Where (on what kind of computer) are you trying to use it and what SD size are you using? Maybe you're hitting some kind of BIOS limit. Also check that the adapter is correctly powered (connected to PSU and jumpers correctly set). Try with your older (and smaller) SD card, they tend to be more stable than newer cards.

An remember that maybe the problem is in your card. Check the write protection tab (although it should have failed when installing), and check your card with f3 (linux) or h2test.

its not something simple like missing the sys files? I know the MS Dos 6 update available from MS doesn't do this during the install but can be fixed by a boot floppy and typing sys a: c:

Zup wrote:

Where (on what kind of computer) are you trying to use it and what SD size are you using? Maybe you're hitting some kind of BIOS limit. Also check that the adapter is correctly powered (connected to PSU and jumpers correctly set). Try with your older (and smaller) SD card, they tend to be more stable than newer cards.

An remember that maybe the problem is in your card. Check the write protection tab (although it should have failed when installing), and check your card with f3 (linux) or h2test.

- The PC -
Computer : A Pentium II 333Mhz
Motherboard : ACCORP 6LX/EX68 SLOT 1
The BIOS is from 1999, from Award Modular, and accepts very large HDDs with auto-detection

- The Adapter -
The adapter powers on correctly and has LEDs to confirm it; it uses standard Molex or FDD connector
There are no jumpers on this thing

- The SD Card -
My original try was a 2GB card, that was well within the specs for FAT. Gave the 'DISK BOOT FAILURE' error.
I also tried a 16MB card, that was simply not detected by the adapter.
I verified the write-protect option, all my cards are write-enabled.
Installed MS-DOS without issues on a 256MB card. Gave me a 'Missing operating system' error instead.
Tested the 256MB card with h2testw without issues.

chinny22 wrote:

its not something simple like missing the sys files?

- The Install Disks -
I'm using a full installation, not an upgrade, of MS-DOS 6.22
Doing that same installation on a formatted hard disk works flawlessly

- The Data -
The two file structures (on the 2Gb and the 256Mb cards) seem identical :
[DOS]
AUTOEXEC.BAT
COMMAND.COM
CONFIG.SYS
IO.SYS
MSDOS.SYS
WINA20.386

Now since using different SD cards gave different results, I'm going to test with more and report back later today. Thank you both 😀

The original partitioning could use different geometry from your BIOS. Dos uses CHS anyway, not LBA, and the way the BIOS maps LBA to CHS may differ what from what kind of partition table the card manufacturer thought it would be nice to use as CHS parameters.

I'd try to zero out the partition table, and use LBA to get up to 2GB partitions (or then just force CHS parameters for 512MB support). Perhaps delete all partitions with fdisk, reboot, run "fdisk /MBR" to rewrite MBR code and whatever parameters, reboot, and then create a single DOS partition. Then both your BIOS and the partition table on card should use the same emulated CHS geometry.

Can think of a couple of things, reformat card with SDformatter to ensure it's got a standard format.
Or make a partition on the card - for Windows, Minitool partition manager seems to be the best way to address SD partitioning - Pro version on giveaway .. http://www.partitionwizard.com/activity/special-offer.html - though it says 8.1.1, others say this is the 9.0

from a boot disk, and after having installed MS-DOS and all of that try:

sys c:
fdisk /mbr

is your disk fat32 or fat16 ?

I have a similar problem with an sd to compact flash converter and then using the compact flash as IDE. I can access it and read/write files to it but can't seem to boot from it. Wonder if sd cards have some weird write protection on the first sector. Haven't checked yet if there's an actual valid bootsector there.

They don't have a weird write protection, but when fiddling with anything that may touch the partition table, it is possible that the card ends up being looking like a floppy (no master boot sector like fixed hard drives, starts with just partition boot sector like removable floppies).

Jepael wrote:

The original partitioning could use different geometry from your BIOS. Dos uses CHS anyway, not LBA, and the way the BIOS maps LBA to CHS may differ what from what kind of partition table the card manufacturer thought it would be nice to use as CHS parameters.

- I extended my tests to five cards : 16mb, 256mb, 2gb (no-name), 2gb (Sandisk) and 4gb.
- I have tried formatting the cards from my main PC (via USB adapter) and directly in the retro-PC (both with the DOS install, and independently with a boot disk).
- I have watched this gentlemen's video https://www.youtube.com/watch?v=G26cRjrt5Mg, who seemingly had the exact same problem as I did.
- I have stopped using auto-detection in the bios for the IDE hard drive (which often miscalculated the Cylinder, Head, etc.) and am entering specific values.
- The specific values make the hard drive detected and recognized every time (that got rid of the 'DISK BOOT FAILURE' error).
- As a result, the disk uses CHS now, for all the five cards.
- 16mb still not recognized by the adapter. 256mb and 2gb cards are detected. 4gb gives problems with FDISK because it's too large apparently.

Matth79 wrote:

Can think of a couple of things, reformat card with SDformatter to ensure it's got a standard format.

Davros wrote:

is your disk fat32 or fat16 ?

- The cards have been formatted as FAT16 both on my main PC and with a DOS boot disk on the retro machine.
- I have not tested SDformatter yet, but will try soon.

philscomputerlab wrote:

from a boot disk, and after having installed MS-DOS and all of that try:
sys c:
fdisk /mbr

- This worked, only once, on the 256mb card. But DOS didn't like it and there were apparently unknown commands in the CONFIG.SYS that were skipped.
- My boot disk was created with the same version of DOS that I'm installing, so I don't know how/why commands in CONFIG.SYS could be unknown or unrecognized.
- When I did try to reproduce this result a second time (install DOS, SYS C:, FDISK /MBR) it didn't work and gives me an 'Operating system not found'.

Harekiet wrote:

I have a similar problem with an sd to compact flash converter and then using the compact flash as IDE. I can access it and read/write files to it but can't seem to boot from it. Wonder if sd cards have some weird write protection on the first sector. Haven't checked yet if there's an actual valid bootsector there.

Jepael wrote:

They don't have a weird write protection, but when fiddling with anything that may touch the partition table, it is possible that the card ends up being looking like a floppy (no master boot sector like fixed hard drives, starts with just partition boot sector like removable floppies).

- I have the same issue as Harekiet. If I boot from the SD Card, it says 'Operating system not found'.
- It gives 'Operating system not found' even if MS-DOS is installed on the disk. And even after a SYS C: + FDISK /MBR.
- If I boot from a boot disk, then access (write, read) files on the SD Card, it works flawlessly, as a second drive.
- There seems to be an issue with the MBR on SD cards... It gets written, but does not seem to hold the changes. At least not consistently.
- When using SCANDISK on the drive, it tells me that the MBR and MBR safety copy are not identical, which reinforces my belief that MBR on SD Card doesn't work as intended.

Well that's it for now. Will continue testing stuff then report back.

I had the same problem with a 32GB card.
I switched to Dos 7.1 (from a win98se cd). Partitioned and formatted with the updated Fdisk (KB263044) and formatted as FAT32(x). This made sure that LBA was being used and it booted as the primary hard disk even with (removable disk status). There seems to be a problem using CHS when booting devices partitioned as 'removable drvies' that only contain a partition boot sector (no mbr). This applies to USB sticks as well.
The other work around I later used was to force it as a 'fixed disk' and then when partitioned it would created a mbr with a partition table (same as regular internal hard disk). This method then boots with any adaptor and any card I have used (compact flash and SD cards).
Another thing i noticed, I compared a Hama 32GB SD card and Hama 32GB Compact flash card as a primary Dos hard disk. Both cards are listed as 60MB/s max transfer rate. The compact flash card was much faster (58MB/s compared to 30MB/s for the SD and access time was 0.045 for the CF and 2.125ms for the SD). I don't know if this is because compact flash is native ide and has no translation with it's adaptor and the SD adaptors do use additional translation?
Something to keep in mind if you want the fastest disk speeds.

I boot from Sandisk 2GB and 4GB SD cards on systems ranging from a 486 VLB to a 1400MHz Pentium III. The SD adapters should have the same chipset as the one shown in the first post.
The 486 was not cooperating at first. IIRC with the original BIOS I had to manually enter Disk Parameters. A later modded BIOS fixed it alltogether. Also IIRC it mattered wheter or not I formatted and 'sys'd it from the 486 itself or while the SD Card was in another PC.

+1 for fdisk /mbr
just got my 256Mb SD card booting! thank you phil

+1 for fdisk /mbr

"People often recommend the undocumented DOS command FDISK /MBR to solve problems with the MBR.
This command however does not rewrite the entire MBR - it just rewrites the boot code,
the first 446 bytes of the MBR, but leaves the 64-byte partition information alone.
Thus, it won't help when the partition table has problems."

Source: https://www.win.tue.nl/~aeb/partitions/partit … es-2.html#ss2.7

I know it is an old post necroed by maverick85, but Jo22 is right.
The original topic sounds like a missing active partition to me.
So, activate the partition for boot.

Jo22 wrote on 2022-05-04, 06:31:

"People often recommend the undocumented DOS command FDISK /MBR to solve problems with the MBR. This command however does not re […]
Show full quote

"People often recommend the undocumented DOS command FDISK /MBR to solve problems with the MBR.
This command however does not rewrite the entire MBR - it just rewrites the boot code,
the first 446 bytes of the MBR, but leaves the 64-byte partition information alone.
Thus, it won't help when the partition table has problems."

Source: https://www.win.tue.nl/~aeb/partitions/partit … es-2.html#ss2.7

Tl;dr plx. philscomputerlabs method was effective and to the point. it runs

+1 for fdisk /mbr

I have the same adapter as Beegle with a 2GB SanDisk SD Card.
It wouldn't boot on a PCCHIPS M519 mainboard, but now it does 😀
Thanks Phil!

For the record, the MBR is not always the problem with these SD to IDE adapters (based on "Sintech" FC1307 chip).
When they initialize the chips try to find what cylinder/head/sector values to emulate, by doing the following:
a) reading the partition table (sector 0) and looking for a FAT16/32 partition
b) reading the CHS values from the FAT descriptor for that partition

If they can't find those values (due to either the partition table missing or a FAT partition not being found), they bug out and return their ATA IDENTIFY information for any requested sector read until sector 0 is rewritten.
This can make it seem like the device is working ok when you go through the routine of installing linux/windows XP/other OS that doesn't use FAT partitions, then give the dreaded "DISK BOOT FAILURE" message the next time you power the machine on.