We doN't have such scrapyards here in Germany either so I just started to create my own. Randomly bought a 500 broken computers for me to sit between and procrastinate over fixing.
I've got quasi the same but in other unrelated PCB's. It's been an absolute goldmine of random parts after going over every PCB four or five times. I remember exactly what I do or don't have **somewhere** in the pile.
@@tony359 his perseverance paid off by providing one heck of a troubleshooting process example though! That's commendable for anyone who dares take such videos on. 😊
While the normal BIOS settings are stored in the RTC's SRAM (like in the original IBM AT), I believe the ESCD and DMI data are stored in the BIOS EEPROM. With the board's random crashes it's quite possible that it crashed once while writing them, so the data got corrupted. As you showed, the downloaded BIOS image had large empty blocks where your chip had data, so flashing the chip did empty those blocks. Since the ESCD contains all the Plug&Play settings, it's quite possible that due to the corruption some devices were configured in a way that causes conflicts with system board resources. You can see the BIOS updating the data right before the OS boot (e.g. 14:07). By the way, this is also a common failure with older boards that got a lot of use over their life, where this data has been written to the chip so many times, that this portion of the chip wears out. Of course there's no wear-leveling. So sometimes all you need is a new BIOS chip.
I almost spilled my drink when I saw that Frankenstein cooler on that Pentium II! I think I owe you an apology for sending you that horrible board! But you asked for something broken :) I just didn't know it is that bad! That flickering clock signal was probably due to the cracked inductor - that is good to know and keep in mind! I have to put that in my knowledgebase :) Great troubleshooting and repair of this board! I don't know if I would have found that cracked component. And the BIOS was just an additional arrow in the knee!
That BIOS thing was very unexpected. I don't think I've EVER fixed a board by flashing the BIOS again! Though that was a BETA Bios, maybe that was it! :) Ahah sorry for the Frankenstein! And thanks for the board!
This channel is quickly becoming one of my favorites for this kind of stuff great video as always and as far as that heatsink is concerned if it's stupid and works is it actually stupid
I've got the S version of this board. With a built in Adaptec SCSI controller. I've had it from new and it's still working. Used to have the DS version as well, with dual slot 1 and SCSI. Alas, that went walkies during a house move. Always look forward to your videos Tony. Thanks for all the effort you put in.
Το καλύτερο κομμάτι αυτού του βίντεο είναι ότι η επισκευή είχε πάρα πολλά διαφορετικά εξαρτήματα που είχαν πρόβλημα και χρειάστηκε να χρησιμοποιήσεις πολλές διαφορετικές μεθόδους διάγνωσης! Το θέμα με το BIOS είναι κάτι που δεν μου προξενεί προσωπικά τόσο μεγάλη εντύπωση, όμως πρώτη φορά βλέπω "χαλασμένο" BIOS να δείχνει εικόνα που να θυμίζει χαλασμένη κάρτα γραφικών... Εξαιρετική δουλειά ως συνήθως, χαιρετίσματα απ' την Ελλάδα! Δημήτρης.
Yes, first time for me too about the BIOS - "reflashing the BIOS" is standard process but maybe when the board is dead, not when it beeps! Thank you for watching!
Thank you your post! You are lucky not having a broken via istuation. That is the absolute nightmare. Second is the "partially" broken componenet which can not be seen under the microscope. Thank you to contribute to the knowledge database of symptoms - solutions of broken MBs. ESCD as a possible source of the problem is a nice addition to this knowledge base as well I was not aware of. This cooling-heating procedure is very good to point to the possible cracked component. We should pay much more attention to the inductors around the components.
Great video of trouble shooting a motherboard. In my experience when you switch a video card AGP to PCI 41:25 area, you have to cold reboot a few times ( on the same card) because internally it makes the switching on the first plug in, but has to be restarted.
Interesting. I see that it depends on the board. My intel refused to start on PCI at all. This Asus - once the BIOS was fixed - started with PCI with no delays. It just didn't make it into the video, it was already long enough! But it's great tip, I'll bear that in mind for future boards! Thanks!
Very nice repair, as ever. Now living not far away from the “zoppa” area you’ve mentioned I’ve understood and appreciated your determination and grande pazienza, davvero bravo
I appreciate your "advanced cooling solution" for the Slot 1 😜. Always a good idea to try things you presume wouldn't normally be the problem just to rule it out. Power cycling probably flipped some BIOS bits!
44:00 - I think BIOS just needed to be reseated. I noticed from the beginning that it probably took some impact in the past, it did not sit straight in the socket.
36:00 In fact issues with insufficient AGP power are not uncommon among LX boards. Look up the Riva TNT rework for the P2L97 rev 1.05. It does what you would expect, cut off the output pin of regulator Q6 and supply 3.3 V from the ATX power connector instead. The onboard linear reg is only good for about 2.5 A or something.
Awesome. i think that would have been a "weeeeee" board if it was on my workbench.... Keep up the good work! (Weeeeeee is when you chuck it and it goes weeeee)
É il mio primo video che vedo sul tuo canale e solo dopo 45 min di video scopro che sei italiano 😂 bravissimo comunque! Per la pazienza per aver riparato una scheda così “vintage” ;)
Such an error with the BIOS hit me too. I was prepairing two ASUS P5A-B for selling. The first one worked like a charme. The second board posted, booted into DOS and then crashed and had the same beeping like yours. Also tried replacing CPU, RAM, Vidcard. No luck. Than pulled the BIOC IC from the working board and it worked. Reflashed the bad BIOS chip, Board booted, but every Reboot corrupted it again. The good Chip was a Winbond, the other one was made by ATMel. So i grabbed two replacement chips. Another Winbond and an ATMel. The new Atmel showed the same error, the Winbond was fine. So both P5A-B were sold with stable Winbond chips.
the repeated loss of voltage and clock while the board was trying to read and execute bios code corrupted your bios eprom and no the cmos settings are not stored in that chip they are stored in a small ram located in the super io chip in your case or the dallas/odin rtc module on older boards
ESCD configuration data is stored in the BIOS flash and has for many many years, it is a main reason when dumping a BIOS and doing a compare like Tony did here against the BIOS downloaded from the manufacturers website that they don't match. At 11:51 in the video you can see the message "Update ESCD Successfully" that gets written directly to BIOS flash, see the Wikipedia article about Extended System Configuration Data for more details.
Thanks - I remembered that, but wondering whether with modern BIOS chips, which can be easily programmed, that was not the case anymore. @perhansson6718 seems to suggest that when the board says Update ESCD successfully it means the parameters were successfully stored on the BIOS?
@@perhansson6718 oh yeah thats right it did say update escd i didnt think it would have that being that its pentium 2 but yes escd gets written to the chip but not cmos settings which i was referring to
Once again many thanks for reminding me of the Uni Posca! I actually have some Uni Kuru Toga pencils. Did you ever end up getting that CPU storage tray sorted for your slot 1 and 2 cards?
@@tony359 It is conductive enough to halt a quartz oscillator. Typically a resistance around 1 MOhm or less across the quartz crystal prevents it from starting. Isopropyl alcohol can do this as well.
You are not wrong but I can assure you it wouldn't stop the clock every time. I edited it off a bit but at some point no matter how much cold spray I would use, it would not stop again. The issue was 100% the inductor. Then we agree that having water on a crystal is not great - but won't necessarily stop it.
There's a thing called ESCD which is a system configuration data BIOS flashes into a separate flash page each time hw configuration changes. Add/remove ram, install or remove some PCI or ISA card - BIOS will write an update to ESCD. It is possible to get this data corrupted in a way that it crashes the system during early initialisation stages and to get weird things happening as a result - like ones you were having with videocard failing to be detected/initialized properly and later on getting stuck with code 41. It might so happen that you got ESCD area corrupted due to clock generation malfunction right at the moment flash chip was updating ESCD page. By reflashing your BIOS you got ESCD area into a clean "factory" state and it got the deal done fixing the mobo.
@tony359 Nope, ESCD is typically stored in the same chip with BIOS image, just in the separate flash page(s). CMOS, on the other hand, is typically stored in the battery-backed NVRAM (which is usually SRAM-based). "Clearing CMOS" is done by simply disconnecting this NVRAM from the battery and letting data decay leading to a checksum error on the next boot and re-initialisation of the CMOS contents. To get ESCD reset you need to do a reflash, there's no way around it. BTW this ESCD thingy sometimes can lead to a strange kind-a faults with a board failing to boot due to being unable to complete "Updating ESCD data..." step. Two typical reasons for such problems are either worn-out flash chip that can no longer properly erase/flash page used for ESCD storage or trying to use an incompatible flash chip that this particular mobo/chipset are unable to flash (for example some flash chips require 12V to be sent to PGM pin to enable flashing but there are quite a lot of more modern mobos that send 5V to this pin instead - flashing won't work for these combinations).
At that time BIOS settings were not saved in the FLASH chip. If there were differences, it was bit rot. It just seems that it manifested itself with a little bit of delay. IMO, it was much better solution than what we have today. Settings were saved in RTC chip. It had some spare SRAM inside for that purpose. Simply removing the battery would restore all settings to their default values. BIOS ROM was immutable, except for an update. Even that could be disabled by disconnecting nWE pin and pulling it high. BTW. BIOS ROM itself has a checksum. If it fails some boards refuse to boot and some display an error message and try to boot anyway.
ESCD configuration data is stored in the BIOS flash and has for many many years, it is a main reason when dumping a BIOS and doing a compare like Tony did here against the BIOS downloaded from the manufacturers website that they don't match. At 11:51 in the video you can see the message "Update ESCD Successfully" that gets written directly to BIOS flash, see the Wikipedia article about Extended System Configuration Data for more details.
Thanks all for your comments, I see there are two paths: on the BIOS or on the RTC. I was aware of the RTC RAM for the BIOS settings - I'd imagine that was necessary when the BIOS were not easily rewritable. So on this model it's being stored on the BIOS chip itself?
@@tony359 BIOS settings are stored in RTC RAM (usually 128 bytes in size that is held by the CR2032 coin cell) ESCD data is stored in flash memory (the BIOS chip itself) would be interesting if you kept a copy of the non-working BIOS dump to compare it with a working one, another easy way to test is dump the BIOS: then make some hardware change that requires updating the ESCD data like adding some more PCI cards, then dump the BIOS again and compare...
@ I did not know about ESCD thing. I've seen this message many times but never payed any closer attention to it. Well, I guess it better late than never to learn something new.
I wonder what was behind ASUS decision to make 3.3V power supply on mobo directly rather than utilizing ATX 3.3V power line. Maybe there was some sort of AT to ATX adapters? Later boards, e.g. TUSL2-C, seems to have this weird feature too. I was once confused by it while checking my PCB design of CNR card. There was no continuity from ATX to 3.3v pins on CNR slot, but when board is powered up 3.3 volts was there.
I'd imagine that that way you rule out any possible issues with 3.3V due to weak PSUs. Though I understand that revisions before 2.05 had weak 3.3V on the board...
Oh? You're in the UK? And B&B is in Dubai? And there I am, recently moved from the UK to Germany!!! Also, I know what you said! I lived with an Italian guy in my uni days, so I know a few words of Italian :P EDIT Ngl, this reminded me of the BBC micro prototype which would crash unless someone kept their finger on a specific point of the board, during a demo to BBC executives. xD
As always, nice videos. tks a lot! So, when you come to São Paulo, Brasil, please, let me know an feel invited to drink a nice cofee at morning and, maybe, some capirinha and mojito at afternoon.
Good work. But these P2L97 are trash. Unstable/ relatively slow and you should never try to update the BIOS without a real eeprom writer. The worst Mainboard i ever had. And i had many.
The AGP port is the cause of most boot failures when testing without a case. The graphics card needs to be as close to vertical. It also happens with some PCI cards too.
Oh yes, testing on an open bench is always asking for trouble but it generally works. But always expecting a crash or two with cards flapping in the wind of course!
ESCD configuration data is stored in the BIOS flash and has for many many years, it is a main reason when dumping a BIOS and doing a compare like Tony did here against the BIOS downloaded from the manufacturers website that they don't match. At 11:51 in the video you can see the message "Update ESCD Successfully" that gets written directly to BIOS flash, see the Wikipedia article about Extended System Configuration Data for more details.
@@perhansson6718 Uhm the CMOS Clear should trigger checksum error which should cause ESCD to be ignored and rebuilt from scratch, barring possible firmware bugs.
@@SianaGearz When the clock was unstable the routine that writes the ESCD data could easily write it to any location of the flash memory thus corrupting it and preventing the system from booting...
You know the problem is bad when Tony starts to curse in Italian!!
ahahah it's inevitable! :D
@@tony359 Didn't know till now you could speak Italian Tony!
We doN't have such scrapyards here in Germany either so I just started to create my own. Randomly bought a 500 broken computers for me to sit between and procrastinate over fixing.
that's the spirit! :)
I've got quasi the same but in other unrelated PCB's. It's been an absolute goldmine of random parts after going over every PCB four or five times. I remember exactly what I do or don't have **somewhere** in the pile.
Excellent.
Intermittent issues is one of the most difficult things to troubleshoot. Great job on this Tony!
... and the most challenging to make a video about! The latest video from Adrian (2h55m) is a testament for that! Thanks!
@@tony359 his perseverance paid off by providing one heck of a troubleshooting process example though! That's commendable for anyone who dares take such videos on. 😊
Thank you!
I bought an Asus P2B board from Alex (My daughter lives in Dubai). The repair work he did was absolutely brilliant. He is a very nice guy.
He is and I did watch the P2B "repairathon" when he published it! :)
Hat off for figuring out that inductor was bad
Thanks!
While the normal BIOS settings are stored in the RTC's SRAM (like in the original IBM AT), I believe the ESCD and DMI data are stored in the BIOS EEPROM. With the board's random crashes it's quite possible that it crashed once while writing them, so the data got corrupted. As you showed, the downloaded BIOS image had large empty blocks where your chip had data, so flashing the chip did empty those blocks.
Since the ESCD contains all the Plug&Play settings, it's quite possible that due to the corruption some devices were configured in a way that causes conflicts with system board resources.
You can see the BIOS updating the data right before the OS boot (e.g. 14:07).
By the way, this is also a common failure with older boards that got a lot of use over their life, where this data has been written to the chip so many times, that this portion of the chip wears out. Of course there's no wear-leveling. So sometimes all you need is a new BIOS chip.
quite likely! And because of that, it failed to properly initialise the video cards!
I almost spilled my drink when I saw that Frankenstein cooler on that Pentium II! I think I owe you an apology for sending you that horrible board! But you asked for something broken :) I just didn't know it is that bad! That flickering clock signal was probably due to the cracked inductor - that is good to know and keep in mind! I have to put that in my knowledgebase :)
Great troubleshooting and repair of this board! I don't know if I would have found that cracked component. And the BIOS was just an additional arrow in the knee!
That BIOS thing was very unexpected. I don't think I've EVER fixed a board by flashing the BIOS again! Though that was a BETA Bios, maybe that was it! :)
Ahah sorry for the Frankenstein! And thanks for the board!
BuB você realmente testou a capacidade do Tony, mas deu tudo certo! Parabéns ao canal de vocês! Abraços do Brasil.
Yes, he tested me. And I won! :D
@@tony359 could the 3.3V jumping around the place constantly caused the BIOS to corrupt itself?
for sure!
Very nice video :) That BIOS issue surprised me just as much. Thank you for sharing.
Thank you Sir - I recorded that segment reluctantly, I was quite sure I was wasting my time...
Never say never! :)
This channel is quickly becoming one of my favorites for this kind of stuff great video as always and as far as that heatsink is concerned if it's stupid and works is it actually stupid
ahah thanks! Well, it works until it falls on the Mobo and then I need another repair video! :)
Mine too!
38:10 CT4 and CT6 are tantalum capacitors, they do look like diodes, but they're capacitors
ah, it makes much more sense now, thanks!
The area in the bios is most likely the ESCD. The config itself is written to the RTC memory.
understood - I got it a bit wrong but still something that gets written by the BIOS routine. Clearly, it wasn't :)
Fantastic troubleshooting! I'm so glad you were able to eventually find and correct the fault! Intermittent issues are the worst to correct!
Yes, that was rewarding indeed! Thanks for watching!
Great troubleshoot! Amazing work, sir.
Thank you so much!
The face you made when the bios brought it back to life was priceless
eheh - it was so unexpected...
Good job sorting through the multiple issues, Tony!
Thank you!
I've got the S version of this board. With a built in Adaptec SCSI controller. I've had it from new and it's still working. Used to have the DS version as well, with dual slot 1 and SCSI. Alas, that went walkies during a house move. Always look forward to your videos Tony. Thanks for all the effort you put in.
I wasn't aware of those versions, it sounds pretty cool! Too bad they got lost! Thanks for watching!
What a long strange trip, both for the board and for your repair of it! Congrats on sticking with it and succeeding!
Thanks!
Το καλύτερο κομμάτι αυτού του βίντεο είναι ότι η επισκευή είχε πάρα πολλά διαφορετικά εξαρτήματα που είχαν πρόβλημα και χρειάστηκε να χρησιμοποιήσεις πολλές διαφορετικές μεθόδους διάγνωσης! Το θέμα με το BIOS είναι κάτι που δεν μου προξενεί προσωπικά τόσο μεγάλη εντύπωση, όμως πρώτη φορά βλέπω "χαλασμένο" BIOS να δείχνει εικόνα που να θυμίζει χαλασμένη κάρτα γραφικών...
Εξαιρετική δουλειά ως συνήθως, χαιρετίσματα απ' την Ελλάδα! Δημήτρης.
Yes, first time for me too about the BIOS - "reflashing the BIOS" is standard process but maybe when the board is dead, not when it beeps!
Thank you for watching!
That was completely weird! Great work, especially the detective work, and all your labor.
Thank you Sir!
Thank you your post! You are lucky not having a broken via istuation. That is the absolute nightmare. Second is the "partially" broken componenet which can not be seen under the microscope. Thank you to contribute to the knowledge database of symptoms - solutions of broken MBs. ESCD as a possible source of the problem is a nice addition to this knowledge base as well I was not aware of. This cooling-heating procedure is very good to point to the possible cracked component. We should pay much more attention to the inductors around the components.
I should have looked into that clock IC sooner 🙂
44:23 The rough sea treatment 😂
ahahah yes!
Great video of trouble shooting a motherboard. In my experience when you switch a video card AGP to PCI 41:25 area, you have to cold reboot a few times ( on the same card) because internally it makes the switching on the first plug in, but has to be restarted.
Interesting. I see that it depends on the board. My intel refused to start on PCI at all. This Asus - once the BIOS was fixed - started with PCI with no delays. It just didn't make it into the video, it was already long enough!
But it's great tip, I'll bear that in mind for future boards! Thanks!
Very nice repair, as ever. Now living not far away from the “zoppa” area you’ve mentioned I’ve understood and appreciated your determination and grande pazienza, davvero bravo
ahahah I got that from a guy ages ago and it stuck with me! :D
Grazie!
I love the tricky ones, so much fun to watch. That was ace! Well done.
Thank you!
What a trip down the rabbit hole, nice job Tony.
Thanks Ted!
Nicely done!
I appreciate your "advanced cooling solution" for the Slot 1 😜. Always a good idea to try things you presume wouldn't normally be the problem just to rule it out. Power cycling probably flipped some BIOS bits!
44:00 - I think BIOS just needed to be reseated. I noticed from the beginning that it probably took some impact in the past, it did not sit straight in the socket.
Anything is possible but I did flash that BIOS earlier in the video and also sprayed some contact cleaner...
I watch all your videos, this was the most enjoyable video you made recently. Bravo 👏
oh thanks for your kind words!!
that was just awesome, Tony! super video and repair!
Thank you!
36:00 In fact issues with insufficient AGP power are not uncommon among LX boards. Look up the Riva TNT rework for the P2L97 rev 1.05. It does what you would expect, cut off the output pin of regulator Q6 and supply 3.3 V from the ATX power connector instead. The onboard linear reg is only good for about 2.5 A or something.
Yes I read that before 2.05 were not good at 3.3V. Weird, why would they go for that on-board regulation then!
Look that face when it suddenly posts and then the wwhat... epic! 👏 and of course, congratulations!
ahahah yes! Thanks!
Great video Tony. I have a board with similar issues (Biostar M7VIZ) with similar issues, and you gave me some ideas. Bravissimo !!!
Fantastic, good luck!
Amazing detective work! 🎉
Thank you!
Awesome. i think that would have been a "weeeeee" board if it was on my workbench.... Keep up the good work! (Weeeeeee is when you chuck it and it goes weeeee)
ahah I was wondering!
I was very close to "weeee" it :D
É il mio primo video che vedo sul tuo canale e solo dopo 45 min di video scopro che sei italiano 😂 bravissimo comunque! Per la pazienza per aver riparato una scheda così “vintage” ;)
Quando "esce il Toscano" come dice MVVBlog :D
Feci un video di presentazione qualche tempo fa: ua-cam.com/video/tB0wqZT2KWk/v-deo.html
E benvenuto! :)
Ciao! Such patience and perseverance. But in the end, you got it, another repair successful. I miss my Pentium II system, it was my first PC.
Thank you! Mine was a 386 DX 25 :)
Such an error with the BIOS hit me too. I was prepairing two ASUS P5A-B for selling. The first one worked like a charme. The second board posted, booted into DOS and then crashed and had the same beeping like yours. Also tried replacing CPU, RAM, Vidcard. No luck. Than pulled the BIOC IC from the working board and it worked. Reflashed the bad BIOS chip, Board booted, but every Reboot corrupted it again. The good Chip was a Winbond, the other one was made by ATMel. So i grabbed two replacement chips. Another Winbond and an ATMel. The new Atmel showed the same error, the Winbond was fine. So both P5A-B were sold with stable Winbond chips.
very interesting! thanks!
This was a great lesson, excellent info to know. Italian is such a beautiful language. Btw, I've got your 90 degree board on the way. Grazie
Prego, I hope you like it :)
User settings are saved in NVRAM in the chipset (RTC chip in older PCs), not in the EEPROM.
you're right, I was mistaken. But ESCD apparently are.
Hello "the Tony", great to see you again.
Hello there!
Great job, that was devilishly hard to find. I am gonne send you all my stuff that I cannot make sense of. :P
ahah OMG, sounds challenging! :)
Best order some more contact cleaner with the Slot1 heatsink. Great diagnostic tips in this video.
I need a bucket of contact cleaner indeed! :)
Great job, finding one little inductor its like a needle in haystack.
it is! Thank you!
OMG Tony so many faults! That board didn't need a repair... it needed an exorcism!
ahah yes!
Isso sim foi um grande desafio, mas conseguiu! Parabéns pelo excelente trabalho!
Muito Obrigado!
the repeated loss of voltage and clock while the board was trying to read and execute bios code corrupted your bios eprom and no the cmos settings are not stored in that chip they are stored in a small ram located in the super io chip in your case or the dallas/odin rtc module on older boards
ESCD configuration data is stored in the BIOS flash and has for many many years, it is a main reason when dumping a BIOS and doing a compare like Tony did here against the BIOS downloaded from the manufacturers website that they don't match. At 11:51 in the video you can see the message "Update ESCD Successfully" that gets written directly to BIOS flash, see the Wikipedia article about Extended System Configuration Data for more details.
Thanks - I remembered that, but wondering whether with modern BIOS chips, which can be easily programmed, that was not the case anymore. @perhansson6718 seems to suggest that when the board says Update ESCD successfully it means the parameters were successfully stored on the BIOS?
Also the Intel PIIX4 southbridge includes an RTC module along with its SRAM.
@@perhansson6718 oh yeah thats right it did say update escd i didnt think it would have that being that its pentium 2 but yes escd gets written to the chip but not cmos settings which i was referring to
@@tony359 if the board has escd thats likely what corrupted the chip because the board crashed as it was writing the escd stuff to the chip
Once again many thanks for reminding me of the Uni Posca! I actually have some Uni Kuru Toga pencils.
Did you ever end up getting that CPU storage tray sorted for your slot 1 and 2 cards?
Not yet, one day I'll think of something :)
I love that CPU cooling setup!!!! 😍
ahah! The Pentium-XboX (it's an XboX cooler!)
Applying cold air deposits water to the oscillator circuitry and of course stops it completely.
water is non conductive though!
@@tony359 It is conductive enough to halt a quartz oscillator. Typically a resistance around 1 MOhm or less across the quartz crystal prevents it from starting. Isopropyl alcohol can do this as well.
You are not wrong but I can assure you it wouldn't stop the clock every time. I edited it off a bit but at some point no matter how much cold spray I would use, it would not stop again. The issue was 100% the inductor. Then we agree that having water on a crystal is not great - but won't necessarily stop it.
"Mo non lo fa più, maremma zoppa" è uscito dal cuore 😂
eh, per forza! :)
Qui sarebbero partiti apprezzamenti al tegame smaniàto dell'eventuale mamma della scheda :'D
There's a thing called ESCD which is a system configuration data BIOS flashes into a separate flash page each time hw configuration changes. Add/remove ram, install or remove some PCI or ISA card - BIOS will write an update to ESCD. It is possible to get this data corrupted in a way that it crashes the system during early initialisation stages and to get weird things happening as a result - like ones you were having with videocard failing to be detected/initialized properly and later on getting stuck with code 41. It might so happen that you got ESCD area corrupted due to clock generation malfunction right at the moment flash chip was updating ESCD page. By reflashing your BIOS you got ESCD area into a clean "factory" state and it got the deal done fixing the mobo.
thank you! And that does not go away with "Clear CMOS"?
@@tony359 Nope, that only clears the contents of the RTC SRAM.
@tony359 Nope, ESCD is typically stored in the same chip with BIOS image, just in the separate flash page(s). CMOS, on the other hand, is typically stored in the battery-backed NVRAM (which is usually SRAM-based). "Clearing CMOS" is done by simply disconnecting this NVRAM from the battery and letting data decay leading to a checksum error on the next boot and re-initialisation of the CMOS contents. To get ESCD reset you need to do a reflash, there's no way around it. BTW this ESCD thingy sometimes can lead to a strange kind-a faults with a board failing to boot due to being unable to complete "Updating ESCD data..." step. Two typical reasons for such problems are either worn-out flash chip that can no longer properly erase/flash page used for ESCD storage or trying to use an incompatible flash chip that this particular mobo/chipset are unable to flash (for example some flash chips require 12V to be sent to PGM pin to enable flashing but there are quite a lot of more modern mobos that send 5V to this pin instead - flashing won't work for these combinations).
Very interesting video. Sherlock Tony to the rescue! :D
Of course, Watson!
Very interesting video!
Thanks for stopping by!
At that time BIOS settings were not saved in the FLASH chip. If there were differences, it was bit rot. It just seems that it manifested itself with a little bit of delay. IMO, it was much better solution than what we have today. Settings were saved in RTC chip. It had some spare SRAM inside for that purpose. Simply removing the battery would restore all settings to their default values. BIOS ROM was immutable, except for an update. Even that could be disabled by disconnecting nWE pin and pulling it high. BTW. BIOS ROM itself has a checksum. If it fails some boards refuse to boot and some display an error message and try to boot anyway.
ESCD configuration data is stored in the BIOS flash and has for many many years, it is a main reason when dumping a BIOS and doing a compare like Tony did here against the BIOS downloaded from the manufacturers website that they don't match. At 11:51 in the video you can see the message "Update ESCD Successfully" that gets written directly to BIOS flash, see the Wikipedia article about Extended System Configuration Data for more details.
Thanks all for your comments, I see there are two paths: on the BIOS or on the RTC. I was aware of the RTC RAM for the BIOS settings - I'd imagine that was necessary when the BIOS were not easily rewritable. So on this model it's being stored on the BIOS chip itself?
@@tony359 BIOS settings are stored in RTC RAM (usually 128 bytes in size that is held by the CR2032 coin cell) ESCD data is stored in flash memory (the BIOS chip itself) would be interesting if you kept a copy of the non-working BIOS dump to compare it with a working one, another easy way to test is dump the BIOS: then make some hardware change that requires updating the ESCD data like adding some more PCI cards, then dump the BIOS again and compare...
oh I see - I did not unfortunately. I was confident that what I was observing was nothing relevant! :)
@ I did not know about ESCD thing. I've seen this message many times but never payed any closer attention to it. Well, I guess it better late than never to learn something new.
the mchammer board: can't touch this!
ahahahaha!
"I was about to throw this board out of the window"
...
"I had great fun fixing this board"
Alright, Tony!
oh well, the moment you fix something all the hours spent in frustration disappear!
@tony359 hahah well that I do understand all too well ❤️🩹
that was such a journey
yes but good ending :)
The BIOS literally bit-rotted right in front of you... Unreal lol
Very much!
I wonder what was behind ASUS decision to make 3.3V power supply on mobo directly rather than utilizing ATX 3.3V power line. Maybe there was some sort of AT to ATX adapters?
Later boards, e.g. TUSL2-C, seems to have this weird feature too. I was once confused by it while checking my PCB design of CNR card. There was no continuity from ATX to 3.3v pins on CNR slot, but when board is powered up 3.3 volts was there.
I'd imagine that that way you rule out any possible issues with 3.3V due to weak PSUs. Though I understand that revisions before 2.05 had weak 3.3V on the board...
I think that You may brick the bios config during touch debugging crashes.
probably and I don't blame the poor bios :)
i got one.. two of these.. maybe a design issue.. for they.. don't work :// ++anymore++
ops!
Oh? You're in the UK? And B&B is in Dubai?
And there I am, recently moved from the UK to Germany!!!
Also, I know what you said! I lived with an Italian guy in my uni days, so I know a few words of Italian :P
EDIT
Ngl, this reminded me of the BBC micro prototype which would crash unless someone kept their finger on a specific point of the board, during a demo to BBC executives. xD
ahah I am familiar with those "prototype" demos - in different industries :)
As always, nice videos. tks a lot! So, when you come to São Paulo, Brasil, please, let me know an feel invited to drink a nice cofee at morning and, maybe, some capirinha and mojito at afternoon.
Ahah that would be amazing! Muito obrigado!
25:19 Your MoBo is DEAD 😅
It wasn't hard to FIX, it was hard to FIND - lol -.
You can imagine they just strip stuff and toss it through the air into a bin 5m away - lol -.
oh yes, that board has been tossed around like crazy!
Good work. But these P2L97 are trash. Unstable/ relatively slow and you should never try to update the BIOS without a real eeprom writer. The worst Mainboard i ever had. And i had many.
Yes, I am not impressed, it doesn't support much :)
The AGP port is the cause of most boot failures when testing without a case. The graphics card needs to be as close to vertical. It also happens with some PCI cards too.
Oh yes, testing on an open bench is always asking for trouble but it generally works. But always expecting a crash or two with cards flapping in the wind of course!
Because there are stored data about PnP configuration...
correct - but I didn't know! :)
Sell to someone who is an outdoor computing enthusiast and lives in Siberia. Problem solved.
😊
You should learn how a bios work, before making ridiculous comments.
ESCD configuration data is stored in the BIOS flash and has for many many years, it is a main reason when dumping a BIOS and doing a compare like Tony did here against the BIOS downloaded from the manufacturers website that they don't match. At 11:51 in the video you can see the message "Update ESCD Successfully" that gets written directly to BIOS flash, see the Wikipedia article about Extended System Configuration Data for more details.
@del4you2 - I'll make sure I study more for next video, thanks for your comment!
@perhansson6718 - Thanks.
@@perhansson6718 Uhm the CMOS Clear should trigger checksum error which should cause ESCD to be ignored and rebuilt from scratch, barring possible firmware bugs.
@@SianaGearz When the clock was unstable the routine that writes the ESCD data could easily write it to any location of the flash memory thus corrupting it and preventing the system from booting...