Hi!
For those who might be interessted: I have done
a "flash extender", that allows you to put
up to 4 MByte of FlashROM (8x512KB) into a standard
256KByte FlashROM socket. The basic trick is to
use bank switching. One major problem was to
get full read and write access to the address
range from 0xfffc0000 to 0xffffffff.
Thanks to Ron Minnich for pointing me to the
solution of the first problem. But to get write
access, i had to reverse engineer parts of the
Bios of my Asus A7V Motherboard.
The flash extender consists of only a few 1/10 inch DIL
parts: 2x74ALS32, 1x74ALS00, 1x74ALS138, 1x74ALS374,
1-8xAM29F040 and the firmware flash chip.
A switch allows you to select between the original
256KB Bios and the (512KB to 4MB) flash array
(BTW: using SMD parts, the flash extender could easily
extended to 32 MByte).
On the software front, i have done a flash programmer
that allows you to programm the flash array in circuit.
BTW: This flasher tool could easily downsized to
re-programm the factory default 256KB bios flash.
If you are interessted in hw&sw, please send
me a mail. This will increase the preasure on
me to do a downloadable wiring diagram and
a pcb-loayout.
Now to somesthing more Linuxbios related:
As the flash extender provides enough space for
a linux kernel and even a small root file system,
i can try to bring up Linuxbios on the Asus A7V.
But not to waste any time: does anybody else
yet bothered with an A7V on chipset level?
The problem is, that there are no specs
for the VIA-northbridge (BTW.: the southbridge
specs can be downloaded without signing an NDA here:
http://www.via.com.tw/pdf/productinfo/686a.pdf - i
told VIA about that, but they don�t seem to care
about it).
Do you think it is sufficient to read the
registers 0x40-0xff of the host-bridge and
the agp-bridge during factory default
operation and then write them when
booting linuxbios?
Comments are welcomed
Bernhard
--
Bernhard Kuhn | [EMAIL PROTECTED]
Linux Magazin | phone +49 (0) 89 993411-22
Stefan-George-Ring 24 | fax +49 (0) 89 993411-99
D-81929 Muenchen | http://www.linux-magazin.de
