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cr1901
February 25th, 2014, 12:44 PM
Technically, this is a "service" that I'm asking for, but I can reach more people by using this subforum. THat being said, moderators please feel free to move the post if it truly belongs in the "Services" forum.

Some time ago, I did an experiment comparing multiple PC and XT-class BIOSes to determine how similar they are in the mess of a thread called "Fun with BIOS programming". The TLDR conclusion is: A surprising amount of backwards compatibility with data structures and entry points with the original 5150 BIOS was kept, even up to 486-class boards. More recently, I'm starting to question just how important the backwards compatibility is in practice, even back when XT-class PCs were relevant. I wish to do another binary comparison and analyze more BIOSes this time, and see whether I can find any significant "deviations" from IBM compatibility, as well as just compare how their routines/data structures are set up in general.

I have attached a BIOSDUMP utility- just include a filename on the command line, and it will dump segment 0F000h to a file for you. I'm in particular looking for PC/XT clones, but I'd appreciate anyone who is willing to dump their BIOS using this program, and attach it here (how you get it from your XT,AT,etc to here is up to you :P). I tried running the utility in DOSBOX successfully, so it should work on real machines.

If I can find any significantly different BIOSes, what I'll most likely do next is see if I can find some software which try to call BIOS entry points directly and not use interrupts, and test them in a PC emulator running said BIOS.

Chuck(G)
February 25th, 2014, 01:00 PM
Doesn't someone on this forum already maintain a collection of BIOSes?

cr1901
February 25th, 2014, 01:10 PM
If you mean modem7- I already analyzed his collection/contributed to it. :P Most of them are similar.

Why don't you dump some of your clones? Long ago you offered to send me what you have, but real life got in the way and you never got around to it?

Trixter
February 25th, 2014, 01:32 PM
A surprising amount of backwards compatibility with data structures and entry points with the original 5150 BIOS was kept, even up to 486-class boards. More recently, I'm starting to question just how important the backwards compatibility is in practice, even back when XT-class PCs were relevant.

In my archival work, I've found a non-trivial number of games written before 1984 that directly call routines in the ROM, or revector interrupts to code in ROM, or similar. Half of these are loaders or protection routines, and the other half do this in-game as a normal practice to shave a few cycles here and there.

cr1901
February 25th, 2014, 01:38 PM
In my archival work, I've found a non-trivial number of games written before 1984 that directly call routines in the ROM, or revector interrupts to code in ROM, or similar. Half of these are loaders or protection routines, and the other half do this in-game as a normal practice to shave a few cycles here and there.

Do you have a list of such games? If yes, could you do me a favor and post it into the "Fun with BIOS" thread? At least one other person was asking about the entry point compatibility, and I mainly made this thread for maximum exposure from VCF members/post their BIOS images, not as a continuation of that thread.

Trixter
February 25th, 2014, 01:58 PM
I don't have a list, but if I create one I will be sure to post it there. The list wouldn't do you much good through -- most of these games are showing up in my archival work because they are incredibly difficult to crack which is why they're not floating around to examine. In fact, part of cracking them involves removing or rerouting as much BIOS-pointing-tomfoolery as possible, so obtaining the cracked version won't help you.

If you want to try anyway, then enjoy trying to slog through this mess: ftp://ftp.oldskool.org/pub/misc/temp/OptionBoardTestImages/DOB/TransCopy5.4/NSTALKER.IMG
It's a protected Deluxe Option Board Transcopy v5.4 image of Mattel's Night Stalker.

Chuck(G)
February 25th, 2014, 04:29 PM
If you mean modem7- I already analyzed his collection/contributed to it. :P Most of them are similar.

Why don't you dump some of your clones? Long ago you offered to send me what you have, but real life got in the way and you never got around to it?

To be blunt, what's in it for me? That means hauling machines out of mothballs, dumping BIOSes, uploading them--for what? This is all old stuff to me--and most pre-386 BIOSes look pretty much the same to me.

cr1901
February 25th, 2014, 04:54 PM
To be blunt, what's in it for me? That means hauling machines out of mothballs, dumping BIOSes, uploading them--for what? This is all old stuff to me--and most pre-386 BIOSes look pretty much the same to me.Is that not part of the charm of the hobby? And I personally don't think 286 BIOSes look the same (American Megatrends and AWARD comes to mind). XT clones, yes, to a much greater extent.

I don't know what's in it for you, other than at least the ROMs are preserved in case someone needs them. I could consider bribing you for your services though ;).

I just remember you saying that you were willing to do it some time ago (early 2012- I made a thread asking about BIOS Revisions for the AT or something like that), and then when I PM'ed you regarding it a few weeks later (God knows why I waited), you told me "real life was in the way and it would take a while"... and you never did it. I PM'ed you since last July asking if you'd be willing to try again, but got no response.

Real life gets in the way. I get that. I was under the impression you had easy access to your images (i.e. they were dumped, just needed to be found), or that it wouldn't be that much of a time commitment.

I would be happy to check and find the old threads if you don't believe me. Presumably you test your old machines once in a while- do it when you test! In any case, perhaps asking for this was a mistake, since there's been 0 downloads/no interest... I just simply cannot afford (in terms of cost or space) more clone boards right now.

SomeGuy
February 25th, 2014, 04:56 PM
17478
Here is an "Ethom Atlanta" BIOS that I dumped from a generic Taiwanese XT clone. I had sent that with some other 286 and card BIOSes to Modem7, but I guess he hasn't done anything with those those yet.

Weird thing about those "Tubo XT" type generic Taiwanese boards is that although they were almost identical, they always seemed to have a wide variety of crappy bioses. Back in the day, I would usually rip those out and plug in a good Phoenix bios.

Now the proprietary ones, those really need archiving. I would love to get my hands on a newer bios for my CDP MPC 1600 to see if I could get VGA working.

Chuck(G)
February 25th, 2014, 08:34 PM
I probably did say that and I still may. But it's going to be a lot of work--something that I can't justify right now.

Most of the clone BIOSes were based on the ERSO/DTK version at any rate. There is very little substantial difference between them--not at all like later 386-era machines with LSI chipsets.

But if you want to return a favor, find me a Durango Poppy PC--that has meaning to me. All the rest of this stuff is just that--stuff, more or less the same.

Trixter
February 26th, 2014, 07:33 AM
find me a Durango Poppy PC--that has meaning to me.

Well, you're going to have to explain that little nugget. Nostalgia? Your design? Fond memories?

Chuck(G)
February 26th, 2014, 08:11 AM
Well, you're going to have to explain that little nugget. Nostalgia? Your design? Fond memories?

Member of the project team. I still have quite a number of the (handwritten) design documents. As far as I know, it may be the first 80286+80186 system. Normally ran Xenix, but could also run MS-DOS. One of the oft-neglected "not quite PC compatibles". I actually lobbied for, and got plenty of support to use the 68K instead, but Bill Davidow was on the board of directors and threw his weight around a bit...