Currently I still can't reconcile this but it's not that important. You know if addressing scheme is the problem then MBR would be read correctly but first partition wouldn't be read correctly, while here we have the issue that first partition is read correctly everywhere, but there is an issue with XTIDE and MBR since it fails to detect magic where it's supposed to be? The error messages I get correspond to FirstHardDiskSectorNotBootable and not FailedToLoadFirstSector which is a code path that tests for magic and fails if isn't there, code past the MBR adressing?
Still going through my to-do-list.
At [
here], in the '
I upgraded the release of 2.0.0 Beta 3+ of the ...' entry, I included an observation that the symptom appeared to be a booting one only. But in doing file CRC tests, I would not have tested many files. Still, odd.
I decided to try many more files.
I brought out an IBM XT, and to it, fitted an XT-IDE card, one that had XUB of release R625. The XT-IDE's CF card is 64 MB sized, but because I run IBM DOS 3.3, the DOS partition on it is 32 MB sized, enough for what I do. I put 20 MB worth of small files (440 files) onto that CF, scattered over about 100 directories. Using a particular
CRC tool, a record was made of the CRC of every single file. The record is a CRCKLIST.CRC file that resides in each directory. As expected, sweeping (SWEEP.EXE) through all directories showed that all files had a CRC that matched the recorded one.
Then, on the XT-IDE card, I removed the EEPROM containing XUB release R625, and in its place, put in an EEPROM containing XUB release R602. R602 on this new EEPROM was preconfigured for my XT-IDE card. Because of the aforementioned 'I upgraded the release of 2.0.0 Beta 3+ of the ...' entry, I knew that there would be a problem when I tried to boot from the XT-IDE card. Sure enough, I saw "
Missing operating system".
I then booted from an IBM DOS 3.3 boot floppy (i.e. no change in DOS version) then repeated a 'sweep' through all directories on the CF, using the CRC tool to see if all files had a CRC that matched the CRC recorded in CRCKLIST.CRC. They all matched !
Between R602 and R625, there was a change/fix in the CHS-to-CHS translation algorithm or CHS-to-LBA translation algorithm. With my
crude understanding of CHS translation, I can understand the "Missing operating system" at boot time. But what I don't understand is why a CRC validation of 20 MB worth of 440 files still gave no CRC mismatches.
Will someone adequately knowledgeable in the CHS translation subject, please explain that ?