I just wanted to report back for all of you who helped me and gave great
Thanks for the CHS/LBA info.
This is an IDE Flash module that goes directly into the MBs slot. It
doesn't allow to connect another device beside it, so it also doesn't
have a master/slave jumper.
It has a capacity of 512 MB. I tested it on another PC, from around
2000, which auto-detected it as C/H/S 993/16/63 (no boot-up as it was
still empty at that time, I just did the BIOS auto-detection).
On the 486 I've put that in for the IDE device as custom type 82. The
other values, LZ and WP, I left at 0. I assume for a flash drive they
are simply not important.
But it doesn't boot. It halts with the error message: "partition
signature != 55AA"
I've personally checked: all partitions and the MBR have that signature.
I managed to find an old external USB HDD which has an IDE interface
inside, and I connected the flash module to my regular PC.
> # dmesg | tail
> [23705.522176] scsi 7:0:0:0: Direct-Access TRANSCEN
D 0000 PQ: 0 ANSI: 0
> [23705.522746] sd 7:0:0:0: Attached scsi generic sg3 type 0
> [23705.523265] sd 7:0:0:0: [sdc] 1000944 512-byte logical blocks:
(512 MB/489 MiB)
> [23705.524141] sd 7:0:0:0: [sdc] Write Protect is off
> [23705.524145] sd 7:0:0:0: [sdc] Mode Sense: 27 00 00 00
> [23705.525012] sd 7:0:0:0: [sdc] No Caching mode page found
> [23705.525018] sd 7:0:0:0: [sdc] Assuming drive cache: write through
> [23705.528556] sdc: sdc1 sdc2 sdc3
> [23705.531653] sd 7:0:0:0: [sdc] Attached SCSI disk
> # parted /dev/sdc print
> Model: TRANSCEN D (scsi)
> Disk /dev/sdc: 512MB
> Sector size (logical/physical): 512B/512B
> Partition Table: msdos
> Disk Flags:
> Number Start End Size Type File system Flags
> 1 32,3kB 52,7MB 52,7MB primary
> 2 52,7MB 74,0MB 21,3MB primary
> 3 74,0MB 480MB 406MB primary fat16 boot
As you can see, the third primary partition is for FreeDOS. I've decided
to create a 50 MB partition for DR DOS and a 20 MB partition for MS-DOS
or any other DOS I want to test (like PC DOS, PTS-DOS).
The third partition has been made bootable with "format c: /s /q". I've
also rewritten the MBR using "fdisk /mbr". All partitions are formated.
The first two partitions are otherwise empty.
I've also used Linux's dd (e.g. "dd if=/dev/sdc1 bs=512 count=1
of=bootsec1.bin") to check if the boot signature 55AA is present on all
partitions + on the MBR and it is.
Thinking logically: If the BIOS wouldn't check, it should boot. The MBR
code should find the active partition #3 and chainload the bootsector.
This should include the bootcode for FreeDOS, since I've formated it
with /s and the system files are on the parition.
I hate it when a BIOS checks stuff that it rather shouldn't care about!
Any other error message and it could have been FreeDOS, but I am sure
this one if from the BIOS _before_ it executes the MBR boot code.
Maybe the next time I will try only one partition first... Anyway:
again, I've come to a halt for now.
I appreciated your help.
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