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BIOS Swap or Upgrade? Pheonix 80386

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SpidersWeb

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Hey guys,

Just a real quick question.

Have a 386SX-20 with a Pheonix BIOS but the features are pretty bland to say the least.
Can I fit an AMI-BIOS from another 386SX? or upgrade the Phoenix to one which lets me change the parameters for types 46 and 47 - or is there a software tool that can do this on the old Phoenix 80386 BIOS?

(Motherboard is plain jane, nothing fancy, except it doesn't use SIMMs, just 2Mb on-board of 41256 chips).
 
Typically, yes, you can swap BIOS's on early PCs, doesn't work as well with past 486 PCs because of different board makers implementing different features in the chipsets, but if they are similar enough even then it can work. 386 and older its usually pretty interchangeable, Phoenix, AMI, Compaq, all pretty universal.

I would suggest you keep the original BIOS chips with the PC, some collectors would want a PC original, so you will want to be able to restore it back to stock.
 
For generic chipsets maybe but how well would it work for NEAT based boards for example. Did they sell custom BIOS to each board maker or did they do a one size fits all BIOS?
 
RWallmow said:
Typically, yes, you can swap BIOS's on early PCs, doesn't work as well with past 486 PCs because of different board makers implementing different features in the chipsets, but if they are similar enough even then it can work. 386 and older its usually pretty interchangeable, Phoenix, AMI, Compaq, all pretty universal.

I would suggest you keep the original BIOS chips with the PC, some collectors would want a PC original, so you will want to be able to restore it back to stock.
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Cheers, I'll keep the originals just as backups anyway but this machine wasn't terribly original - one of those machines where the owners just slapped stuff together. Motherboard is some generic brand, rusty case is from a TURBO XT.

BIOS works, but wont let me edit the values for type 46 or 47, they're just blank :/ As it's a bit of a go-between box, I'd like to be able to enter those numbers for testing etc straight from the ROM.

Have some ROM gear on the way, so if I can find some better BIOS images that are suitable in size, I'll give that a whirl on a fresh chip.
 
Careful. I have a plain-jane 386/20 and the AT-full-size motherboard is fully crammed with SSI support logic--so much so, that the memory is on a separate card. This has no LSI chipset.

I'm guessing that you have someone's LSI chipset on the board--and some of those required custom setup code. Some of those required special setup code.

My answer to your question would be--maybe.
 
Swapping out the BIOS isn't really a good idea. Even if you have one from a board with the exact same chipset, there were often little differences "behind the scenes," so to speak, that will cause strange issues even if it appears to work. Also, when you try to go to a different BIOS manufacturer, you usually can't just swap out the BIOS chips themselves, you need to get the keyboard controller chip as well... and I don't know how universal those are, so I wouldn't just go blindly swapping 'em around.

I honestly think your efforts would really be better spent elsewhere. There were a fair number of IDE cards with their own boot ROM, that would be a better option than anything you'd gain from switching to an AMI BIOS, which is still going to be pretty limited... BIOSes back then just didn't have a whole lot of options. Alternately, there's an AT version of the XTIDE Universal BIOS, so if you have any sort of add-in card with a socket for a boot ROM (even an ethernet card would probably work), you could go that route.
 
Old Thrashbarg said:
Swapping out the BIOS isn't really a good idea. Even if you have one from a board with the exact same chipset, there were often little differences "behind the scenes," so to speak, that will cause strange issues even if it appears to work. Also, when you try to go to a different BIOS manufacturer, you usually can't just swap out the BIOS chips themselves, you need to get the keyboard controller chip as well... and I don't know how universal those are, so I wouldn't just go blindly swapping 'em around.

I honestly think your efforts would really be better spent elsewhere. There were a fair number of IDE cards with their own boot ROM, that would be a better option than anything you'd gain from switching to an AMI BIOS, which is still going to be pretty limited... BIOSes back then just didn't have a whole lot of options. Alternately, there's an AT version of the XTIDE Universal BIOS, so if you have any sort of add-in card with a socket for a boot ROM (even an ethernet card would probably work), you could go that route.
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I wasn't aware of that AT boot ROM, that sounds like a much better solution. There will definately be an ethernet card with a spare ROM socket.
I wonder if I could do the same thing to my T5200/100 (likely so) when it's drive is changed to an unsupported model (rather than hacking the factory BIOS).

The 'AMI-BIOS' thing was because I had a 386SX/16 when I was younger with an AMI-BIOS - it let me set hard disk types manually and even low level format - but this Pheonix BIOS on this 386SX/20 is a single page with very few options - both boards were the same age. But your AT IDE ROM solution sounds like the business anywho so I'll go investigate that.

Also have BIOS 'disagreements' with my Concord XT286, but can't really ask about that until I've done more testing to be exactly sure where the problem is. It's a weird setup because you've got an XT clone board with a 286 CPU and 1024Kb of RAM and a special DiskCache BIOS written by PerformancePCs in 1986.

Edit: just spotted that universal BIOS also supports > 504Mb, I wasn't even going to ask if that was possible because I thought that'd be pushing my luck!!! Finding 1-8Gb drives is way easier.
 
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Actually, the XTIDE Universal BIOS will work with disks much, much bigger than 8GB - until a couple of weeks ago, I was using a brand new Western Digital 320GB drive on my 286 with XTIDE hosted in a 3Com 3C509B. Yes, you can only use the first 8GB, but I'd rather do that than use a second hand drive of unknown reliability.
 
If it's a 386, my question would be "Define Bland" -- since apart from setting date/time/drive types just what are you expecting out of it?
 
I'd like to be able to set the custom drive types (for larger IDE drives that don't have a type), and being able to low level would be handy (but not necessary) so I can use it to prime MFM drives quickly etc.

The AT BIOS from the XT-IDE project sounds like it'll sort out my drive type issue completely though.

My options are basically floppy types, the time, hard disc types (but can't type in custom values??), CPU default speed (Low or High), memory quanitity,display type - not much else. I'm probably being picky, I just remember my 386SX growing up with it's AMI BIOS and what options/tools it had built in.
 
Cheers for that, yep I knew about anydrive but wanted to avoid 'hard disk configuration errors' on start which this BIOS definately throws.
Still waiting on ROM burner from China :/ Thankfully have enough other little vintage projects to keep me busy.

Out of curiousity, is there a tool that'll autodetect an IDE drive on another channel and mount it in DOS (after booting)?
Similar to how CDROMs worked in DOS with MSCDEX.
 
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I wouldn't mess with the BIOS as you may run into some 'chipset' problems down the line. If it were me, I'd opt for a SIIG (or similar) ISA IDE controller. That would be a cheap way to and they are fairly plentiful, without busting the bank. That's the route I've taken on my 286's and 486's and it works for me.
 
SpidersWeb said:
Out of curiousity, is there a tool that'll autodetect an IDE drive on another channel and mount it in DOS (after booting)?
Similar to how CDROMs worked in DOS with MSCDEX.
Click to expand...

There are drivers that detect various drives attached to the paralell port, one of them is the Addonics PHD drivers package. I'm not familiar with any drivers that can detect an IDE connected to an internal card such as a CD card. There have been success stories of running the XT-IDE BIOS from a network card by replacing the BIOS chip on the network card with the XT-IDE BIOS. That allows the XT-IDE BIOS to load and then detects drives attached to the system via cards such as an old CD card, that's if I understood what I read.
 
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Cheers for that.
Yeah I'd found success stories from people that had a BIOS with 4 entries, or XT-IDE, was just wondering if I could get away with it after DOS had already loaded ;) Haven't heard anything and I definately can't find anything on the net, but I can understand it being a pretty weird reason to sit down and write software, so not too suprised.

Can't wait to get my ROM burner and start using the AT version of the XT-IDE BIOS. Going to make hard drive options so much simpler (will be using network card ROM slots).
 
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