Да, спасибо за совет, что-то получилось. Вот

D:\9>CBROM.EXE W545MS21.BIN /D
CBROM V2.07 (C)Award Software 2000 All Rights Reserved.

              ******** W545MS21.BIN BIOS component ********

 No. Item-Name         Original-Size   Compressed-Size Original-File-Name
================================================================================
  0. System BIOS       20000h(128.00K)139BCh(78.43K)original.tmp
  1. EPA pattern       00642h(1.56K)002A1h(0.66K)AWARDEPA.BIN
  2. XGROUP CODE       017A8h(5.91K)010D6h(4.21K)awardext.rom
  3. Other(0800:0000)  04000h(16.00K)025AAh(9.42K)n:\bios\award\opt_rom\ncr307.r
om
  4. Other(1000:0000)  02B99h(10.90K)02BD6h(10.96K)n:\bios\award\opt_rom\aha7850
.rom

  Total compress code space  = 1A000h(104.00K)
  Total compressed code size = 19EB3h(103.67K)
  Remain compress code space = 0014Dh(0.33K)

                          ** Micro Code Information **
Update ID  CPUID  |  Update ID  CPUID  |  Update ID  CPUID  |  Update ID  CPUID
------------------+--------------------+--------------------+-------------------

места действительно нет.
Делаем так:

D:\9>CBROM.EXE W545MS21.BIN /other 0800 Release
CBROM V2.07 (C)Award Software 2000 All Rights Reserved.
[Other] ROM is release
D:\9>CBROM.EXE W545MS21.BIN /other 1000 Release
CBROM V2.07 (C)Award Software 2000 All Rights Reserved.
[Other] ROM is release

получаем БИОС с кучей свободного места:

D:\9>CBROM.EXE W545MS21.BIN /D
CBROM V2.07 (C)Award Software 2000 All Rights Reserved.

              ******** W545MS21.BIN BIOS component ********

 No. Item-Name         Original-Size   Compressed-Size Original-File-Name
================================================================================
  0. System BIOS       20000h(128.00K)139BCh(78.43K)original.tmp
  1. EPA pattern       00642h(1.56K)002A1h(0.66K)AWARDEPA.BIN
  2. XGROUP CODE       017A8h(5.91K)010D6h(4.21K)awardext.rom

  Total compress code space  = 1A000h(104.00K)
  Total compressed code size = 14D33h(83.30K)
  Remain compress code space = 052CDh(20.70K)

                          ** Micro Code Information **
Update ID  CPUID  |  Update ID  CPUID  |  Update ID  CPUID  |  Update ID  CPUID
------------------+--------------------+--------------------+-------------------

патчим %)