BIOS HACK: booting in 15KHz

[Driver-Man]

The message body was left empty.

[Howard_Casto]

Nice find. 

I think you might get more of a response if you would go into more detail about how this would be useful.  I personally can't think of much use for it. 

If you are running dos there are several tsr's, front ends and mame builds that will get you to arcade frequencies.  If you are running windows then bios settings wouldn't have any baring on teh resolution displayed in windows (or would it?).  And of course linux makes it easy to change video card frequencies. 

What did you intend to use this for?

[Driver-Man]

This, in particular, is for the first 5-10 seconds when the PC powers up - BIOS POST. Before DOS/WIN can do anything about the resolution. They say some arcade monitors/tv can be damaged with this too high (wrong) sync frequency, so the usefulness of this would be to protect your monitor/tv, beside aesthetic reasons as it also make machine appear more authentic, or "less of a PC", so to say.

I also made a TSR version for use under DOS with emulators and front-ends that do not support 15khz monitors/tvs, but if you already have a program that does that for you than there is no other benefit here except that my code is probably the smallest of all, thus most suitable for BIOS patching.

[jimmy2x2x]

Nice idea, but I think a lot of people will be hesitant about patching bios files then flashing the file.  Very easy to brick a system, and not always easy to recover from that situation.

[Driver-Man]

Well, kind of, but consider...

All you need is two "similar" old PCs to insure you will always be able to return to working version of BIOS. I'm doing this on my 5 old PCs around 133-233MHz, all with Award BIOS 4.51, size 128Kb, and I can burn any BIOS from any of those boards on any other of those mother-boards.

So, if you already have, or can buy cheaply, couple of old PCs with the same size and version of BIOS than I highly recommend this as a cheap and fun project. You can probably get two old PCs for about $10-$30, if not for free. 133MHz PCs can play many vertical (older) games at 100% and more, so that investment may be not only worthwhile for various tasting and hacking purposes, but also as a good side "60-in-1 game board". If you have Award BIOS 4.51 (128kb) then I can guarantee successful patching by providing all the necessary tools and fool-proof, step-by-step instructions. -- Also, how much does your arcade monitor cost? Is it worth doing something about those 5-10sec of BIOS POST, would that make it last longer? (Actually, I think that's "urban legend", I don't think anything can happen to monitor, so I'm doing this mostly because it's cool, and I have all these old computers to play with.)

[XNIF]

Thank you for your post. I was wondering the same thing, good to see someone tried it!

I think wrong voltage on scart connectors with a VGA -> scart connector cable  (without the capacitator) can damage the monitor/tv but a wrong resolution i dunno.
But isn't it cooler not to see the bios boot , and instead booting in a hidden windows frontend?

[Howard_Casto]

The whole thing about the wrong frequency damaging a monitor is sort of a myth.  I even believed it once upon a time.  You aren't changing the voltage or amperage of the signal, you are just altering the rate of speed, so in theory at least, it shouldn't damage your monitor at all, it will just be unable to keep up and thus you'll get garbage on the screen.  Personally I prefer this.... looks like the typical bootup of a classic machine.

I can certainly see the benefit of being able to read the bios menu when you are tweakign things though. 

[Driver-Man]

I disagree about the "screen garbage". Monitor being off sync and having garbled video memory are two completely different types of "garbage". What original games did is that they, most likely, were using video memory as temporary storage to decompress graphics, so whatever went there got on the screen automatically. The point is that the original PCBs would sync the monitor the very instant they power up, and that "garbage" was actually 'graphics' on a perfectly stable picture. -- Anyway, I suppose if your PC can get from power-up to DOS/WIN logo in less than 5sec than this makes not much difference as the monitor probably needs that much time to warm up and show anything at all anyway.
 
By the way, I have 450-in-1 board imported from China, it uses advanceMAME and ArcadeOS, it boots in DOS and they did not do anything about out-of-sync boot, they probably just changed text color of BIOS so it's all black, but still it's clearly out of sync. Funny thing, they left keyboard port on that PC.


XNIF,
But you can see it, even though out of sync you can still see some PC is booting up. I can even read most of it, especially at the 1st screen (with memory test) which just gets split horizontally but still with good vertical sync. -- Yes, I think it is better not to see BIOS boot. The thing is, once you know how to patch BIOS with 15khz driver, then replacing POST messages with your own or none at all would be easy thing to do.

[Howard_Casto]

I disagree about the "screen garbage". Monitor being off sync and having garbled video memory are two completely different types of "garbage". What original games did is that they, most likely, were using video memory as temporary storage to decompress graphics, so whatever went there got on the screen automatically. The point is that the original PCBs would sync the monitor the very instant they power up, and that "garbage" was actually 'graphics' on a perfectly stable picture. -- Anyway, I suppose if your PC can get from power-up to DOS/WIN logo in less than 5sec than this makes not much difference as the monitor probably needs that much time to warm up and show anything at all anyway.
 
By the way, I have 450-in-1 board imported from China, it uses advanceMAME and ArcadeOS, it boots in DOS and they did not do anything about out-of-sync boot, they probably just changed text color of BIOS so it's all black, but still it's clearly out of sync. Funny thing, they left keyboard port on that PC.


XNIF,
But you can see it, even though out of sync you can still see some PC is booting up. I can even read most of it, especially at the 1st screen (with memory test) which just gets split horizontally but still with good vertical sync. -- Yes, I think it is better not to see BIOS boot. The thing is, once you know how to patch BIOS with 15khz driver, then replacing POST messages with your own or none at all would be easy thing to do.

No, older games were doing a self check of their video ram, that was the grabage.  But I didn't mean that it looked exactly the same, I meant that it reminds me of an old bootup. 

What computers are you using exactly, because my experiences are quite different.  First off, I've turned all the post tests off, so my bios virtually isn't seen. Secondly I can't make out the bios screen at all.  It just looks like lines of color.  Plus as you said, from a cold boot a arcade monitor takes quite a while to warm up.  I'm usually in arcadeos by the time it's actually on. 

Now what you are saying about changing the post messages is definately promising, but like the others I have concerns about bricking the pc doing that. 

I think your suggestion of using the code as a more effecient tsr makes a lot of sense though. 

Not complaining btw.... just having a dialog. 

[Driver-Man]

I agree there is a line where this hack becomes less useful, or noticeable at all for that matter.

I am using this on my old 133-233mhz PCs. It takes good 10 seconds for them to boot, so I much prefer this. Plus, it is not so hard to hack BIOS, nor risky. Many people hacked their BIOS to change EPA logos and put full-screen images during POST, and what not.  -- I do not suggest anyone goes on and hack their primary computer. First find some old computers in your basement and once you feel more confident you can do it on your main machine. And again, you can insure from fatal mistakes by having two computers with compatible bios.

[Marsupial]

netiquette...

An "Internet troll" or "Forum Troll" or "Message Board Troll" is a person who posts outrageous message to bait people to answer. Forum Troll delights in sowing discord on the forums.  A troll is someone who inspires flaming rhetoric, someone who is purposely provoking and pulling people into flaming discussion.  Flaming discussions usually end with name calling and a flame war.
 
A classic troll is trying to make us believe that he is a genuine skeptic with no hidden agenda.  He is divisive and argumentative with need-to-be-right attitude, "searching for the truth",  flaming discussion, and sometimes insulting people or provoking people to insult him.  Troll is usually an expert in reusing the same words of its opponents and in turning it against them.

They usually have an agenda. Very few trolls come to out of pure skepticism. A Troll is generally a person who is extremely skeptical of the main forum subject.
He is generally interested to make other forum members look stupid. A troll will sometimes use insults to provoke other people to insult him. Then, he will complain to moderators of being insulted and will request that his opponents get banned from further discussion.

He (and in 90% of cases it is he) tries to start arguments and upset people.

Sometimes, Internet troll is trying to spin conflicting information, is questioning in an insincere manner, flaming discussion, insulting people, turning people against each other, harassing forum members,  ignoring warnings from forum moderators.

Trolling is a form of harassment that can take over a discussion. Well meaning defenders can create chaos by responding to trolls. The best response is to ignore it, or to report a message to a forum moderator. Moderators usually delete troll messages or block trolls.  Negative emotions stirred up by trolls leak over into other discussions. Normally affable people can become bitter after reading an angry interchange between a troll and his victims, and this can poison previously friendly interactions between long-time users.

Finally, trolls create a paranoid environment, such that a casual criticism by a new arrival can elicit a ferocious and inappropriate backlash.

When trolls are ignored they step up their attacks, desperately seeking the attention they crave. Their messages become more and more foul, and they post ever more of them.

Alternatively, they may protest that their right to free speech is being curtailed. 

Perhaps the most difficult challenge for a webmaster is deciding whether to take steps against a troll that a few people find entertaining. Some trolls do have a creative spark and have chosen to squander it on being disruptive. There is a certain perverse pleasure in watching some of them. Ultimately, though, the webmaster has to decide if the troll actually cares about putting on a good show for the regular participants, or is simply playing to an audience of one -- himself.

Next time you are on a message board and you see a post by somebody whom you think is a troll, and you feel you must reply, simply write a follow-up message entitled "Troll Alert" and type only this:

The only way to deal with trolls is to limit your reaction and not to respond to trolling messages.  It is well known that most people don't read messages that nobody responds to, while 99% of forum visitors first read the longest and the largest threads with the most answers.
 

FYI: trolling is NOT encouraging the community, in the long run it is irritating to the community members, the moderators, and only helps in encouraging people to not read interesting threads anymore. Nothing good can come out of a troll.

If the moderators don't have a good discussion with the man that talks about himself in the 3rd person, I encourage people to stop posting on this and any other of his threads - don't feed the troll, don't encourage him. Note that all the good discussions of this thread were done while he wasn't trolling, between distant posts of him, and when he posts, we only rechew the same data over and over.

All that had to be said on the topic has been said and proven, yet the guy can't see the light. An empty bottleneck is not a problem (there is more then ennough time to process all keypress in emulation software between every emulated cycle), but an annoying troll is.

I suggest to everyone to use the ignore button on his username, too.

[Malenko]

you have no grip on simple input programming and now you want me to flash my BIOS with your hack?
pass.