------------------------------------------------------------------------------------------- Notes from looking at SBIOS.ASM from the DISK2 folder: BIOS E400 (USER area at EA80) BDOS D000 CLI C000 Cold boot enters the BIOS at E400. The BIOS then loads DOS (BDOS) from disk as follows: Track 2, sectors 1-30, followed by track 2, sectors 33-42. Note that sectors 31 and 32 are skipped (used by the NCR ROM). The BIOS performs common initialization for both cold boot and warm boot before jumping into the command line interpreter (CLI). This initialization includes calling the "Load CLI" function to load the CLI into RAM from a regular file on disk called "SYSTEM.CLI". At this point, all of SB80 is loaded. The "default" disk layout is SSDD with 256 byte sectors. Physical sector (256 byte) interleave is done in software as follows: 1,10,19,2,11,20,3,12,21 4,13,22,5,14,23,6,15,24 7,16,25,8,17,26,9,18 ------------------------------------------------------------------------------------------- Notes from looking at NCRGEN in the DISK4 folder: SYSGEN (NCRGEN) module layout in RAM: 1000h Boot loader 1100h CLI 2100h DOS 3500h BIOS The NCRGEN program combined with the full OS module as listed above appears to be the files OS.COM (ver 1.7) and OS1.COM (ver 1.8) in the DISK2 folder. READBOOT shows us that cold boot loader (loads the BIOS and jumps to it) is on track 1, sectors 1 and 2. Note that program comments do not agree with the code. READBIOS shows us that the BIOS is on track 1, sectors 3-52. Note that program comments do not agree with the code. READDOS to load the DOS from disk into RAM agrees with SBIOS code shown above (Track 2, sectors 1-30, 33-42). Note that program comments do not agree with the code. ------------------------------------------------------------------------------------------- Notes from looking at NBOOT in the DISK4 folder: The boot ROM appears to read all of track 1 into memory starting at address 100h. The track is expected to be double density with 256 byte sectors. The track is NOT de-interleaved as it is read into memory. The BOOT code mentioned in READBOOT above (NCRGEN) de-interleaves the track from memory as it moves it to the actual run-time location (E400h).