 CPU's were Overdrive models.

(I actually still have a boxed DX2 Overdrive processor still in the shrink wrap- not going to open it though :)

 

 

 

Now for other components. I had a box of VLB cards and I had to go through a few before I decided which ones to use.

 

Posted Image

 

The top card is a Winbond IDE/IO controller card. Back then motherboards did not have IDE or floppy controllers built in, you needed to install a controller card for these.

Some later 486 boards and most Pentium boards included them onboard, as have nearly all boards since.

 

I had to go through about 6 of these before finding one that worked properly. One would read the hard disk but would fall over as soon as you tried to write to it...

This particular one worked fine, and even had the jumper settings silkscreened on the back. :)

 

The bottom card is an S3 805 video card. In my testing with 3dbench and PCPBench this card was one of the fastest that I had compared to various Cirrus Logic and WDC cards. Notice the empty sockets on the card; back then you could upgrade your video card's memory instead of buying a whole new card. This one already included a whopping 1MB which was fine for my purposes.

 

Now a sound card- a Creative Sound Blaster 16

Posted Image

 

This one is an ealier, non- PnP model so its IRQ/DMA settings are configured by jumpers rather than software- which is what I preferred as I wasn't going to need to fiddle with it once its installed. It also means less software to load when your computer boots.

Notice the connector on the left edge- its a proprietary interface for a Panasonic (I think) CD ROM drive. Before CDROM drives started using the IDE standard you needed a CDROM controller card to connect them to. Often different companies had different interfaces which were incompatible with each other. This one has a few less pins than an IDE connector too. Often, sound cards would include a CDROM controller onboard- you could get them for different CDROM drives- Sony, Panasonic, Mitsumi etc. There were also sound cards with SCSI controllers on them too. Luckily I had an IDE CDROM drive so I wasn't too worried about that.

 

On to the hard drive. I stuck in an old Quantum Fireball 1.2GB drive I had. A little anachronistic but it would allow plenty of space for the games :) I had a 486 back in the day that came with a 200mb drive, which we upgraded to a 1GB drive a few years later so its not impossible.

However, this machine wouldn't recognise any more than 504MB of space- basically a limitation of the CHS addressing scheme that the BIOS and drive use to store and retrieve data on the disk. So I tracked down a copy of Quantum Disk Manager which included Dynamic Drive Overlay software- basically, a software solution that translates the addressing scheme so you can access the full capacity of the drive. Its installed to the MBR of the hard disk, and loads before the operating system starts:

Posted Image

 

Now the fun part is putting everything together... unfortunately I've hit the image limit and these forums won't let me post twice in a row??? so this is 'to be continued' when someone else posts here ;)

Edited by DonutKing

Share this post


Link to post
Share on other sites

awesome sauce.

 

I had lost of fun with my 386s and 486s back in the day, but I'm not sure I'd ever want to try and get one of them up and running again.

Share this post


Link to post
Share on other sites

Weee!! :D

 

I built my 486DX2 system about a year ago:

 

Posted Image

 

The Roland Synth can't be beat for Sierra/LucasArts adventures.

 

I've done a write-up on selecting components for 486 systems, I'm almost ready to post it here, or to Cael for the Atomic Wiki.

Share this post


Link to post
Share on other sites

Ahh you have an MT32! I was chasing one of those but they seem quite expensive. Was also looking for a Gravis Ultrasound but they are even more espensive o_o

 

looks like FM Synth will have to do for now...

 

 

I've done a write-up on selecting components for 486 systems, I'm almost ready to post it here, or to Cael for the Atomic Wiki.

Please do I love reading about this old school type stuff :)

It seems to me that a LOT of 486 boards on Ebay are PC-CHIPS with fake cache so it would probably be handy to make mention of that somewhere if you haven't already...

 

Anyway, back to the build- now that everything is sorted out its time to put the thing together:

Posted Image

 

Everything connected and good to go :) Next step is to install an operating system- so I dug out my old MSDOS 6.22 disks and off we went:

 

Posted Image

 

Install went without a hitch. Now the fun part, installing all the drivers and software. First thing I did to make things easier, was to install the XTreeGold file manager program:

Posted Image

 

This was far superior to DOS Shell or Win3.1's file manager back in the day.

 

I talked about config.sys/autoexec.bat setup in the linked thread so I won't repeat it here, but basically I just loaded everything high, used the EMM386 switches mentioned in that thread and set it to AUTO mode, and used VIDE_CDD.sys for my CDROM driver. I was going to use UIDEJR.SYS but I had an issue in Return to Zork where it would just lock up when trying to play CD music, the VIDE_CDD.sys driver didn't have that issue and was still under 7kb when loaded. The official Sony CDROM driver for my drive was nearly 30kb so this new driver is a vast improvement. I didn't end up using DOSMAX, QEMM, or any other fancy memory managers, mainly for compatibilitybecause I still had 617kb conventional memory free.

 

DOS 5 and later come with a utility called MEMMAKER that is designed to maximise conventional memory, however I personally find that I can achieve better results by doing hte configuration by hand.

 

By setting EMM386 to AUTO and having 16mb of memory to play with, I can basically run any DOS game I come across without using a boot configuration menu. So you can play any game without rebooting, or knowing which config you need to choose- a great step for usability in my view. The ONLY game I've had trouble with is Ultima 7 which has a funny memory manager that clashes with EMM386 so I just use a boot disk for that.

 

Anyway, everything was chugging along so I decided its time to actually play on this thing and dug out my original copy of Sam and Max

 

Posted Image

 

This thing cost me $110 back in 93/94... still remember saving up for it for ages :P

 

 

Anyway, next step was to install QuikMenu 3 - I had this menu program installed on my 486 back in the day and it was an excellent little utility, and it seemed to unload itself when launching a game so you never had problems with memory usage. It was also much simpler to install, configure and use than Win 3.1.

 

Here's a screenshot of Quikmenu:

Posted Image

 

Here are a couple more screenshots showing various games installed. The games with mutliple episodes like Keen, Quest for Glory, I just wrote a simple batch file which uses the CHOICE command to prompt which game to play, and executes the correct file accordingly.

 

After a couple of weeks of digging up my old copies of games and installing them the machine is running perfectly, with a HEAP of old games on it and still ~200mb of free space.

 

Some games, like Scorched Earth, Strike 2, Wing Commander etc actually run too fast even on a 486DX2, luckily I found this program on Vogons that enables and disables the 486 internal cache which will slow it down enough to make these games playable. Just write a batch file to disable cache, start the game, then enable cache when its finished. :)

 

I've still got a few parts left over so I might try to build another one and whack a network card in each, so I can play multiplayer Doom/Warcraft2/Command and Conquer etc :)

I haven't bothered to install Windows 3.11 despite having disks for it... purely because none of the games I have require it. If I do get a network card and I get bored one day, I might try to track down an old copy of Winsock Trumpet and Netscape Navigator and try to get on the internet with it, just for shits and giggles - there's probably few sites left that will work properly with it, if the poor machine doesn't grind to a halt trying to render them :P I may also try Arachne which is a DOS based browser if I get the chance.

 

I've also got a couple of 386 boards and even a 286 board so when I find the time I will try and revive those too :)

 

In the meantime though, I'm loving revisiting the games of yesteryear :D

 

Posted Image

Edited by DonutKing

Share this post


Link to post
Share on other sites

This is fantastic!

 

What a trip down memory lane.

 

The pic of the AT power supply gave me shivers. I hated that bloody connector on the front. Most of the battle scars on my hands are from trying to get at those when swapping out a dead PSU and the god awful cases playing slice and dice.

Share this post


Link to post
Share on other sites

Ahh you have an MT32! I was chasing one of those but they seem quite expensive. Was also looking for a Gravis Ultrasound but they are even more espensive o_o

Yeah, I picked mine up off eBay in, uhh, probably 2006? They have been becoming increasingly expensive since then, I think I paid about $120 shipped from the USA.

 

The GUS is a mixed blessing. For the games it does support, the sound is magical, but for games that don't they're a bit of a nightmare. You need to load a TSR for them to emulate a SoundBlaster, and even then there are still compatibility issues, and it's a bit of a memory hog. A SB AWE32 is a better option if you want a wavetable synth.

 

The ONLY game I've had trouble with is Ultima 7 which has a funny memory manager that clashes with EMM386 so I just use a boot disk for that.

To avoid boot disks, you can use DOS's built in config menus:

 

CONFIG.SYS

[menu]
menuitem=noemm, No EMM386
menuitem=emm, Load EMM386

[common]
DEVICE=C:\DOS\HIMEM.SYS
DEVICEHIGH=C:\DOS\CD_DRIVER.SYS /D:MSCD001

[emm]
DEVICE=C:\DOS\EMM386.EXE

[noemm]
AUTOEXEC.BAT

 

@echo off
lh c:\dos\mouse
GOTO %CONFIG%

:emm
rem Do some stuff here
GOTO FINISH

:noemm
rem Do some other stuff here
GOTO FINISH

:finish
call c:\qm3\qm

I used to have a few options, with/without EMM386, with/without CDROM, with/without Networking, and so on.

Share this post


Link to post
Share on other sites

The pic of the AT power supply gave me shivers. I hated that bloody connector on the front. Most of the battle scars on my hands are from trying to get at those when swapping out a dead PSU and the god awful cases playing slice and dice.

Yeah I really can't say that I miss them... ATX was a great improvement.

 

Oh, the good old days of telling the mobo the cylinders and heads count.

Thankfully this BIOS has an IDE autodetect feature so that was pretty easy. But yeah I had an older board years ago that didn't and that was a real pain. Swapping drives is trivial these days.

 

 

To avoid boot disks, you can use DOS's built in config menus:

Yes but I explicitly wanted to avoid that, trying to make it as simple to use as possible:

By setting EMM386 to AUTO and having 16mb of memory to play with, I can basically run any DOS game I come across without using a boot configuration menu. So you can play any game without rebooting, or knowing which config you need to choose- a great step for usability in my view. The ONLY game I've had trouble with is Ultima 7 which has a funny memory manager that clashes with EMM386 so I just use a boot disk for that.

Edited by DonutKing

Share this post


Link to post
Share on other sites

oh lordy

 

We had DR-DOS 6 originally, had lots of stuff built in, but there was no GWBASIC or QBasic, which was annoying.

Share this post


Link to post
Share on other sites

Yes but I explicitly wanted to avoid that, trying to make it as simple to use as possible:

Right, but there is a default timeout option, you could just have a "Play U7" item, with the "Normal" item there with a 5 second timeout.

 

menuitem regular,Normal Startup
menuitem u7,Play Ultima 7
menudefault regular,5

Just to avoid the need for a floppy, and since you'd be rebooting anyway, and for normal use there is no interruption.

 

Edit: Oh, don't think I'm critisizing your work or choices, I'm just nerding out thinking of alternate ways to do stuff. The floppy method keeps it simple.

Edited by SquallStrife

Share this post


Link to post
Share on other sites

It's cool, I've heard that there are fanmade patches available for U7 that remove the funky memory manager, so I'm actually more inclined to track one of those down and give them a shot... ideally I wouldn't need to reboot to play it at all :)

Even back in the day it was a pig of a game to run.

Share this post


Link to post
Share on other sites

Why can't I "like" this thread?

 

I think the 486-DX33 was in part, directly responsible for my geekiness now. I remember reading PC Review back in 1994, and reading an article on its architecture - everything you said really: SX has no maths coprocessor but is still powerful enough to handle "the demands of Windows", a DX2 and DX4 were clock multiplied and suchlike.

 

Goddamn. I remember having a SB16 and just wanting a 32bit sound card so badly, and the one that everyone wanted then was a Gravis Ultrasound.

 

And monitors...I remember my old, boxy 14" beast that typically only played games in 320x240...and 640x480 was Super VGA and just out of this world =D

Share this post


Link to post
Share on other sites

I had a 14" SVGA monitor that had built in stereo speakers and a flat glass panel on the front.

Share this post


Link to post
Share on other sites

Why can't I "like" this thread?

I guess I can't please everybody :( :P

 

I'm currently using a 15" Philips CRT monitor, its about 5 years newer than the parts in the PC. I wouldn't mind tracking down an older monitor for that authentic experience...

 

It does support SVGA although the games I've tried that with - System Shock and Tie Fighter mainly- are really slow on this PC.

I think for these games a Pentium/PCI type system is the minimum for SVGA mode.

 

Also I needed to install the Scitech Display Doctor (aka UNIVBE) to get SVGA mode to work.

Edited by DonutKing

Share this post


Link to post
Share on other sites

Why can't I "like" this thread?

I guess I can't please everybody :( :P

 

He means "like" as in how Facebook has a "Like this" button, but this forum doesn't.

 

He does like it. ;)

Share this post


Link to post
Share on other sites

Why can't I "like" this thread?

I guess I can't please everybody :( :P

 

He means "like" as in how Facebook has a "Like this" button, but this forum doesn't.

 

He does like it. ;)

 

Posted Image

Share this post


Link to post
Share on other sites

Awesome.

 

My first PC was a Packard Bell 8088 with a CGA monitor. Dual 5.25 inch disks. I had to boot DOS 4.2 off 1 floppy.

 

After a few years I upgraded to a 486DX2 66mhz. That got blown up in a lightning storm, and Best Buy replaced it with a first generation Pentium 60. I thought I was so awesome. It worked so much better than the 486!

 

 

I wish I had the room in my house. I'd love to have an old DX2. Great post. Thanks for the memories.

Share this post


Link to post
Share on other sites

Heh, memories indeed. Actually, I've got one of those SB16 sound cards.

 

Still an awesome sound card. About its only downside is that it won't do sample rates above 44.1kHz, but otherwise, performs well.

 

Mine also has the Panasonic CD-ROM interfaces... we've also got a SoundGalaxy SGNX-PRO (8-bit, made by Aztech Labs) which has Panasonic, Mitsumi and Sony CD-ROM connectors IIRC.

Share this post


Link to post
Share on other sites

My first CD-ROM was a Sony model with a proprietary 40-pin connector (that looked exactly like a 40-pin IDE connector)

 

Couldn't get the thing to work under DOS/Windows, but initial playing around with Slackware Linux proved that it did in fact work.

Share this post


Link to post
Share on other sites

Mine also has the Panasonic CD-ROM interfaces... we've also got a SoundGalaxy SGNX-PRO (8-bit, made by Aztech Labs) which has Panasonic, Mitsumi and Sony CD-ROM connectors IIRC.

Funnily enough I had that exact same Sound Galaxy card in my 486 back in 93/94, but the motherboard battery leaked onto it and killed it. (This is why I'm not a fan of those barrel type batteries...) We ended up getting a SB16 as a replacement :D

 

My first CD-ROM was a Sony model with a proprietary 40-pin connector (that looked exactly like a 40-pin IDE connector)

Couldn't get the thing to work under DOS/Windows, but initial playing around with Slackware Linux proved that it did in fact work.

I actually have a Sony CDU33A in my box of parts here, which has a proprietary interface. I'm planning on building another box, probably a 386 with an SBPRO that has a Sony header, and I'm going to try using this drive with.

This one appears to be 34 pins though- a floppy cable fits into it.

Edited by DonutKing

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×