[comp.sys.ibm.pc] BIOS patch allowing AT speedup

hundt@wind.bellcore.com (tom hundt) (07/20/87)

Does anyone have the patch for IBM's AT BIOS that allows speeding the machine
up (via xtal replacement)?  I believe there's a loop in the disk(?) or POST
that needs its claws pulled.

 /=^=\  Thomas M. Hundt / BELLCORE Morristown NJ / hundt@bellcore.bellcore.com
 |   |  {seismo|ihnp4|ucbvzx|decvax|ulysses|allegra|clyde|princeton}...
/--_--\                                                      ...!bellcore!hundt

Dion_L_Johnson@cup.portal.com (07/28/87)

Note that the early PC-AT bios does NOT require a patch to
install a faster crystal.  My original AT (1984 model) worked
fine at 8MHz. The ROM chips had these hieroglyphics on top:
  T6181028 8414AAA
   TMM23256P-5878
   (c) IBM CORP 1981,-1984
and
  T6181029...
 ...-5879
I believe the change came along in the second year, along with the
30Mb drive, no?

In fact, you can have my original motherboard, complete with
those chips VERY CHEAP.  It is totally, massively dead due to
flying-sparks type transition into new, uninteresting state.