Solved change BIOS to support a bootloader

January 21, 2016 at 08:07:28
Specs: Windows 7, 2GB
Its probably possible to read back the BIOS chip using SPI, and then use a hardware tool to replace the image using the file header and write a copy to a new chip.
Although the advantage of this method is that in theory a 25L16/32 could be replaced with a 25L128 so the extra space can then be used to load a failsafe OS for those times some virus from Hell nails the system.

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#1
January 21, 2016 at 20:27:17
A bios already has the ability to boot from various devices by selecting their order. An ATA or SATA add-on card has its own bios to select a booting drive as did most old SCSI cards. The original IBM PC/XT had an option ROM that would boot BASIC if there were no drives or disks in the drives. I believe an option ROM to load DOS still exists There is PLOP boot manager that allows you to boot from devices not supported by the bios. It's done by loading their software to your hard drive so when booting from the hard drive their boot menu comes up.

I don't know if there are any windows versions of 'OS on a chip' but if so they wouldn't need to be jammed onto an existing bios chip as an option ROM or secondary bios could be built onto a PCI card.


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#2
January 22, 2016 at 22:20:45
Hi, yes in fact this HP does have a few other options such as HDD test.

I'd like it to be able to boot Damn Small Linux which if compressed is rumored to actually fit (barely) in 64MB.
These chips are actually 16MB units so in theory loading just the kernel is possible and simply read back the rest of the needed files from the non bootable SD slot.


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#3
January 23, 2016 at 16:24:46
✔ Best Answer
You may not be able to boot to a SD card but you can boot to a USB flash drive and they are no longer very expensive and they are available in rather large sizes now.

You have to be a little bit crazy to keep you from going insane.


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#4
January 23, 2016 at 20:18:32
Hi, thanks for that.
Does anyone here know if modifying a BIOS to add boot functionality to an SD reader is legal? (waitasec, why is it an issue on a machine that is only ever going to be used just for hacking micro-controller code etc)

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#5
January 24, 2016 at 20:14:38
About the only real problem with tinkering with the BIOS yourself is that if you mess up and it does not work at all then you may not get a second chance because updating your BIOS again (with original or another try) is not possible without a working BIOS.

You have to be a little bit crazy to keep you from going insane.


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#6
January 24, 2016 at 21:04:13
Way ahead here, have a few identical chips to clone onto.
First Pi Zero project too, SPI chip cloner :-)
Also the chip is socketed (£5) so less of an issue

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