Hi Jan, thank you for the reply and suggestion to verify the memory SIMM modules. I was able to successfully recover the BIOS using the “hot flash” method with an old Soyo 440BX motherboard and celeron 300A CPU. After I booted the soyo board up I removed the 32-pin BIOS ROM chip from it and installed the Winbond W29EE011-15 BIOS ROM from the MS-4144 into the socket. Then I ran the excellent UniFlash 1.40 utility from the floppy drive and successfully was able to re-flash the W29EE011-15 back to a previous AMI BIOS version AF54S. The uniflash utility indicated that it was a successful flash. I then powered off the soyo board, removed the W29EE011 from it and replaced it back in the MS-4144. Then I held my breath and powered the thing up, and amazingly it booted right up ! After running some tests and adjusting some of the settings in the BIOS, I then proceeded to flash it again back to the same WF54S BIOS version with PS/2 mouse support that I had been running previously.
Everything has been running great for about a week now with my AM5x86-133ADZ @ 160MHz and Memtest86+ runs flawless with two 32MB and one 16MB SIMMs installed.
I don’t know what caused the BootBlock BIOS ROM checksum error, but UniFlash 1.40 definitely saved my motherboard and saved me from having to buy a TL866 ROM programmer. I hope this information helps some other folks out there that run into this problem in the future. Thanks to all in this thread, and lets keep these MS-4144s running!