ancientelectronics

Continuing with the “Anatomy of” series we will be looking at perhaps the quintessential computer and CPU of the early to mid 90’s and a DOS mainstay. The 486 CPU was introduced in 1989 and continued to be refined and made faster. It stuck around well into the Pentium era of the mid 90’s. The PC were looking at today is based around the 486 and designed to run virtually any DOS game and program from the late 80’s up until the mid 90’s. it’s a little to fast and overkill for mid and early 80’s games and although certainly playable,  just a tad to slow for later DOS games such as Duke 3D or Doom. I find this setup to really be the perfect type for most DOS gaming in both compatibility and time specific feel (if that makes sense). It’s a little harder to find the parts for and maybe slightly more expensive than building a Pentium based DOS PC but the effort is worth it. I’ll be attempting to explain the parts necessary to put together a 486 PC but as always the suggestions are my opinions and there are many, many choices available. For quick reference I also have a page explaining various PC ports and slot types here.

I chose a desktop style case, I feel it better conveys the era and I personally like the form factor but you can just as easily chose a tower type configuration. This case is slightly larger than most I have seen on the market and has 3 5.25″ drive bays where most I have seen have 2. make sure you get an AT style case as your motherboard is going to be an AT form factor with most likely an AT power connector. Most of these cases can be found for less than $20 and many times come with a AT power supply. A lot of these cases have little slots for keys, don’t worry about them, you don’t need the key. this was so owners or businesses could lock the case to protect the insides from unwanted modifications or pilfering I assume. they usually come with 3 buttons, your standard power and reset as well as a “turbo” button. contrary to what you may think the “turbo” button actually slows the CPU down. This is to help with compatibility with older games that require a slower CPU. It’s a mostly useless feature but I suppose its nice to have to somewhat increase compatibility.

One thing you’ll notice about the back is that there are no PS/2 ports for keyboards or mice. The PS/2 standard had not taken hold yet and a  majority of 486 based motherboards did not have or support the connection, you will even find these AT style keyboard connections on early Pentium based boards.

1) AT keyboard connection. Finding an AT keyboard shouldn’t be hard. I spot them a lot at Goodwill in the piles of boards they usually have in one corner. the bulk will be USB or PS/2 but look for older off white colored boards and check the end connectors for the larger AT plug. The good news is that the AT connector is compatible with the PS/2 standard by way of an adapter plug. these can be found online for a few dollars and let you use a PS/2 type keyboard with the AT plug.

2) serial ports, The mouse is slightly more tricky. Serial mice are almost always the older style “ball mice”. They aren’t to rare and almost never more than $5. Unfortunately the connection is not electronically compatible with PS/2 so even with an adapter your PS/2 mouse may still not work. You need to look for serial/PS/2 compatible mice. sometimes this feature is stated on the mouse, usually it is not. You’re most likely better off just using a serial mouse. The other port is a 25 pin serial.

3) Parallel port, generally this is where you would plug in a printer to interface or a external Zip drive.

4) External SCSI port

5) Video port

6) Midi port

7) Gravis Ultrasound ACE

8) Sound Blaster 16 and joystick port

now to get into the meat of the setup.

1) the PSU or power unit. almost all 486 motherboards are going to have an older style AT power connector so you’re going to need a AT power supply. You don’t need one that’s very powerful 200 watts should suffice. Unfortunately these power units are getting a little hard to come by but on the plus side there is ATX to AT converter cables available for a few dollars. You’re also probably going to have to wire the PSU to the power button on the case unless you bought a case with the PSU already hooked up. this isn’t difficult and it’s just plugging 2 connectors. Mine is 250 Watts which should be enough for a machine of this time.

2) these are the larger 5.25′ drive bays. your almost defiantly going to want a CD-ROM drive installed. A lot of games in the era did have a CD release with enhanced sound and graphics. I’m using a CD-RW drive simply because I didn’t have a regular drive available at the time. these drives work fine for playing CD’s in DOS. there is no need to have a DVD drive since this format did not exist at the time. A DVD drive will also work and should operate just like a CD-ROM drive when installed.

The second drive I have installed is a 1.2MB 5 1/4 inch floppy drive. Almost all games of this era came on 1.44MB 3 1/2 floppies or CD so this drive really isn’t completely necessary but it you have an extra there’s no harm adding it on. It adds compatibility for some older games and also greatly enhances that classic PC look. I’ve also learned recently that there may be a few games that actually had content CUT to fit on a 1.44MB 3 1/2 floppy version. Tongue of the Fat Man is one such game with more content on the 5 1/4 floppy version.

Lastly I have my 500MB IDE hard drive installed in a removable Hard Drive caddy. Usually these caddy’s have a small fan for extra cooling and can be easily pulled out if you need to swap hard drives or your drive fails. I have my boot drive installed here and my games installed on my secondary hard drive. This way if my main drive fails I can easily swap in a new one.

3) The 2 3 1/2″ bays I have installed a IDE 500MB hard drive and a 1.44 MB 3 1/2″ floppy drive. a larger hard drive will work fine but as stated in earlier “Anatomy of” articles DOS only sees about 500MB without using partitions or tricks. the 1.44MB floppy drive is a must since many games were released on this format.

Under the 1.44mb drive I have my 100MB SCSI Zip drive. The SCSI variant is defiantly a little rarer and harder to find then the IDE based drives but i have noticed its a little faster, uses a smaller floppy type power connector and does not take up a space on my IDE chain since IDE only supports 2 devices per cable and SCSI can support over seven. It did take me a little time to hunt one down.

Finally under the Zip drive I have my secondary 1.4GB SCSI hard drive for my games.

4) The motherboard or MB. You’re really going to want a socket 3 motherboard to support the later 486 CPU’s. There all going to come with several 16 bit ISA slots but I highly recommend you find one that also has 1 or 2 VLB slots. you can look up this slot type on Wikipedia for more detail but they are longer connector slots usually a light brown in color. they were prevalent in the late 486 era and are faster at transferring information then the older ISA slots, roughly equivalent in speed to the later PCI type slot. PCI was still having the bugs worked out of it at this point so I don’t recommend a 486 board with PCI slots. My board has 2 VLB slots which is about the standard number. also make sure to note the MB type and do some research. MB’s of this era usually required jumper switches to change settings for things like CPU types and speed. fortunately though most 486 era MB’s do have the IDE and floppy connectors built in. I’m using a UM 486V AIO motherboard. It’s okay and serves the purpose though there are others out there that support more RAM and have more slots. mine has 256k cache as well as 2 VLB slots and 4 16 bit ISA slots.

Take note of the cache slots when buying a motherboard of this era as well. cache is very fast memory that the CPU makes use of. it is much faster then your standard system RAM and at the time was much more expensive so there were issues at the time with motherboards coming with empty cache sockets or even worse fake cache. L1 cache is located on the CPU itself but in the 486 days the L2 cache was on the motherboard. your board will operate with no L2 cache but it will take a stability as well as performance hit. My board can handle up to 256k of L2 cache which is plenty for the time period. You really want between 128k and 256k L2 cache. Some boards offer 512k or on high end boards 1mb but after 256k you really start to notice diminishing results so its not really necessary.

5) RAM. Most if not all of these era motherboards are going to use old 30 pin ram simms. there a little hard to find but not terribly expensive online. the MB I am using has 32MB which is also the most allowed, high end 486 MB’s could allow up to 64MB using 16MB simms. 32MB and defiantly 64MB is complete overkill for the era of gaming we are making this PC for. The majority of games from the time will happily run smoothly on as little as 8MB RAM. also make sure you research the RAM your MB needs, all 30 pin RAM is not the same and some boards are very picky on only accepting high or low density ram or things like EDO. for instance. most old PC’s use parity 9 chip ram in 30 pin simms. If the ram simm has 8 chips its non-parity and for a MAC. some MB’s you can adjust a setting in BIOS to allow the use of 8 chip RAM but many do not so make sure your using the correct type of RAM.

 6) CPU. The CPU I suggest and perhaps the all time classic 486 is the Intel 486DX2 66mhz CPU. I know there are several 486 CPU’s that were faster but the 66mhtz is without a doubt one of the most widespread and reliable of the time.  The 66mhtz was very widely used by DOS games and also gets along well with the VLB ports. make sure to couple the CPU with a heatsink/fan combo to extend the life of your system.

(image taken from Wikipedia as public domain)

7) serial port bracket and parallel port bracket. A lot of these older boards only have the keyboard connector built in so your going to need a diagram of your board (commonly available on-line if you know your MB type) and a bracket with the serial ports/parallel port and cable. If your lucky these will come with the 486 MB. You’re going to need the 9-pin male serial port for your mouse.

8) battery. The CMOS battery saves your BIOS settings. without it your going to be constantly configuring your drives and HDD on startup. 486 boards use a variety of battery’s from battery chips to barrel nickle-cadnium battery’s to lithium batteries on the higher end MB’s. My MB was very weird in the fact that the only battery connection available was a 4 pin external battery. these look like little bricks with a wire coming off and a connector on the end. they can go average for about $14. they usually have a side with adhesive so you can stick it to the side or inside case. I simply allow mine to dangle out the back.

9) SCSI card. I’m using a BusLogic BT-445S VLB SCSI card to handle any SCSI devices I use on this machine. SCSI or Small Computer System Interface is the alternative to IDE. In general its considered a little faster and more reliable then IDE but can be a headache to set up at times and the devices can be harder to find and costlier then IDE equivalents that’s why I like to use it in addition to my IDE. On my setup I have my secondary hard drive running on the SCSI bus. It is a newer 7200 RPM IBM SCSI hard drive detected as 1.4GB capacity. I primarily use this drive for my games. Another benefit of SCSI is that its not as size limited due to BIOS issues as drives connected to the IDE bus. You can also connect tape drives and CD-Rom drives to the SCSI bus and there is also an external connection. I believe I can connect up to 7 devices on this particular card. I originally had an Adaptec VLB card but it had a faulty BIOS chip so I switched over to this SiiG card which has worked well but was a sort of “bare bones” controller. I finally settled on the BusLogic card since it was a fair price and feature rich. Try to get a card that has features such as asynchronous transfer, large drive capability, DMA and bus mastering as these features will speed up your HDD access. Take note though if your using as later 486 motherboard and have your ram set to “write-back” you’re almost assuredly going to have bus conflict issues when adding a vlb SCSI device. As far as I know there’s no way around it. Its either write back RAM or the VLB SCSI but using a ISA SCSI card should work fine though it will be slower. Adding a SCSI card is completely optional but I think it improves your device options and ups the “coolness” factor.

10) graphics card. There are many options available for graphics cards in this era. since 3D accelerations is really not a consideration for this era we need an excellent 2D card. since our board should have at least 1 VLB slot we should focus on a VLB card. as I said before PCI was still having the bugs worked out of it at this point so I don’t recommend a 486 board with PCI cards. Previously I was running a Diamond Speedster Pro VLB card with 1MB of onboard RAM. 1MB for the most part is all the video RAM you need. there are some reported issues with sound interference or crackling when using a Speedster Pro VLB with a Sound Blaster 16 but the number of games is limited and I have never personally come across this issue. If you must have the top of the line though and the current card I am using hunt down a Tseng Labs ET4000 VLB card. It’s widely regarded as the fastest VLB card. Mine came with 1MB of RAM but I added more to make a 2MB card. Buying the RAM individually can be a little pricey so look for an old cheap Trident card and harvest its RAM, just be careful which way you inset it. These cards can be a little pricy but they are very compatible and very fast.

11) Midi card. The midi card I currently have installed is a Roland mpu-401-T. I use this card to run all my external Midi devices such as the MT-32. Prior to this card I used my Sound Blaster 16 to control my midi devices but That setup was prone to games not working because they required a true midi interface card or they fell victim to the dreaded “hanging midi note” bug that effects midi modules connected via sound blaster midi ports. These are 8 bit ISA cards but work just fine in a 486 16 bit slot. keep in mind there are several versions of the card and mine is the 401-T version. You will also require a “midi breakout box” to interface with your external modules. make sure your box is the same as the ISA card your using or it will not work. They are wired differently and I found that out the hard way.

Connected to my breakout box and Midi interface card is my Roland MT-32 module. The MT-32 sound module really deserves an article of its own on its features and how to set one up so I’m just going to briefly go over it here. There is a revision of this module that’s almost identical except for a rear headphone jack and internal updates. There are a small number of games that work incorrectly with the old version but correctly on the new version and a small number that work incorrectly with the new revision but correctly on the old one so the ultimate setup would include both modules. there is also an internal version the LAPC-I that I believe is based on the old module. Basically this was the Cadillac of sound devises and was capable of sound quality far ahead of the cards available at the time. A lot of games support the MT-32 standard and most sound brilliant for music. I urge you to go on YouTube and look up “MT-32” comparison videos and hear for yourself the difference. For maximum compatibility I have my MT-32 paired with the SB16. To avoid conflict my SB16’s midi port is set to port 300 and my midi card is set to port 330 which is the default port that most games look for. The MT-32 handles music when the option is available and the SB16 the digital sound effects. Many games will allow for the SB16 to be used for sound effects while the MT-32 handles the in-game music.

Another indispensable midi module would be a Roland Sound Canvas SC-55 or SC-55 MKII. These modules support general midi and Roland midi which many later DOS games support. These games may support general midi but NOT MT-32. Th SC-55 can also emulate the MT-32 but may not sound perfect compared to a actual MT-32. The earlier SC-55 is said to be slightly more compatible with older DOS games while the SC-55 MKII may perform better with a few late DOS titles.

12) Gravis Ultrasound ACE. The Gravis Ultrasound was a competitor to the sound Blaster. Although it wasn’t as widely supported as the SB it was still supported in a variety of games and offered much higher quality sound and at times even improved game performance. The card I’m using is the ACE which is a stripped down version of the regular card. I’m using this card because Sound Blaster emulation on a Gravis was not very good and the ACE was designed to work in a machine alongside a Sound Blaster. Unlike regular cards you can disable the adlib emulation on an ACE and with the Ultrasound initialization program v. 2.26a available here, you can also disable the game port option so you have no conflicts with the Sound Blaster.

13) Sound card. I’m using a later model Sound Blaster 16 Vibra ISA card for FM sound and digital effects. The Sound Blaster 16 or SB16 is really a no brainier for this era in PC gaming. It is backwards compatible with the Adlib standard and almost every game of the period supported Sound Blaster sound. They are fairly cheap and easy to find giving the best compatibility and performance for the early to mid 90’s era. There are more capable cards like the AWE series or the Gravis Ultrasound but I feel you sacrifice compatibility and these cards are better suited for faster Pentium based PC’s.

Also a strong argument can be made to use a earlier 8-bit Sound Blaster Pro or sound blaster. The Sound Blaster 16 is NOT fully compatible with the sound blaster and older software often sound better on it. with the exception of perhaps the Vibra model SB16 cards the Sound Blaster pro has a lower sound to nose ratio. keep in mind that the sound blasters before the SB16 do not have midi ports compatible with the MPU-401 standard meaning you cannot use them to hook up external midi modules. I have recently debated replacing my sound blaster 16 with a older sound blaster but since I have some older PC’s that I can use for that purpose I’ll stick with the good all around Sound Blaster16 card.

The SB16 model I am using is the CT2900. it uses the VIBRA chip but also has the Yamaha OPL FM chip. try to use a SB with the OPL FM chip as many later models lack this chip.  and without it some sounds that use FM end up sounding off. If your observant you’ll notice in the full picture of the open 486 above the sound card is different, shortly after taking that picture I found the better model CT2900. the model I was using prior lacked the Yamaha OPL chip.

14) MPEG decoder card. (not pictured above) This is the newest edition to my 486 and thus not in the motherboard images above. It is a 16 bit ISA RealMagic MPEG decoder card. This card allows a 386 or 486 CPU machine to decode MPEG video which otherwise would be to taxing to the CPU. I plan to use this card for playing RealMagic enhanced games. admittedly the games that support these cards are few and rare and have to be a special version supporting the card. I believe there are RealMagic enhanced versions of Dragons Lair, Space Ace, Return to ZORK and The Horde as well as possibly a few others. Using the card allows for smoother  and better looking full motion video scenes as well as possibly other effects.

There are cards that connect via a external passthrough such as this card and others that connect directly to your video card via a VESA connector cable internally. The VESA connector cards tend to produce a better image quality but are less compatible then the passthrough cable cards.

For a joystick I’m using the Microsoft Sidewinder 3d pro. this joystick is a duel digital/analog joystick that works in DOS as well as Windows 95 and has a little switch underneath the base to choose modes. I previously was using a Seitek joystick which although was very compatible was very stiff and not so much fun to use. So far the sidewinder has been a great joystick and tends to do the job quite well in whatever flight/flight shooter I throw at it in DOS. Not the best when compared to some Thrustmaster flight controllers but I think it makes an excellent all around stick.

For games where I would rather use a more conventional gamepad rather then a joystick I go with the Gravis Gamepad. Its comfortable and compatible. The joystick bar can be unscrewed if desired and they can be found cheap at thrift stores, commonly under $5.

I run DOS 6.22 on my 486 PC and use no navigators or Windows 3.1. A navigator shouldn’t cause any issues but I’m aware of a small number of games that Windows 3.1 may cause compatibility issues with. All in all the 486 based DOS PC is going to be a little more expensive and require a little more effort to put together than a Pentium based one, perhaps $50 to $100 unless you can find one cheap on Craigslist or a yard sale. In my opinion its worth it as it gives you access to a vast collection of excellent early 90’s games without having to worry about CPU speed issues as well as the satisfaction of gaming on an all time classic PC setup.

Things I still need to add to this setup

*add more external sound modules (Roland cm-32,)

Here’s some older images of this machine playing some games.

article updated 10/30/2015