DOS ain't dead

> Correction: SvarDOS SvarCOM was developed from scratch and modeled after
> MS-DOS 5.x/6.x command.com. A few more details are on
> http://www.svardos.org/svarcom/

Oh, ok. Thank you for correction.

> Could be some weird CF geometry, sometimes it mismatched when using
> different connections for CF like various adapters.

I also think this could be the case.

> Also it might installed MBR for LBA? Where did you SYS your drive? Inside BOOK or on other PC?

I tried it on the Book. I also tried it from DOSBOX-X by mounting a raw drive from within it on Linux. But results were similar.

> It would be better to do it on BOOK, boot FD from some other media and
> prepare CF there...

Not much choice here. It does have an external 8-bit ISA extension board, but I don't have any floppy controllers to plug in it. And I don't know if it can boot from it, even if I had one.

> WARNING: using suspect partition Pri:1 FS 06: with calculated values
> 988-1-63 instead of 61-254-63
> C: HD1, Pri[1], CHS = 0-1-1, start= 0 MB, size = 486 MB

Hm, looks like typical mismatch when disk is partitioned and formatted with different CHS than readed later...

---
DOS gives me freedom to unlimited HW access.

> > > XT-class BIOSes don't usually support LBA, so the DOS kernel has to
> use
> > CHS
> > > to access the sectors on the disk.
> > >
> > > Many DOS implementations (probably at least FreeDOS and MS-DOS, not
> > sure)
> > > detect the disk geometry from the information in the FAT boot sector,
> so
> > > you cannot just write any random filesystem image to the SD card with
> > > Linux's dd command and expect it to work properly.
> > >
> > > When creating the filesystem you need to use the same geometry that
> the
> > > Book8088's BIOS uses.
> > >
> > > At least MS-DOS and FreeDOS also require that the disk is partitioned.
> > The
> > > starting sectors of the partitions in the partition table also need to
> > be
> > > compatible with the actual geometry.
> >
> > you can test it with 86box, with 8088 machine with XT-IDE and a disk
> image
> > with CHS=1006/16/63, partitioned and formatted with DOS 3.31, and boot
> with
> > FreeDOS 2043-86 kernel (F16/F32 doesn't matter) and you can get same
> > error:
> >
> > (I even tried latest snapshot uploaded in github, but it makes no
> > difference)
>
> There may also be something wrong with FreeDOS. I noticed that for some
> reason ST-DOS's partition mounter can parse logical partitions that are
> created with MS-DOS 6.22, but it has problems parsing logical partitions
> that are created with FreeDOS. FreeDOS is probably not fully following the
> specification of the MS-DOS partition table. FreeDOS doesn't have problems
> parsing partition tables that are created with its own FDISK though.
>
> FreeDOS is clearly doing something differently than MS-DOS, but I haven't
> investigated what exactly is the difference.
>
> Different versions of MS-DOS also create different partition tables and
> parse them differently, and they may not be 100% compatible with each
> other. MS-DOS 3.31 is a relatively old version, and FreeDOS only aims to be
> compatible with MS-DOS 6.22.
>
> I recommend at least creating the partition tables and filesystems with the
> same operating system that is going to use them.

same HD image booted with QEMU and DOS 6.22 shows no problem:

> > you can test it with 86box, with 8088 machine with XT-IDE and a disk
> image
> > with CHS=1006/16/63, partitioned and formatted with DOS 3.31, and boot
> with
> > FreeDOS 2043-86 kernel (F16/F32 doesn't matter) and you can get same
> > error:
> >
> > (I even tried latest snapshot uploaded in github, but it makes no
> > difference)
>
> Can you upload an image like that? If it fails in 86box on a Linux host too
> I could try to debug it.

if you have uudecode and xdelta3, you can create one yourself:

1. create empty file with specified size
`dd if=/dev/zero of=512M_CF.null bs=16384 count=31689`

2. save below block as `512M_CF.uue` and run `uudecode 512M_CF.uue` to generate `512M_CF.xdt`
->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-

begin 644 512M_CF.xdt
MUL/$``0:-3$R35]#1BYI;6<O+S4Q,DU?0T8N;G5L;"\$A6^$@(```(4$3!(C
M4"[@^C/`CM"\`'R+]%`'4!_[_+\`!KD``?*EZAT&``"^O@>S!(`\@'0.@#P`
M=1R#QA#^RW7OS1B+%(M,`HON=!J`/`!T]+Z+!JP\`'0+5KL'`+0.S1!>Z_#K
M_K\%`+L`?+@!`E?-$U]S##/`S1-/=>V^HP;KT[["!K_^?8$]5:IUQXOUZ@!\
M``!);G9A;&ED('!A<G1I=&EO;B!T86)L90!%<G)O<B!L;V%D:6YG(&]P97)A
M='-Y<W1E;0!-:7-S`(`!`0`&#__M/P```.%X#P!5J@#K*)!)0DT@(#,N,P`"
M$`$``@`"``#X^``_`!``^C/MN,`'CMC$'AP`B!;]`0K2>0B)'B0`C`8F`([%
MCM6\`'S\'C;%-G@`ORI\N0L`\Z0?Q@8N``^_>`"X*GRKD:O[BA;]`<T3H!``
MF/<F%@`#!@X`Z',`Z'D`NP`%4^B@`%^^<0&Y"P"0\Z9U5X/'%;$+D$PFBT<<
MF8L."P`#P4CW\3T4`'\"L!26H1$`L033Z.@R`/\V)`#$'FT!Z#``Z%L`*_!V
M#>@=`%+W)@L``]A:Z^E;BBX5`/\N;0&^BP'K5)`!!B0`$2XF`,.A&`#V)AH`
MD:$D`(L6)@#W\9*+#A@`]O$JS)'^Q8;IT,[0S@KQAO*'RL._!0"X`0+-$W(#
ML`'#@/P1=/CJOM4!Z!T`OJL!Z!<`,\#-%C;'!G($-!+J``#__[0.NP<`S1"L
M/"1U],,``'``24\@4UE335-$3U,*#4YO;BU3(&1I<VL@;W)E<G)O<B0*#5)E
M<&QA8V4@86YD('-T<FEK>2!K97D@=VAE;B!R96%D>0H-)`H-1&)O;W0@9F%I
M;'5R920@@%6J^/___P``_P`!/!4!=B0,(Q4`@6,0`#$#`('X``$<3@%S)`%%
M)`$\)`$3%@$Q)0DF)`AE"28!&20!%B0.`!0(`(???#.'X```@8```*Z\``"#
MOX0`+`H9@AD+>D!L`0N"85`("S=I!!*$@(````$%``>```$``(2`@``$$H2`
M@````04`!X```0``A("```02A("````!!0`'@``!``"$@(``!!*$@(````$%
M``>```$``(2`@``$$H2`@````04`!X```0``A("```02A("````!!0`'@``!
M``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`@````04`!X```0``A("`
M``02A("````!!0`'@``!``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`
M@````04`!X```0``A("```02A("````!!0`'@``!``"$@(``!!*$@(````$%
M``>```$``(2`@``$$H2`@````04`!X```0``A("```02A("````!!0`'@``!
M``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`@````04`!X```0``A("`
M``02A("````!!0`'@``!``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`
M@````04`!X```0``A("```02A("````!!0`'@``!``"$@(``!!*$@(````$%
M``>```$``(2`@``$$H2`@````04`!X```0``A("```02A("````!!0`'@``!
M``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`@````04`!X```0``A("`
M``02A("````!!0`'@``!``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`
M@````04`!X```0``A("```02A("````!!0`'@``!``"$@(``!!*$@(````$%
M``>```$``(2`@``$$H2`@````04`!X```0``A("```02A("````!!0`'@``!
M``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`@````04`!X```0``A("`
M``02A("````!!0`'@``!``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`
M@````04`!X```0``A("```02A("````!!0`'@``!``"$@(``!!*$@(````$%
M``>```$``(2`@``$$H2`@````04`!X```0``A("```02A("````!!0`'@``!
M``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`@````04`!X```0``A("`
M``02A("````!!0`'@``!``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`
M@````04`!X```0``A("```02A("````!!0`'@``!``"$@(``!!*$@(````$%
M``>```$``(2`@``$$H2`@````04`!X```0``A("```02A("````!!0`'@``!
M``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`@````04`!X```0``A("`
M``02A("````!!0`'@``!``"$@(``!!*$@(````$%``>```$``(2`@``$$H2`
M@````04`!X```0``A("```02A("````!!0`'@``!``"$@(``!!*$@(````$%
M``>```$``(2`@``$$H2`@````04`!X```0``A("```02A("````!!0`'@``!
:``"$@(``!!*#R8````$%`$:N``$``(/)@```
`
end

->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-->8-

3. get/install/compile `xdelta3`, and run `xdelta3 -d -s 512M_CF.null 512M_CF.xdt 512M_CF.img`

then you should able to boot it on 86box(A drive with FreeDOS, and 512M_CF.img [CHS=1006/16/63] as IDE 0:0, press "a" key on XT-IDE boot delay prompt)

> > The biggest problem is that FreeDOS fdisk didn't work on the machine. So
> it
> > wasn't possible to partition the disk on the machine.
>
> I will prepare a fix for FDISK. Theoretically there is command line
> parameter /x to disable LBA. Problem is, that the BIOS gets
> queried for LBA support even if LBA is disabled. And that is a problem if
> INT13,41h is broken.
>
> I will modify FDISK such LBA that support is not even queried if LBA is
> disabled via /x parameter.

A modified FDISK is uploaded to https://nextcloud.iww.rwth-aachen.de/index.php/s/D4sEZfG7LmHeWqy

This hopefully works on the Book8088 if started with parameter /x. At least this works for me under 86Box with Xi8088 machine and XT-IDE. It previously did not.