Please help with dead system
in [Chips]
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From: Trent on 20 Nov 2006 06:26 On 17 Nov 2006 23:54:02 GMT Arno Wagner <me(a)privacy.net> wrote in Message id: <4s70cqFubcoeU1(a)mid.individual.net>: >In comp.sys.ibm.pc.hardware.misc Trent <none(a)dev.nul.pissoff> wrote: >> On 16 Nov 2006 15:02:04 GMT Arno Wagner <me(a)privacy.net> wrote in Message >> id: <4s3crcFthuckU1(a)mid.individual.net>: > >>>That is wrong. The beep codes are produced by the keyboard >>>MCU and that will beep a "CPU not present" if it is not >>>contacted by the CPU after a certain time. > >> Proof please. The beep codes are generated from the 8254 timer chip, which >> must be programmed by the processor. If the processor is missing or cannot >> do code/data fetches from the BIOS ROM, there are *no* post codes. Period. > >Since your information is wrong, I don't feel I have to proof >anything. But please remain unenlightened, if you want. Suuuure... *giggle* >Otherwise have a look at the schematics again. Should be at least PC-AT, Yep. I still have my IBM PC AT technical reference manual. Pg. 16 of 22 of the schematics. Looks like that pesky old 8254 needs programming to me. All those beep codes referenced by different BIOS manufacturers require a processor that can run well enough to do code and data fetches from ROM. >since I think the original PC and XT actually could not do this AFAIK. I've been debugging to the component level on processor, memory, and I/O boards since the 8080 days on Intel Multibus based systems, and you were most likely still suckling at your dad's teat, you confused pinhead. Why don't you quit while you're behind?
From: Trent on 20 Nov 2006 06:26 On 18 Nov 2006 22:35:31 GMT Arno Wagner <me(a)privacy.net> wrote in Message id: <4s9g5jFus4g6U1(a)mid.individual.net>: >Ok, whether or not the original IBM AT could beek a "CPU missing" is >really besides the point. More important is what amodern PC mainboard >would do. In order to find out, I just hookes an EPOX EP8-KRA2+ >up to a PSU and speaker. This board also has a POST display, >which hung at "FF" as expected. In addition there were no beeps, >so I retract my earlier statement: A modern mainboard does >not necessarily beep when the CPU is missing. I expect an apology is forthcoming?
From: Trent on 20 Nov 2006 07:06 On Sat, 18 Nov 2006 19:00:43 -0500 Tony Hill <hilla_nospam_20(a)yahoo.com> wrote in Message id: <0b5vl2ddh90fa7ba8gtd6kcp280e7gsksh(a)4ax.com>: >On Fri, 17 Nov 2006 05:20:07 -0500, Trent <none(a)dev.nul.pissoff> >wrote: > >>On 16 Nov 2006 15:02:04 GMT Arno Wagner <me(a)privacy.net> wrote in Message >>id: <4s3crcFthuckU1(a)mid.individual.net>: >> >>>That is wrong. The beep codes are produced by the keyboard >>>MCU and that will beep a "CPU not present" if it is not >>>contacted by the CPU after a certain time. >> >>Proof please. The beep codes are generated from the 8254 timer chip, which >>must be programmed by the processor. If the processor is missing or cannot >>do code/data fetches from the BIOS ROM, there are *no* post codes. Period. > >That is definitely false. I have pretty extensive experience on HP's >Business Desktop line, and every one of them will give you a beep code >(3 beeps) if there is no processor installed in the system. See page >A-13 from the following document: > >http://h20000.www2.hp.com/bizsupport/TechSupport/CoreRedirect.jsp?redirectReason=DocIndexPDF&prodSeriesId=472276&targetPage=http%3A%2F%2Fh20000.www2.hp.com%2Fbc%2Fdocs%2Fsupport%2FSupportManual%2Fc00368814%2Fc00368814.pdf I'd be curious to see a schematic of this motherboard, most likely it's a simple watch dog timer which is triggered after a certain period of bus inactivity. These are not the beep codes as referenced by the BIOS manufacturers. In any case, the OP in this thread's system is not an HP desktop it is a homebuilt, and will not output POST beep codes if no CPU is present. >Dell has a similar code for their new Dimensions, where only light 3 >of their diagnostics lights is on: > >http://support.dell.com/support/edocs/systems/dimC521/en/SM_EN/tshoot.htm#wp1064555 Irrelevant to the discussion, as there are no "beep codes" for a missing CPU chip. Additionally, that LED code is probably generated by default at power up. You could pry the chipset off the board with a big old screwdriver, AND have a fully functioning CPU and get the same result. >Note that these codes are NOT generated by any "8254 timer chip" as >such chips haven't existed on motherboards for 10+ years now. The >functionality of the 8254 timer chip has been incorporated into the >motherboard chipset, typically in the I/O controller or southbridge. [rolls eyes] In other words, it is generated from an 8254. Whether or not it's buried deep within the chipset matters not. There is still a device which behaves and acts exactly like an 8254 - three programmable timers with numerous modes of operation, and each MUST be programmed by the CPU before it will do anything at all. >This is also where the "Keyboard MCU" resides and it's also where the >POST beeps (or blinking lights, or voice warnings on some new systems) >come from. I've yet to see a design where the keyboard controller can write data to the speaker. >This is not some XT or AT system we're talking about here, things have >changed quite a bit in the past 25 years. Yet still there is a 100% software compatible 8254 device deep within. I never stated there was a discrete 24 pin DIP device for the function. From the 82801DB technical reference .pdf dated May 2003: "The ICH4 contains three counters which have fixed uses. All registers and functions associated with the 8254 timers are in the core well. The 8254 unit is clocked by a 14.31818 MHz clock." >---------------------------- >Tony Hill >hilla <underscore> 20 <at> yahoo <dot> ca You sig delimiter is improperly constructed.
From: Arno Wagner on 20 Nov 2006 10:11 In comp.sys.ibm.pc.hardware.misc Trent <none(a)dev.nul.pissoff> wrote: > On 18 Nov 2006 22:35:31 GMT Arno Wagner <me(a)privacy.net> wrote in Message > id: <4s9g5jFus4g6U1(a)mid.individual.net>: >>Ok, whether or not the original IBM AT could beek a "CPU missing" is >>really besides the point. More important is what amodern PC mainboard >>would do. In order to find out, I just hookes an EPOX EP8-KRA2+ >>up to a PSU and speaker. This board also has a POST display, >>which hung at "FF" as expected. In addition there were no beeps, >>so I retract my earlier statement: A modern mainboard does >>not necessarily beep when the CPU is missing. > I expect an apology is forthcoming? And why would you do that?
From: Franc Zabkar on 20 Nov 2006 16:30
On Sat, 18 Nov 2006 19:00:43 -0500, Tony Hill <hilla_nospam_20(a)yahoo.com> put finger to keyboard and composed: >On Fri, 17 Nov 2006 05:20:07 -0500, Trent <none(a)dev.nul.pissoff> >wrote: > >>On 16 Nov 2006 15:02:04 GMT Arno Wagner <me(a)privacy.net> wrote in Message >>id: <4s3crcFthuckU1(a)mid.individual.net>: >> >>>That is wrong. The beep codes are produced by the keyboard >>>MCU and that will beep a "CPU not present" if it is not >>>contacted by the CPU after a certain time. >> >>Proof please. The beep codes are generated from the 8254 timer chip, which >>must be programmed by the processor. If the processor is missing or cannot >>do code/data fetches from the BIOS ROM, there are *no* post codes. Period. > >That is definitely false. I have pretty extensive experience on HP's >Business Desktop line, and every one of them will give you a beep code >(3 beeps) if there is no processor installed in the system. See page >A-13 from the following document: > >http://h20000.www2.hp.com/bizsupport/TechSupport/CoreRedirect.jsp?redirectReason=DocIndexPDF&prodSeriesId=472276&targetPage=http%3A%2F%2Fh20000.www2.hp.com%2Fbc%2Fdocs%2Fsupport%2FSupportManual%2Fc00368814%2Fc00368814.pdf I've been looking at some hardware monitoring chips (eg Winbond's W83697HF). Its datasheet states that it provides an "Automatic Power On voltage detection Beep". It does this via a dedicated BEEP pin, not via the system timer. I presume that this BEEP signal would be ORed (or XORed) with the timer output from the chipset. The W83697HF also has several watchdog timers which can trigger the beeper when temperatures, fan speeds, and voltages fall outside their allowable ranges, but these all require programming. As was initially suggested, I concede that the keyboard MCU *could* operate as a watch dog timer and beep the speaker. All you would need would be an additional gate, and one of the MCU's many spare I/O pins on ports 1 and 2. Whether any motherboard design does this remains to be shown. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |