Next bug in next message.
As promised, here it is.
Using that previous batch file, which creates a blank disk with 16 heads per cylinder and 63 sectors per track, I hop into lvmgui and it is happy to create a partition. I choose to do "start of free space" and "primary partition". That creates final1.vhd in the attached. Later on I create a non-bootable compatible volume (final2.vhd) and later on I format it as FAT32 (final3.vhd).
The only change in the MBR between final1 and final3 is the partition type is changed from 06 (FAT16) to 0C (FAT32 using - ironically - LBA). The start/end partition values remain unchanged.
So here is final3.vhd:
C:\vbox>hexdump final3.vhd 0x1b0 80
0001B0 00000000 00000000 00000000 33CC8001 ............3...
0001C0 01000C0F FFB23F00 00009190 0E000000 ......?.........
0001D0 00000000 00000000 00000000 00000000 ................
0001E0 00000000 00000000 00000000 00000000 ................
0001F0 00000000 00000000 00000000 000055AA ..............U.
Now we can see the x'0c' (FAT32) at 0x1C2 followed by the partition end head number (15 - ie maximum), the FF is sector 63 (x'3f') plus the 2 high bits set for the cylinder number (so B2 becomes 3B2).
So that means that cylinder 3B2 is completely maxed out - as is reasonable - giving cylinder alignment (although note that the starting LBA (after the x'b2') is 3F, so zero based means 40 sectors, ie it starts on head/track 1, sector 1. ie ArcaOS only needs track alignment, not cylinder alignment.
But regardless, the end of the partition is cylinder-aligned, meaning counting from the beginning of the disk (cylinder 0) to the end of the full cylinder 3B2 (946), we have a total of 947 cylinders with various stuff on it (starting with the MBR) or at least, assigned. 947 * 16 * 63 = 954576 sectors "in use". LBA is 0-based counting, so that means 0 to 954575 is "in use". With LBA 954575 being the end sector (inclusive).
That is hex e90cf
But ArcaOS has put an end LBA of e9091
That means if another system tries to use this disk to create the next partition, and uses LBA, as is normal, it will start at x'e9092', potentially trashing data in the first partition.
What is it out by?
cf-91 = decimal 62
So there's the ArcaOS bug - unless I have misdiagnosed.
And that's all the bugs I know of at the moment.