6 ms·

The (Almost) Definitive 486DX/50 Article

114 points by ibobev 4y ago

alberth 4y ago
This bring back fond memories. I had a 486DX2/66
- UI_at_80x24 4y ago
  I worked in a computer store while attending college during this time. We were the only "Computer store" in town, but the local BigBox "furniture store" also sold computers too. None of the staff there knew anything about computers. We would often have people come into our shop asking questions and then going to the BigChain to buy the PC's. Well, one day a couple came into the store carrying the flyer for the other place. The couple then asked several questions about the computers, "What does this mean, What does that do, Is this part important... etc" I tried several times during the discussion to steer them towards the products that we sold. It was obvious that they were only using my time to educate themselves so they could 'smartly shop' at the other location. So we get to the part of the listing where the choice was DX vs DX2 (33Mhz vs 66MHz IIRC). Them: "What does the 2 mean?" Me: "That's needed if you want to use two floppy drives, both a 5.25" and a 3.5" or just one." fun times..... =) *Edit/Note: the 2 in DX2 means that it was clock-doubled. I lied to the customer because they were wasting my time.
  - alberth 4y ago
    That's a great story. Had no idea about that either. In my case, I had a Packard Bell - which had 1 floppy & 1 CD-ROM. https://www.weavweb.net/2020/09/22/packard-bell-486-dx2-66mhz/ https://www.weavweb.net/2020/09/22/packard-bell-486-dx2-66mh...
    - navjack27 4y ago
      You had no idea about it because it's false
      - UI_at_80x24 4y ago
        Correct. I lied to somebody that was wasting my time.
    - 1970-01-01 4y ago
      Those PackardBell CD-ROM games and encyclopedias were very innovative. I have several of those PCs and still have all their CDs. Check out 3D Body Adventure predicting the pandemic: https://youtu.be/VlxyjOLBKbg?t=980 https://youtu.be/VlxyjOLBKbg?t=980
      - alberth 4y ago
        Yes!!! I totally remember that and loved it. Thanks for finding the video link. Brings back great memories.
- isolli 4y ago
  Lucky you! I could only afford a 486 DX/33, but at least I splurged for 230 MB of hard drive.
- antx 4y ago
  Heck yeah, I went from a C64 to a 386SX (which youngin me eventually broke by trying to upgrade memory), to a 486DX2/66 which allowed me to FINALLY play doom. Then followed a Cyrix 5x86 100GP in somewhere around 1996, which was a bit of an upgrade, since I could not afford Pentiums just yet with my own money. In 1997, I bought a Diamond Stealth II S220 as an alternative to a Voodoo, for the same "poverty" reasons. You have to know my parents were ... very much against computers. As we started to get access to the internet in high school, I learned about overclocking, and oh my! was my system the best candidate for it! I could push the CPU to 120Mhz without additional cooling! The graphics cards, which bore a rendition verite v2100 chip, could also be overclocked quite heavily, but since the chips where bare, without any form of cooling, it became too hot, so I had to "MacGyver" my way around the problem. I also have very fond memories of the socket 3 era... for me it started with the classics from id software, to Warcraft 2, Duke3D, LAN matches, Carmageddon, Quake, etc.. and all the early mods such as paintball, skin modding, what fun!
  - bluedino 4y ago
    > I bought a Diamond Stealth II S220 as an alternative to a Voodoo I did the same thing, it was a great budget card. vquake was awesome, plus you were able to use Direct3D inside of Windows which the first 3Dfx cards didn't do. It also came with a Descent clone called Forsaken on the demo CD, which was the first colored lighting I had ever seen in a game, and was pretty amazing. Ironically, the Verite chips didn't handle certain VGA modes that well, so DOS games like Doom were pretty choppy.
    - antx 4y ago
      Oh yeah, tomb raider was fun, but vquake was the bomb. Although, eventually, when the miniGL port was released, it was clear that the V2x00s were sub-par, even with 24 bit support and hardware z-buffer. Eventually the voodoo2 just put the nail in the coffin. But for a time, little geek me had fun pushing the hardware limits, even though I knew nothing of thermal management at the time. Indeed, I remember some DOS games having some... stutters? For lack of a better term. But at that point I was hooked on 3D and Windows 9x, so it didn't matter too too much.
    - 4y ago
- mschaef 4y ago
  I went 8088->386SX->486DX/33->P5/100->... The 386SX transition was nice, because it also brought Windows (with its standard printer drivers) and enough memory and video capability to start to do interesting work with graphics. It brought most of what I'd call the baseline capabilities of a modern computer, with the subsequent generations mainly just adding capacity. It was interesting at the time, though, that the 486 I had was mainly heavily constrained by expansion bandwidth. It had an accelerator for the video, but the connection from the CPU into the video card was just 16-bit ISA. Anything that had to transit the bus was glacial - so it couldn't really do more than 8bpp graphics. It was a great argument in support of local bus (and a source of some amount of envy when VLB DX2/66's started showing up... computationally only about double speed, but so much more capability to drive the screen).
  - prmoustache 4y ago
    Our Family went straight from the 8088 + cga graphics to the pentium 100mhz (really an overclockerd 90mhz model) + sound blaster card + matrox something and a decent Sony screen . Quite a big jump :)
    - deckard1 4y ago
      same here. We had an 8088 with AdLib, which only had FM synthesis. We stepped up to a Pentium 75Mhz with SoundBlaster AWE32 and 16-bit 44.1kHz audio. And CD-ROM drive! Those were amazing times. Shortly after that the internet hit mainstream and MP3s became a thing, and the world changed forever.
      - JohnBooty 4y ago
        The AWE32 was amazing. I remember being so frustrated that essentially no games seemed to take advantage of it. That's actually the time period when I started to fall in love with game music. I'd download MIDI files of songs from 16-bit games. On most setups, they sounded quite bad. But in MIDI software that supported the AWE32's soundfonts a lot of them sounded incredible.
velmu 4y ago
An amazing article.
- antx 4y ago
  Amazing indeed! I'd also wish for a pentium pro article on the same vibe. Many people don't realize that it paved the way to even the current "core" series! In some ways, like the DX50, it was even better than its successors, although it was plagued by issues.
  - myself248 4y ago
    You may appreciate the Red Hill hardware pages: https://www.redhill.net.au/iu.php https://www.redhill.net.au/iu.php
    - antx 4y ago
      ahhhh, yes, thank you!
Veliladon 4y ago
The biggest problem with the DX/50 was the bus. AMD was already struggling to run the VLB at 40MHz with their DX-40 parts. A lot of video cards couldn't handle it and running certain hard drives controllers on that speed sometimes ran the risk of corrupting disks. I can imagine that the DX/50 was a hellscape of I/O trying to find cards that could run at the 50MHz bus clock or being stuck at EISA's 33MB/sec.
- danbruc 4y ago
  My first PC was a 486DX/50 and until today I was totally unaware of the potential bus timing issues but I can not remember ever having had issues. But this might finally explain why it came with a turbo button - even though it should probably be called an anti-turbo button - that allowed changing the clock to 10 MHz. But now I wonder why they would have made it that slow instead of say 25 MHz or 33 MHz? I vaguely remember using the slower clock to make games playable that were running way to fast, so maybe that also factored into it.
  - elzbardico 4y ago
    If I am recalling correctly the turbo button was a workaround for software that had problems running at the high speeds. But I may be mistaken.
    - Koshkin 4y ago
      You remember correctly. (Remarkably, GORILLA.BAS did not have that problem.)
  - AdrianB1 4y ago
    The Turbo button did exist on processors that ran over 4.77 MHz of the original 8086. I had a Turbo button on the 9.54 MHz 8088, also on the 386 DX/40 (lowering the frequency to 8 MHz IIRC), it was not specific to 486. Actually the 486 was the last CPU that had that button, I think.
- myself248 4y ago
  I had one of those AMD 486DX40's and it was a screamer. Yes, very picky about VLB card choice and even placement; we had a big multi-IO card (possibly made by DFI?) and a Trident SVGA card, and it took a few days of shuffling and benchmarking and stability testing to find the optimum arrangement. ISTR that if the IO card was closest to the CPU, it simply wouldn't boot about half the time, and it was unstable if it did. Putting the IO in the third VLB slot and the video card in the second, leaving the first empty, seemed to be the best arrangement. And it left the IDE cables reasonably close to the drives, so that was a win. But once we got all the drivers loaded for that IO card and stuff, it absolutely flew. Ran rings around a lot of Pentium/90 systems because their 33MHz bus just couldn't keep up, and in the days before GPUs, pushing pixels into video RAM was a contest of raw bus bandwidth and very little else. We eventually had quite a lot of drives on that machine, so UDMA/33 moved a lot of bytes while still leaving spare bus cycles for overhead. I tried overclocking it to 50MHz a few times, and the IO and VGA cards were both capable, it was the RAM that shat itself. The upper 3MB of RAM would just vanish, leaving only 1MB, which was honestly a fair tradeoff for some things -- I'd boot in that config if I had a lot of PKZIP to do, or for rendering fractal graphics, which didn't use a lot of RAM but really appreciated the extra clock speed. Then clock it back down and reboot to use the results of those operations. Underclocking was also nice, and something I did frequently, so I could unplug the CPU fan and enjoy some quietude during a long BBS file transfer, which certainly didn't need much CPU grunt. The mobo clock generator didn't mind being re-jumpered while the system was on, and going from 40MHz to 16MHz (I think) was a simple matter of adding or removing one jumper cap, as I recall. I could reach through the floppy-drive opening in the front of the case and do this after a download started. Then switch off the monitor, and listen to the quiet tick-hiss of interference on my FM radio, which picked up just enough of WHYT 96.3 in the basement that I could listen to some alt-rock while also being aware of the UART ISR being hit. When the ticking stopped, the modem was idle, turn the monitor back on, jumper the CPU back up to speed and plug the CPU fan back in while the CRT warmed up, and get on with unpacking the file.
qbasic_forever 4y ago
Had an AST 486DX2/50 as my first PC in ~93 or so--I have a lot of good memories poking around DOS, playing Doom, tons of shareware, dialing BBSes (on a 2400 baud modem!) and more. It was a great machine.
mobilio 4y ago
I had DX/33 DX/50 and then DX2/66 plus DX4/120 I remember that before DX2/66 i wasn't seen on chip labels about "heatsinks". On DX2/66 there was label "heatsink required". But on DX4 label was "heatsink and fan required".
- tecleandor 4y ago
  And also "Peel this label before putting the heatsink". I know people left the sticker there... with consequences.
- jeffbee 4y ago
  Yeah people have forgotten this but when the Pentium came out and all Pentium PCs required a CPU fan, this was criticized by many reviewers. Now I have an Intel CPU with a motorcycle-sized radiator and a coolant pump :-|
  - qbasic_forever 4y ago
    Such a silly criticism too since hard drives of the era were so obnoxiously loud.
  - mmcgaha 4y ago
    I had a pentium 66 with just a huge heat sink. My pentium 133 had a fan but when I upgraded to a k6-2 I under clocked it so I could just use a heatsink. It was 2015 before I finally got another fanless computer.
- hulitu 4y ago
  I had an AST Cyrix 486 DX/2 66 without heatsink.
fsagx 4y ago
My first PC was a 486DX50 from the bargain bin (with no box or accessories) at Best Buy. I never had a fully new system again, as each newer configuration still had many parts of the old ones. Very Ship of Theseus.
NotYourLawyer 4y ago
This takes me back, although my first computer was a 486SX 25 MHz. At some point I inadvertently over locked it (long before I heard that word) because there was a jumper to change the bus from 25 to 33. I couldn’t believe it just… worked!
bluedino 4y ago
The 486 was such a massive improvement over the 386. And the DX2/66 felt like almost as big of an improvement over the 25/33MHz 486's. The 486 landscape was weird. You had crippled, 386-like versions such as the 486DLC/SLC, Intel's DX4's that hit 75 or 100MHz, and clones that went up to somewhere around 133MHz (by this time the Pentiums had hit the streets, so the 486's on steroids were for budget users). And they were often given similar sounding names to the 586, to further confuse buyers. It was amazing, and infuriating, to have your decently high-end system basically obsoleted in two generations. And, the DOS to Windows transition didn't help matters. It seems really odd in a time where you could still be using a 10 year old i7 and be just fine.
- ido 4y ago
  486DLC/SLC were not really "crippled versions", they were completely different CPU designs that used the 486 name as Intel wasn't able to stop other companies from using a number (one of the reasons for naming the next cpu family "pentium" which they could trademark/copyright). The crippled versions were the 486SXs, which disabled the FPU.
  - dspillett 4y ago
    > The crippled versions were the 486SXs, which disabled the FPU. Though for many use cases at the time, that wasn't a massive issue. Many games didn't take advantage of the FPU until far into the 486 era, they were only starting to when the Pentium and its competitors came out (a killer for Cyrix's P5-era chips which despite a very strong integer performance had terrible floating-point umph). There were 487 FPU co-processors, to upgrade 486SXs, though unlike the 287 and 387 before them they weren't really co-processors, they were actually full 486 chips and the main CPU was disabled when they were present. The name caused confusion because SX in 386 meant something completely different (there was no built-in FPU to disable): a 16-bit data bus instead of 32-bit and 24-bit address bus, along with more minor changes, so it would work on cheaper motherboards originally designed with 286's in mind.
    - bluedino 4y ago
xenon2 4y ago
Very interesting article. On side note, I've had Am486Dx4VT8 (8 kb internal cache in WT mode). I was able to run it in 2x50MHz mode with Trident VLB card - it was my first "overclock" to have somewhat playable Quake experience (but not really).
newfie_bullet 4y ago
My first computer was an IBM EduQuest 486 SX/50 (https://www.ardent-tool.com/EduQuest/EduQuest_55.jpg https://www.ardent-tool.com/EduQuest/EduQuest_55.jpg) - great memories of taking that apart and learning about how things worked (glad my parents didn't know what was going on after spending $2000 on a computer for 'school work')
johnklos 4y ago
It was a very interesting time in computing history. The changes from the i80286 to the i80386 were extreme - the i386 gave us a fundamentally different instruction set that common 32 bit systems still use in 2023. On the other hand, the changes in the i80486 were purely about speed: relatively large built-in caches, integrated FPU, significantly better pipelining and so on. It was the last time Motorola really competed with Intel. The m68040 was all about performance, too, and Motorola's chip was faster in integer, floating point, synthetic and real world uses, clock for clock. (The m68060 was somewhat competitive with the Pentium, but people weren't choosing between x86 and m68k by then.) The x86 world really owes some thanks to Motorola for the competition. However, the fact that Intel was selling '486s like hotcakes meant they spent the time and money to continue to improve the '486, so the clocks went way up. The m68040 never had any clock improvements over 40 MHz. An i80486 system can still run NetBSD decently in 2023, which is a testament to the generally good performance of the CPU :)
- chungy 4y ago
  Intel pushed the 486 up to 100 MHz via the iDX4 chip (which lost the i486 branding, but it's still what it is). Initially intended for embedded systems, it was sold directly also to consumers with the "OverDrive" brand attached. (Maybe it was unsold stock from the embedded attempt?) AMD would further push its own 486 chips to 150 MHz, and I recall the raw clockspeed allowed it to stay competitive against the lower-end Pentiums (60-75 MHz), but architectural changes in the Pentium (branch prediction and out of order execution) really let the Pentium fly away from the 486 at fewer necessary cycles.
  - mschaef 4y ago
    > Initially intended for embedded systems, it was sold directly also to consumers with the "OverDrive" brand attached. They also spent some effort marketing the DX4 as a low end alternative to the Pentium. It was possible to buy/build DX4 machines. Trouble there is the same as any other low end offering of the time - it got steamrolled by better technology coming down in price as quickly as it did. The window of opportunity for anything low end was not that large.
  - 4y ago
balls187 4y ago
Our first PC was an AST Advantage 486dx/33 Purchased from the McChord AFB computer shop. Originally my dad wanted to “upgrade” our Amiga1000 to be PC compatible, but learned such a thing was not possible.
- timbit42 4y ago
  You could have upgraded to an Amiga 2000 and put a Bridgeboard in it or a third-party one with a 486 on it. You could even upgrade it to a Pentium Overdrive processor. The Amiga was also able to run Mac OS as a task on it's own "screen" alongside Workbench and other Amiga apps, so you could run Amiga, Mac and IBM PC software all at the same time at full speed.
tedunangst 4y ago
> It's possible that some operations, particularly those that involve memory- or disk-intensive access, may actually be slower with the DX2/66 than with the DX/33. Some things never change. The mechanical translation of "not faster than" to "slower than" is ever prevalent.
fabiensanglard 4y ago
Gorgeous article. - Topic close to my heart. - Loads of references at the bottom. - Oh my god, it even features the publication date at the top.
marttt 4y ago
Are there any moderately priced 486 SBCs available these days? The ones I've encountered (forgotten the links) were in the $200-or-so range. Surprisingly expensive, or not? I would love to have a dirt cheap fanless 486 minicomputer for FreeDOS (SvarDOS). Not for gaming, mostly for writing and some hobbyist coding. (I'm an ultra-slow thinker, so a single-tasking system is very probably plenty for most things. :) Currently thinking about this one, with Vortex86 -- but it is still, well, fairly expensive as compared to something like a RasPi: https://icop-shop.com/product/ebox-3100/ https://icop-shop.com/product/ebox-3100/ As for fanless and low spec, there is, of course, this wonderful table of thin clients: https://www.parkytowers.me.uk/thin/hware/hardware.shtml https://www.parkytowers.me.uk/thin/hware/hardware.shtml
- tomatocracy 4y ago
  Alternatively, a Raspberry pi 4 should be powerful enough to run PCem emulating a 486 class system I think.
  - marttt 4y ago
    Sure, there are emulators, but I was thinking of a native system. Emulators seem to work great, but I try to avoid several layers of abstractions. Also, feeling nostalgic about how a native FreeDOS system boots in literally 2 seconds (on a modest laptop), I guess. Someone built this: https://www.youtube.com/watch?v=ZBsv-jRiIT8 https://www.youtube.com/watch?v=ZBsv-jRiIT8 And this, the weeCee; the price point estimated in the comments is around $600, though: https://www.youtube.com/watch?v=USHvvSbYmJA https://www.youtube.com/watch?v=USHvvSbYmJA A third one, with lots of diy involved: https://github.com/eivindbohler/tinyllama https://github.com/eivindbohler/tinyllama It is interesting nonetheless that really-low-spec SBCs have not gone into the masses (thus resulting in dirt-cheap prices) the way the RPis have. It is still a nice dream to see this happening with the current rise of retrocomputing.

114 points by ibobev 4y ago

alberth 4y ago

This bring back fond memories. I had a 486DX2/66

UI_at_80x24 4y ago
I worked in a computer store while attending college during this time. We were the only "Computer store" in town, but the local BigBox "furniture store" also sold computers too. None of the staff there knew anything about computers. We would often have people come into our shop asking questions and then going to the BigChain to buy the PC's. Well, one day a couple came into the store carrying the flyer for the other place. The couple then asked several questions about the computers, "What does this mean, What does that do, Is this part important... etc" I tried several times during the discussion to steer them towards the products that we sold. It was obvious that they were only using my time to educate themselves so they could 'smartly shop' at the other location. So we get to the part of the listing where the choice was DX vs DX2 (33Mhz vs 66MHz IIRC). Them: "What does the 2 mean?" Me: "That's needed if you want to use two floppy drives, both a 5.25" and a 3.5" or just one." fun times..... =) *Edit/Note: the 2 in DX2 means that it was clock-doubled. I lied to the customer because they were wasting my time.
- alberth 4y ago
  That's a great story. Had no idea about that either. In my case, I had a Packard Bell - which had 1 floppy & 1 CD-ROM. https://www.weavweb.net/2020/09/22/packard-bell-486-dx2-66mhz/ https://www.weavweb.net/2020/09/22/packard-bell-486-dx2-66mh...
  - navjack27 4y ago
    You had no idea about it because it's false
    - UI_at_80x24 4y ago
      Correct. I lied to somebody that was wasting my time.
  - 1970-01-01 4y ago
    Those PackardBell CD-ROM games and encyclopedias were very innovative. I have several of those PCs and still have all their CDs. Check out 3D Body Adventure predicting the pandemic: https://youtu.be/VlxyjOLBKbg?t=980 https://youtu.be/VlxyjOLBKbg?t=980
    - alberth 4y ago
      Yes!!! I totally remember that and loved it. Thanks for finding the video link. Brings back great memories.
isolli 4y ago
Lucky you! I could only afford a 486 DX/33, but at least I splurged for 230 MB of hard drive.
antx 4y ago
Heck yeah, I went from a C64 to a 386SX (which youngin me eventually broke by trying to upgrade memory), to a 486DX2/66 which allowed me to FINALLY play doom. Then followed a Cyrix 5x86 100GP in somewhere around 1996, which was a bit of an upgrade, since I could not afford Pentiums just yet with my own money. In 1997, I bought a Diamond Stealth II S220 as an alternative to a Voodoo, for the same "poverty" reasons. You have to know my parents were ... very much against computers. As we started to get access to the internet in high school, I learned about overclocking, and oh my! was my system the best candidate for it! I could push the CPU to 120Mhz without additional cooling! The graphics cards, which bore a rendition verite v2100 chip, could also be overclocked quite heavily, but since the chips where bare, without any form of cooling, it became too hot, so I had to "MacGyver" my way around the problem. I also have very fond memories of the socket 3 era... for me it started with the classics from id software, to Warcraft 2, Duke3D, LAN matches, Carmageddon, Quake, etc.. and all the early mods such as paintball, skin modding, what fun!
- bluedino 4y ago
  > I bought a Diamond Stealth II S220 as an alternative to a Voodoo I did the same thing, it was a great budget card. vquake was awesome, plus you were able to use Direct3D inside of Windows which the first 3Dfx cards didn't do. It also came with a Descent clone called Forsaken on the demo CD, which was the first colored lighting I had ever seen in a game, and was pretty amazing. Ironically, the Verite chips didn't handle certain VGA modes that well, so DOS games like Doom were pretty choppy.
  - antx 4y ago
    Oh yeah, tomb raider was fun, but vquake was the bomb. Although, eventually, when the miniGL port was released, it was clear that the V2x00s were sub-par, even with 24 bit support and hardware z-buffer. Eventually the voodoo2 just put the nail in the coffin. But for a time, little geek me had fun pushing the hardware limits, even though I knew nothing of thermal management at the time. Indeed, I remember some DOS games having some... stutters? For lack of a better term. But at that point I was hooked on 3D and Windows 9x, so it didn't matter too too much.
  - 4y ago
mschaef 4y ago
I went 8088->386SX->486DX/33->P5/100->... The 386SX transition was nice, because it also brought Windows (with its standard printer drivers) and enough memory and video capability to start to do interesting work with graphics. It brought most of what I'd call the baseline capabilities of a modern computer, with the subsequent generations mainly just adding capacity. It was interesting at the time, though, that the 486 I had was mainly heavily constrained by expansion bandwidth. It had an accelerator for the video, but the connection from the CPU into the video card was just 16-bit ISA. Anything that had to transit the bus was glacial - so it couldn't really do more than 8bpp graphics. It was a great argument in support of local bus (and a source of some amount of envy when VLB DX2/66's started showing up... computationally only about double speed, but so much more capability to drive the screen).
- prmoustache 4y ago
  Our Family went straight from the 8088 + cga graphics to the pentium 100mhz (really an overclockerd 90mhz model) + sound blaster card + matrox something and a decent Sony screen . Quite a big jump :)
  - deckard1 4y ago
    same here. We had an 8088 with AdLib, which only had FM synthesis. We stepped up to a Pentium 75Mhz with SoundBlaster AWE32 and 16-bit 44.1kHz audio. And CD-ROM drive! Those were amazing times. Shortly after that the internet hit mainstream and MP3s became a thing, and the world changed forever.
    - JohnBooty 4y ago
      The AWE32 was amazing. I remember being so frustrated that essentially no games seemed to take advantage of it. That's actually the time period when I started to fall in love with game music. I'd download MIDI files of songs from 16-bit games. On most setups, they sounded quite bad. But in MIDI software that supported the AWE32's soundfonts a lot of them sounded incredible.

velmu 4y ago

An amazing article.

antx 4y ago
Amazing indeed! I'd also wish for a pentium pro article on the same vibe. Many people don't realize that it paved the way to even the current "core" series! In some ways, like the DX50, it was even better than its successors, although it was plagued by issues.
- myself248 4y ago
  You may appreciate the Red Hill hardware pages: https://www.redhill.net.au/iu.php https://www.redhill.net.au/iu.php
  - antx 4y ago
    ahhhh, yes, thank you!

Veliladon 4y ago

The biggest problem with the DX/50 was the bus. AMD was already struggling to run the VLB at 40MHz with their DX-40 parts. A lot of video cards couldn't handle it and running certain hard drives controllers on that speed sometimes ran the risk of corrupting disks. I can imagine that the DX/50 was a hellscape of I/O trying to find cards that could run at the 50MHz bus clock or being stuck at EISA's 33MB/sec.

danbruc 4y ago
My first PC was a 486DX/50 and until today I was totally unaware of the potential bus timing issues but I can not remember ever having had issues. But this might finally explain why it came with a turbo button - even though it should probably be called an anti-turbo button - that allowed changing the clock to 10 MHz. But now I wonder why they would have made it that slow instead of say 25 MHz or 33 MHz? I vaguely remember using the slower clock to make games playable that were running way to fast, so maybe that also factored into it.
- elzbardico 4y ago
  If I am recalling correctly the turbo button was a workaround for software that had problems running at the high speeds. But I may be mistaken.
  - Koshkin 4y ago
    You remember correctly. (Remarkably, GORILLA.BAS did not have that problem.)
- AdrianB1 4y ago
  The Turbo button did exist on processors that ran over 4.77 MHz of the original 8086. I had a Turbo button on the 9.54 MHz 8088, also on the 386 DX/40 (lowering the frequency to 8 MHz IIRC), it was not specific to 486. Actually the 486 was the last CPU that had that button, I think.
myself248 4y ago
I had one of those AMD 486DX40's and it was a screamer. Yes, very picky about VLB card choice and even placement; we had a big multi-IO card (possibly made by DFI?) and a Trident SVGA card, and it took a few days of shuffling and benchmarking and stability testing to find the optimum arrangement. ISTR that if the IO card was closest to the CPU, it simply wouldn't boot about half the time, and it was unstable if it did. Putting the IO in the third VLB slot and the video card in the second, leaving the first empty, seemed to be the best arrangement. And it left the IDE cables reasonably close to the drives, so that was a win. But once we got all the drivers loaded for that IO card and stuff, it absolutely flew. Ran rings around a lot of Pentium/90 systems because their 33MHz bus just couldn't keep up, and in the days before GPUs, pushing pixels into video RAM was a contest of raw bus bandwidth and very little else. We eventually had quite a lot of drives on that machine, so UDMA/33 moved a lot of bytes while still leaving spare bus cycles for overhead. I tried overclocking it to 50MHz a few times, and the IO and VGA cards were both capable, it was the RAM that shat itself. The upper 3MB of RAM would just vanish, leaving only 1MB, which was honestly a fair tradeoff for some things -- I'd boot in that config if I had a lot of PKZIP to do, or for rendering fractal graphics, which didn't use a lot of RAM but really appreciated the extra clock speed. Then clock it back down and reboot to use the results of those operations. Underclocking was also nice, and something I did frequently, so I could unplug the CPU fan and enjoy some quietude during a long BBS file transfer, which certainly didn't need much CPU grunt. The mobo clock generator didn't mind being re-jumpered while the system was on, and going from 40MHz to 16MHz (I think) was a simple matter of adding or removing one jumper cap, as I recall. I could reach through the floppy-drive opening in the front of the case and do this after a download started. Then switch off the monitor, and listen to the quiet tick-hiss of interference on my FM radio, which picked up just enough of WHYT 96.3 in the basement that I could listen to some alt-rock while also being aware of the UART ISR being hit. When the ticking stopped, the modem was idle, turn the monitor back on, jumper the CPU back up to speed and plug the CPU fan back in while the CRT warmed up, and get on with unpacking the file.

qbasic_forever 4y ago

Had an AST 486DX2/50 as my first PC in ~93 or so--I have a lot of good memories poking around DOS, playing Doom, tons of shareware, dialing BBSes (on a 2400 baud modem!) and more. It was a great machine.

mobilio 4y ago

I had DX/33 DX/50 and then DX2/66 plus DX4/120 I remember that before DX2/66 i wasn't seen on chip labels about "heatsinks". On DX2/66 there was label "heatsink required". But on DX4 label was "heatsink and fan required".

tecleandor 4y ago
And also "Peel this label before putting the heatsink". I know people left the sticker there... with consequences.
jeffbee 4y ago
Yeah people have forgotten this but when the Pentium came out and all Pentium PCs required a CPU fan, this was criticized by many reviewers. Now I have an Intel CPU with a motorcycle-sized radiator and a coolant pump :-|
- qbasic_forever 4y ago
  Such a silly criticism too since hard drives of the era were so obnoxiously loud.
- mmcgaha 4y ago
  I had a pentium 66 with just a huge heat sink. My pentium 133 had a fan but when I upgraded to a k6-2 I under clocked it so I could just use a heatsink. It was 2015 before I finally got another fanless computer.
hulitu 4y ago
I had an AST Cyrix 486 DX/2 66 without heatsink.

fsagx 4y ago

My first PC was a 486DX50 from the bargain bin (with no box or accessories) at Best Buy. I never had a fully new system again, as each newer configuration still had many parts of the old ones. Very Ship of Theseus.

NotYourLawyer 4y ago

This takes me back, although my first computer was a 486SX 25 MHz. At some point I inadvertently over locked it (long before I heard that word) because there was a jumper to change the bus from 25 to 33. I couldn’t believe it just… worked!

bluedino 4y ago

The 486 was such a massive improvement over the 386. And the DX2/66 felt like almost as big of an improvement over the 25/33MHz 486's. The 486 landscape was weird. You had crippled, 386-like versions such as the 486DLC/SLC, Intel's DX4's that hit 75 or 100MHz, and clones that went up to somewhere around 133MHz (by this time the Pentiums had hit the streets, so the 486's on steroids were for budget users). And they were often given similar sounding names to the 586, to further confuse buyers. It was amazing, and infuriating, to have your decently high-end system basically obsoleted in two generations. And, the DOS to Windows transition didn't help matters. It seems really odd in a time where you could still be using a 10 year old i7 and be just fine.

ido 4y ago
486DLC/SLC were not really "crippled versions", they were completely different CPU designs that used the 486 name as Intel wasn't able to stop other companies from using a number (one of the reasons for naming the next cpu family "pentium" which they could trademark/copyright). The crippled versions were the 486SXs, which disabled the FPU.
- dspillett 4y ago
  > The crippled versions were the 486SXs, which disabled the FPU. Though for many use cases at the time, that wasn't a massive issue. Many games didn't take advantage of the FPU until far into the 486 era, they were only starting to when the Pentium and its competitors came out (a killer for Cyrix's P5-era chips which despite a very strong integer performance had terrible floating-point umph). There were 487 FPU co-processors, to upgrade 486SXs, though unlike the 287 and 387 before them they weren't really co-processors, they were actually full 486 chips and the main CPU was disabled when they were present. The name caused confusion because SX in 386 meant something completely different (there was no built-in FPU to disable): a 16-bit data bus instead of 32-bit and 24-bit address bus, along with more minor changes, so it would work on cheaper motherboards originally designed with 286's in mind.
  - bluedino 4y ago

xenon2 4y ago

Very interesting article. On side note, I've had Am486Dx4VT8 (8 kb internal cache in WT mode). I was able to run it in 2x50MHz mode with Trident VLB card - it was my first "overclock" to have somewhat playable Quake experience (but not really).

newfie_bullet 4y ago

My first computer was an IBM EduQuest 486 SX/50 (https://www.ardent-tool.com/EduQuest/EduQuest_55.jpg https://www.ardent-tool.com/EduQuest/EduQuest_55.jpg) - great memories of taking that apart and learning about how things worked (glad my parents didn't know what was going on after spending $2000 on a computer for 'school work')

johnklos 4y ago

It was a very interesting time in computing history. The changes from the i80286 to the i80386 were extreme - the i386 gave us a fundamentally different instruction set that common 32 bit systems still use in 2023. On the other hand, the changes in the i80486 were purely about speed: relatively large built-in caches, integrated FPU, significantly better pipelining and so on. It was the last time Motorola really competed with Intel. The m68040 was all about performance, too, and Motorola's chip was faster in integer, floating point, synthetic and real world uses, clock for clock. (The m68060 was somewhat competitive with the Pentium, but people weren't choosing between x86 and m68k by then.) The x86 world really owes some thanks to Motorola for the competition. However, the fact that Intel was selling '486s like hotcakes meant they spent the time and money to continue to improve the '486, so the clocks went way up. The m68040 never had any clock improvements over 40 MHz. An i80486 system can still run NetBSD decently in 2023, which is a testament to the generally good performance of the CPU :)

chungy 4y ago
Intel pushed the 486 up to 100 MHz via the iDX4 chip (which lost the i486 branding, but it's still what it is). Initially intended for embedded systems, it was sold directly also to consumers with the "OverDrive" brand attached. (Maybe it was unsold stock from the embedded attempt?) AMD would further push its own 486 chips to 150 MHz, and I recall the raw clockspeed allowed it to stay competitive against the lower-end Pentiums (60-75 MHz), but architectural changes in the Pentium (branch prediction and out of order execution) really let the Pentium fly away from the 486 at fewer necessary cycles.
- mschaef 4y ago
  > Initially intended for embedded systems, it was sold directly also to consumers with the "OverDrive" brand attached. They also spent some effort marketing the DX4 as a low end alternative to the Pentium. It was possible to buy/build DX4 machines. Trouble there is the same as any other low end offering of the time - it got steamrolled by better technology coming down in price as quickly as it did. The window of opportunity for anything low end was not that large.
- 4y ago

balls187 4y ago

Our first PC was an AST Advantage 486dx/33 Purchased from the McChord AFB computer shop. Originally my dad wanted to “upgrade” our Amiga1000 to be PC compatible, but learned such a thing was not possible.

timbit42 4y ago
You could have upgraded to an Amiga 2000 and put a Bridgeboard in it or a third-party one with a 486 on it. You could even upgrade it to a Pentium Overdrive processor. The Amiga was also able to run Mac OS as a task on it's own "screen" alongside Workbench and other Amiga apps, so you could run Amiga, Mac and IBM PC software all at the same time at full speed.

tedunangst 4y ago

> It's possible that some operations, particularly those that involve memory- or disk-intensive access, may actually be slower with the DX2/66 than with the DX/33. Some things never change. The mechanical translation of "not faster than" to "slower than" is ever prevalent.

fabiensanglard 4y ago

Gorgeous article. - Topic close to my heart. - Loads of references at the bottom. - Oh my god, it even features the publication date at the top.

marttt 4y ago

Are there any moderately priced 486 SBCs available these days? The ones I've encountered (forgotten the links) were in the $200-or-so range. Surprisingly expensive, or not? I would love to have a dirt cheap fanless 486 minicomputer for FreeDOS (SvarDOS). Not for gaming, mostly for writing and some hobbyist coding. (I'm an ultra-slow thinker, so a single-tasking system is very probably plenty for most things. :) Currently thinking about this one, with Vortex86 -- but it is still, well, fairly expensive as compared to something like a RasPi: https://icop-shop.com/product/ebox-3100/ https://icop-shop.com/product/ebox-3100/ As for fanless and low spec, there is, of course, this wonderful table of thin clients: https://www.parkytowers.me.uk/thin/hware/hardware.shtml https://www.parkytowers.me.uk/thin/hware/hardware.shtml

tomatocracy 4y ago
Alternatively, a Raspberry pi 4 should be powerful enough to run PCem emulating a 486 class system I think.
- marttt 4y ago
  Sure, there are emulators, but I was thinking of a native system. Emulators seem to work great, but I try to avoid several layers of abstractions. Also, feeling nostalgic about how a native FreeDOS system boots in literally 2 seconds (on a modest laptop), I guess. Someone built this: https://www.youtube.com/watch?v=ZBsv-jRiIT8 https://www.youtube.com/watch?v=ZBsv-jRiIT8 And this, the weeCee; the price point estimated in the comments is around $600, though: https://www.youtube.com/watch?v=USHvvSbYmJA https://www.youtube.com/watch?v=USHvvSbYmJA A third one, with lots of diy involved: https://github.com/eivindbohler/tinyllama https://github.com/eivindbohler/tinyllama It is interesting nonetheless that really-low-spec SBCs have not gone into the masses (thus resulting in dirt-cheap prices) the way the RPis have. It is still a nice dream to see this happening with the current rise of retrocomputing.