I struggled a lot on programming that darn chip. ASUS aflash 2.21 reports UNKNOWN, uniflash reports UNKNOWN, Awdflash 8.99 dowsn't work, Awdflash for ASUS doesn't work, and flashrom yells "Opening DMI pipe failed!"
I believe every programmable ROM should be programmable. So I pried it off and inserted it on a 3COM 905B card which worked with flashrom many times before. Now flashrom can detect it as Intel 28F001BN/BX-T but failed to erase or write. According to the datasheet, this is a 12V chip and it requires 12V at both PIN 1 and 30 to program. Currently I can't find another 1Mbit 12V board with known working flash utility so I decided to wire 12V to PIN 1 and 30 directly while the other 30 pins are still seated in the socket of 905B. Flashrom worked this time. By the way, 905B offers 5V at PIN 1 and NC at PIN 30.
Later when browsing ASUS website I saw a "pflash" tool with description "Flash for P2B Series Motherboard Solve for P2B series motherboard having unknown Flash ROM detected." I gave it a try and it works on my TX97-X with the Intel chip. Note that the update date of pflash is 5 years older than aflash 2.21, and it's a shame that the newer utility took off (or neglected) the support for at least that particular chip/board combination.