bios in flash, intermittent extensions boot 
Author Message
 bios in flash, intermittent extensions boot

Sorry folks if this is the wrong group,
perhaps you could point me to the right one?

We're using SBC that has BIOS and all extensions
(video, bootprom, etc) programmed in flash.

Symptoms:
1. bootprom executes intermittently, when it's not executed all we get is
prompt
DRIVE NOT READY
Insert BOOT diskette in A:
Press any key when ready

2. If put bootprom at D0000 it doesn't execute at all.

3. Sometimes different video BIOSes come up on power-up (same flash):
CHIPS 65548 VGA 32KB BIOS DD Flat Panel
or
95 Chips and Technologies inc.

Somebody told me that if flash is slow it may cause a failure to read a
byte correctly so the checksum algorithm will fail and the BIOS then
rejects it. If that's the case why BIOS itself executes correctly?

Anybody had such experience?

I'd me more than grateful to know your clues how to solve that.

Thanks,

Pavel



Sun, 29 Oct 2000 03:00:00 GMT  
 bios in flash, intermittent extensions boot

Quote:

> Sorry folks if this is the wrong group,
> perhaps you could point me to the right one?

 comp.arch.embedded, but here is OK as well.

Quote:
> We're using SBC that has BIOS and all extensions
> (video, bootprom, etc) programmed in flash.

> Symptoms:
> 1. bootprom executes intermittently, when it's not executed all we get is
. . .
> Somebody told me that if flash is slow it may cause a failure to read a
> byte correctly so the checksum algorithm will fail and the BIOS then
> rejects it. If that's the case why BIOS itself executes correctly?

It probably wouldn't, so that probably isn't the problem.

I have two different guesses:

1)  You main chipset supports mapping the UMB areas to your choice of
flash, shadow ram, or the ISA bus.  Your BIOS copies and maps things
into shadow ram.  On reset, the chip isn't properly cleared, so you
come up accessing shadow ram when you should be accessing flash.
Remove all power, short out any large caps, wait another minute for
good luck and then reapply power.  Is the startup more consistent
under those conditions than under a simple reset?

2) Your bootprom code validates whatever port it is planning to use
later.  Sometimes this happens too early in the power up, and that
device isn't ready yet and the bootprom module cacels itself.

--
http://www.erols.com/johnfine/
http://www.geocities.com/SiliconValley/Peaks/8600/



Mon, 30 Oct 2000 03:00:00 GMT  
 
 [ 2 post ] 

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