Does it make sense to swap those CPUs?

[@danielktdoranie]

Leave it as it is

[@robertrose3905]

Leave it as is, seems like a decent little board that is working well.

[@stamasd8500]

Good choice, don't swap the CPUs. You will end up with 2 non-working boards.

[@bitsundbolts]

Oh, I spent way too much time on these boards to end up with two non-working boards 😅

[@dolphhandcreme]

I swapped i386SX to 486SXLC2... even when running at 5V (the SXLC2 is 3.3V) it works. Needs good cooling though. Gain is immense.

[@bitsundbolts]

I think the tolerance back then was a lot higher. I've read the same. If you run the clock-doubled CPU at 5v, cooling is important.

[@simonscott1121]

Leave the CPUs alone!

[@bitsundbolts]

Yeah, you're probably right!

[@Dinnye01]

This is a super interesting premise. I mean there is value in testing this out for the rest of us! Lovely work!

[@bitsundbolts]

I'll try to get a 486slc and then replace the 386sx.

[@Dinnye01]

@@bitsundbolts Will be here to see the results! My retro enthuisiasm is cornered into Logisim Evolution (and a bunch of FPGA-s), but it is always awesome to see someone having their hands on original hardware and doing right by it. In fact, the first video that youtube recommended from you was under a video from Ben Eater. Checking out your channel, I knew I was in for a treat. So, whatever you may decide to do, I'll hop on for the ride! Viel Glück!

[@frtls]

Leave Britney alone! I mean the cpu, leave the cpu alone!

[@Constantin314]

as someone famous use to say... "computer says noo"

[@T3hBeowulf]

I enjoyed the video and while my normal philosophy is "If it ain't broke, take it apart and fix it." but in this case, I don't think the CPUs should be swapped. The different signalling pins tells me they're different CPUs and I fear that might cause more harm than good.

[@bitsundbolts]

Yes, i think the same. The BIOS might also be specifically adapted for the 'cyrix cache'. It might set some registers that aren't activated by the other BIOS.

[@Melechtna]

Brain had a literal loading error when I began processing this motherboard...where is....EVERYTHING?!

[@michaelturner2806]

I would say leave as-is. If you're curious about the cache related pins, see if you can trace where they go on another board that has them with the main chipset, and possibly risk frying something by putting in bodge wires. Or after you remove the sticker maybe there will be a data sheet for the chipset that would tell you / confirm where cache lines would connect, or if it'll confirm they're optional and not needed.

[@M0UAW_IO83]

They're pin compatible and were a common upgrade/swapout. BIOS might not make the most of it but it should be fine. Reference, I used to repair PC motherboards for a living and did that swap quite a few times for myself and colleagues as an upgrade.

[@bitsundbolts]

Oh, that's interesting! Thanks for sharing this detail. But I guess I'll wait if I can just find a 486slc. I'd rather not ruin that board which seems to work now.

[@awilliams1701]

I almost feel like if it's connected, but not electrically, your best bet is to remove it (I know, that's a lot of work), clean it up, and then put it back. That gets rid of any last bits of nastyness.

[@alvaroacwellan9051]

I wouldn't swap the CPUs. It's apparently working the way it is, any further operations would just pose extra risk. I think. On the other hand, please try comparing its speed with 2 and 4 memory modules, I have at least one 386SX board that performs considerably better with four sticks. Maybe it does some interleaving when it accesses the memory.

[@sethalexander423]

That 1 pin looked to be frustrating to solder.

[@djdoo]

I would leave them as they are and put 2 coprocessors in the square sockets for completion. I would also remove that ugly toshiba sticker. Greetings from Greece, Keep up!

[@bitsundbolts]

That sticker will come off in the next video. I need to see what chipset is hiding underneath 😅 thanks for watching!

[@SianaGearz]

It's beautiful in how there's nothing on the board, like you could sneeze out a design like that in barely a few hours. Wait Doom (official release) in real mode is not a thing at all. It's got a 32-bit DOS extender, DOS4GW, which is effectively a single-process protected mode operating system. Some clones of EMM386 have DPMI built-in so they supplant that kernel in the DOS Extender, but the MS-DOS one does not.

[@bitsundbolts]

Right! I forgot about DOS4GW. Well, I tried to reproduce the issue, but it looks like my board works either way (ahm... Except for a few issues, but that's for a future video).

[@revelationnow]

I think those two pins on the AMD chip (29/30) aren;t connected on that CPU. Its only the 386SXLV variant, which is a low voltage embedded variant with a high priority system management interrupt which presumably puts it in and out of low power or standby mode.

[@bitsundbolts]

I'm really confused with the pin outs of these CPUs shouldn't they be identical? I always thought those 486slc CPUs were drop-in replacements. Unused pins are fine, then they won't use a specific feature, but different signals will be a problem.

[@revelationnow]

@@bitsundbolts Yeah, me too! I suppose given a lot of these are active low it means they are basically 'reserved'/NC pins on the 386 package standard for future features and will work without additional circuitry. I would have to assume that the 386 BIOS needs to identify the processor before it presents those extra features, and has to assume that the pins are actually physically connected on that board. The only thing is that if there is no circuitry on those feature pins, they may not actually go low since they are floating. I'm sure Cyrix must have allowed for this.

[@Ale.K7]

My vote is for leaving the boards and CPUs as they are :-)

[@bitsundbolts]

That's probably what I'll do - nothing 😂

[@Firebird_TV]

The pin-out says ...no! - Great video as usual. I am interested to know your method for capturing video footage when in boot screen and BIOS display.

[@bitsundbolts]

Yes, I think the pin out of those CPUs is too different surprisingly - shouldn't the 486SLC be a drop-in replacement? I use an OSSC connected to a very cheap USB capture USB Stick. VGA -> OSSC -> HDMI -> USB capture -> OBS. Surprisingly, expensive solutions like the elgato Cam Link don't work with those odd resolutions under DOS and BIOS.

[@SianaGearz]

The pinout doesn't say you can't just lift a couple pins!

[@samuraidriver4x4]

Leave as is. There is always a chance you damage something beyond repair. Also those pins really didn't want to take that solder.😮

[@borlibaer]

Peace 🖖🐻✌️

[@drgusman]

According to the datasheet KEN is optional because it has an internal pull-up, but KEN is active low, soooo... according to that the cache is disabled. What if you try to tie pin 29 to ground?

[@knightsun2920]

One video idea I would love to see is a Voodoo 2 with 8MB per TMU? If it works maybeee a 40 MB SLI and see if it makes sense to do so.

[@GGigabiteM]

The Voodoo2 TMU can support up to 16 MB according to documents. I've never seen such a card in the wild though. You could technically have up to 36 MB on a single card (4 MB FBI + 16MB TMU + 16 MB TMU.) Combining two cards in SLI doesn't double the effective memory, both cards have to render the same data on alternating scan lines. It really wouldn't be worth it though, you'd have the same problem as the Voodoo1 with 6 or 8 MB of RAM, you run out of horsepower. Sure a Voodoo1 with 8 MB can run at 800x600, but it is painfully slow. The same would be the case with the Voodoo2. You don't gain any extra resolution due to the limited FBI memory, but the card having to push around more texture data is going to slow it down significantly. The easiest card to try it on would be the late Voodoo2 variants with 1 MB memory chips on one side of the card, with the back side not populated. At the very least, it'd give you somewhere to mount the memory chips without having to stack them.

[@bitsundbolts]

It's a nice idea, but it's odd that nobody has tried that yet. If it would be possible, then I would assume there would be an attempt already. There are these Voodoo 2 cards with 12 x 1MB memory chips. I'm sure, someone tried 20 x 1MB for the 8+8+4 (FBI). If that would be possible, I'm sure there would be at least a forum post somewhere.

[@knightsun2920]

@@GGigabiteM Probably correct, I am curious if it was a numbers game. The new VooDoo 3 having just 16 MB and cheaper last gen card having apparently more ram at 20MB. I would love to try 1024x768, though don't know if they work after all these years. I have two unmatched late VooDoo2 cards that have unpopulated pads.

[@knightsun2920]

@@bitsundbolts I am curious if it was just a numbers game as 20 MB is more than 16 found on newer Voodoo3 cards. maybe nobody has thought of it. You are good at fixing dead hardware. For example the RTX 4060 8GB vs the 16 GB debate. Could a SLI VooDoo2 20MB cards be faster than a single VooDoo3?

[@GGigabiteM]

@@knightsun2920 3dfx was such a mess by 1998, who knows. I think they cared more about trying to stay relevant when they were falling farther and farther behind Nvidia and ATI because of their mismanagement and STB merger. You can run mismatched V2 cards in SLI with a few tricks, though it'd be easier to just solder on the missing memory chips on the lower card, if you can source them. 100 MHz EDO memory was pretty rare, even at the time. Most everyone had switched to SDRAM. You can still find the older 60 MHz stuff for V1 cards and other cards that used said memory, but the higher clocked stuff not so much. Usually you have to rob another dead V2 card to get chips.

[@danielleblanc5923]

I am almost sure the there is a way to activate the Cyrix cache through software. There should even be a DOS utility for this purpose. In that case the Ken is optional.

[@bitsundbolts]

Yes, it looks like many things can be controlled via registers. With the correct DOS tool, one should be able to control those features - including the cache.

[@RoyHess666]

Leave as is Never change a running system!

[@bitsundbolts]

Yes! 👍

[@matthewday7565]

Do you have a clipover that you could try?

[@bitsundbolts]

Unfortunately no

[@mrsvcd]

I have the same board. Mine is equipped with a Am386-40

[@bitsundbolts]

Nice! Do you have the Cyrix cache Option in the BIOS?

[@ruben_balea]

Leave it as is, not every board has to be able to run DOOM, try LOOM instead, it's a great game, even a pirate from Monkey Island tells you to play it... well, the pirate actually tells you to *buy* it, but if you buy it it will be because you are going to play it, right? 🤔A pirate telling you to *buy it* instead of telling you to borrow it from someone to make a copy? I think I've discovered the secret of Monkey Island, that guy wasn't a pirate! 😁

[@WooShell]

Why are you missing 256k to the full 16M RAM? The board doesn't have any onboard VGA that would steal some memory..

[@blooder81]

i have dat305 rev b1 with cyrix cx486slc2 50mhz. got very bad battery leak like it as a burned negative point and some isa contacts

[@bitsundbolts]

Ehh, battery damage is always bad :( hopefully you can do something about it.

[@blooder81]

@@bitsundbolts also that idea to transplant to another similar board if i could find one and someone that could solder it.

[@o9p0]

i very curious about cpu swap but get the cpu from a new dead motherboard.

[@krzysztofb9279]

you should make an interposer then swap cpus

[@bitsundbolts]

Maybe one day. Depends how often I'll deal with those CPUs.

[@Neksus-M06]

Peel off the chipset's sticker. Might find a SARC. That points to asking Deksor for some help.

[@stamasd8500]

It is a SARC. Check retroweb under M396F ver 2.6. The actual chipset is listed there.

[@bitsundbolts]

That's probably what is under that sticker. I'm still a bit surprised by the Toshiba branding - was this board possibly in a Toshiba PC?

[@Neksus-M06]

@@bitsundbolts Being PC Chips behind it could be whatever. No datasheets are available for that chipset. I've been looking for boards supporting this cpu and I couldn't find one (my mistake on TRW - probably don't know how to search). Well, there must be known and documented chipsets that support this cpu natively.

[@joebruno2675]

Leave it as it is with no swap. Build something cool with the small board tho.

[@Mr_Meowingtons]

it has pins for a socket you can just poop a socket on and use whatever..

[@666KoXz666]

swap :) what can go wrong :))

[@bitsundbolts]

Haha. Famous last words 😂

[@ricardodm9241]

great! Your restoration work is very good, congratulations!! With knowledge and certainty, I can say that you made the right choice! DO NOT REPLACE! I would like to tell you that COMPATiBiLiTy is NOT just about seeing pins with the SAME functions (same labels). the two could have the same pins, BUT, have different timings... Have you ever noticed that some trails make a zig-zag path before reaching their destinations!! These zig-zags are there to complement the latencies of the tracks and ensure that all signals from a given bus (such as the data bus) arrive at the same instant. These characteristics may change from one manufacturer/type to another. you did the right thing, congratulations!! and once again, excellent work restoring/recovering a CPU board 😉

[@bitsundbolts]

Yes, I've seen those zigzag traces. I think it's best to leave the CPUs on their respective boards. There are better things to do than swapping the CPUs.

[@tsclly2377]

leave the CPU and add a Co-Processor

[@bennetb01]

Swap for science. Are these cpu's able to be socketed?

[@AnnaVannieuwenhuyse]

I believe sockets did exist for this flat pack form factor, but for my QFP's I have always soldered them to a QFP-to-THT interposer which is much more commonly socketed in of itself.

[@bitsundbolts]

Maybe I'll find another CPU that I can use for the 386SX board in the future. Since the 486slc board works and has the dedicated 'cyrix cache' option, I don't want to take it away.

[@1kreature]

Why has PCBWay introduced gambling. That really irks me.

[@bitsundbolts]

Don't worry, you'll never win 😂

[@xephorce]

leave it you should only change it if its broken or you have an upgrade for it lol.

[@Foxtrot_Foxtrot_Lima]

Does it make sense to watch a 26 minute video for nothing? Does it make sense to stay subscribed to someone who wastes me time? NO!

[@SleakaJ]

Leave the CPUs as is.

[@bitsundbolts]

Yeah, I think so

[@Qyngali]

Why would you even consider swapping the CPUs when the pinouts aree commpleetely different.

[@bitsundbolts]

Initially, I thought the cache doesn't work on the 486slc board. But that clearly works. And the other reason was, as you said, the pin outs don't match.

[@Popclone]

You only lose is time, but do you think you will fry it if you try ? Otherwise you will just have to move it back. Whats the point of stocking up on boards ? What about the Universal BIOS can you upgrade the BIOS on it and maybe the L1 cache option will displaying ? Don't listen to the people bellow they don't know how to burn boards MUHAHAHAHA

[@Marsandrey]

SWAP IT!!! Please. Anyway, the board is from garbage

[@bitsundbolts]

I have two more videos to make with that board. By then, I might have a CPU I can use to replace the 386sx

[@toseltreps1101]

Luschdig wie du immer zwischen langsamer Nicht-Skript-Stimme und Doubletimesponsorsprech wechselst 😄

[@bitsundbolts]

Ja, das Video war etwas durcheinander. Es hätte eigentlich ein Swap werden sollen, aber dann gab's Problem und die Datenblätter haben keinen Sinn gemacht.