Boot from a DOS boot floppy, and run

fdisk /mbr

Yes... Try "FDISK /MBR" and load up fdisk, and check if the primaery partition is set to active.
Some old systems have some issue on not setting the partition as active.
I just don't remember if it is when you create one single primaery or when you create a primaery + extended + logic.

In my case it is a single primary partition - thanks, I'll try as soon as possible as you advised me

Yeah.... I overlooked the "non-active" partition, back in early 1995. The result was that I flunked basic computer knowledge that day at school. I can tell you, that I shure learned from my mistakes. 🤣 🤣 🤣

EDIT:
Just to cross-check everything. Pop that CF-solution into a more modern system, and let the bios automatically find the drive parameter's, or use the build in HDD search tool in the BIOS. Write them down, and use them in the 486-bios. Just to be shure it is all set correctly up.

If that still doesn't help, you can install Ontrack Dynamic Drive Overlay in MBR or something like this.

brostenen wrote:

EDIT:
Just to cross-check everything. Pop that CF-solution into a more modern system, and let the bios automatically find the drive parameter's, or use the build in HDD search tool in the BIOS. Write them down, and use them in the 486-bios. Just to be shure it is all set correctly up.

A good tip. I was actually wondering how one does determine the parameters of different compact flash cards when using it in this manner.

Can anyone perhaps recommend which solution works the best (the external one that you attach with a bracket or the internal one), which shops or sellers to buy from and what else one should look out for?

Had fun trying to find such parameters for my DX-33, incidentally, 993 16 63 for my 512MB model but they can all be different. I ended up looking up a datasheet for it in the end, but not all cards have this.

I have yet to own an adapter that doesn't work, perhaps I have been lucky. Given the CF interface is practically IDE anyway I'm amazed at the idea someone designing such a simple device could mess it up, but it doesn't really shock me anymore after some of the mistakes I've seen made in this industry.

After trying in every way, I came to the conclusion that this adapter/CF Sandisk 2GB combo cause problems with this motherboard/BIOS... I tried in every way you have advised me, I eventually solved by using a 128mb Verbatim CF, waiting to take another larger one - have you ever had problems with this particular model of CF?

I had similar problems with my VLB 486, detects 8GB drive fine but hangs during post. Happens with any of my 8GB HDD's not just CF cards so came to the conclusion the controller cant handle 8GB even though it detects ok.

Yeah, dito. The BIOS reporting the size correctly doesn't necessarily mean it's supported.

oerk wrote:

Yeah, dito. The BIOS reporting the size correctly doesn't necessarily mean it's supported.

Exactly. Happened to me once with an 386. It was detecting all the parameters correctly, but wouldn't allow me to use it. If there is no LBA support in the BIOS, forget about using anything bigger than 528MB (or something like it, changes with calculation method).

On a 486 I struggle to fill a single 2GB partition anyway. I tend to favor the common Kingston cards and I've never had one not work, in various sizes too.

For reference sake, these ones;

Only once did I have one not work, but that was down to me writing a disk image in a modern PC. No idea why, perhaps the BIOS handled the drive geometry differently, but installing DOS with the computer itself worked first time and in the two subsequent times I have had to do it so far - and probably when I have to do it again in the future. Don't ask, the machine is more trouble than its worth most likely, but I like it all the same.

It is usually best to partition and format drives in the machine it will be installed, because of differences in BIOS support for large drives.

Large drives, greater than 1024*63*16 sectors (504 binary megabytes or 528 decimal megabytes) need geometry translation to be supported.

If other machine supports LBA and the other does not, or if the two BIOSes translate the geometry differently, it won't work between the machines or USB readers.

Can you post a link to CF card datasheet, or tell its physical geometry reported by the drive itself, and logical geometry seen by DOS in the target machine?
Perhaps there is a way to manually set the parameters so that the card will work in DOS, but depending on physical geometry, it may not reach full 528 MB.

It appears at least there is some Transcend industrial grade compact flash series cards that should be quite compatible. Smaller cards than 16GB always report 16 heads while the 16GB model reports 15 heads. All report 63 sectors. So with all cards up to 512MB (decimal megabytes), you can use the whole card (geometry X*63*16). For cards 1GB to 8GB, you can get the whole 528 decimal megabytes because BIOS limits to 1024 cylinders, 63 sectors and 16 heads. For 16GB card, because it has only 15 heads, you are limited to 1024*63*15 sectors or 495 MB.

I used to have some 850MB Maxtor drive in a 486dx4/100, I don't recall if the AMI Winbios BIOS supported LBA, but at least it was able to translate the geometry for DOS.

tayyare wrote:

oerk wrote:

Yeah, dito. The BIOS reporting the size correctly doesn't necessarily mean it's supported.

Exactly. Happened to me once with an 386. It was detecting all the parameters correctly, but wouldn't allow me to use it. If there is no LBA support in the BIOS, forget about using anything bigger than 528MB (or something like it, changes with calculation method).

Happened to me on a Slot 1 machine. Gigabyte board, BIOS does detect 120 GB drive, but hangs after POST when displaying that BIOS table with memory and drive data. I think 60 GB and less and it works 😀

Regarding getting the drive specifications, there is a DOS tool that can do this. I forgot the name of it, I found someone on YT demonstrating it. It will tell you the CHS.

PhilsComputerLab wrote:

tayyare wrote:

oerk wrote:

Yeah, dito. The BIOS reporting the size correctly doesn't necessarily mean it's supported.

Exactly. Happened to me once with an 386. It was detecting all the parameters correctly, but wouldn't allow me to use it. If there is no LBA support in the BIOS, forget about using anything bigger than 528MB (or something like it, changes with calculation method).

Happened to me on a Slot 1 machine. Gigabyte board, BIOS does detect 120 GB drive, but hangs after POST when displaying that BIOS table with memory and drive data. I think 60 GB and less and it works 😀

Regarding getting the drive specifications, there is a DOS tool that can do this. I forgot the name of it, I found someone on YT demonstrating it. It will tell you the CHS.

There are so many HDD size limits all documented in following links:

http://www.hardwaresecrets.com/hard-disk-driv … acity-limits/6/
http://www.tldp.org/HOWTO/Large-Disk-HOWTO-4.html
http://www.dewassoc.com/kbase/hard_drives/har … ze_barriers.htm

When it comes to hardware/BIOS related limits, the most common (according to my experience) are the following:

528MB: Most of the 386 boards and some older 486 boards (can be solved by overlay software like Ontrack)
8GB: Most of the 486 and some early Pentium boards (can be solved by BIOS update, if available, or Ontrack)
32GB: Most of the Pentium (socket 7) and some early PII boards (mostly can be solved by BIOS update, if available)
128GB: Some PIII boards (mostly non-Intel and Intel pre 8xx chipsets) and earlier boards.

And most common OS related (partition size) limits are of course 2GB DOS 6.x (FAT 16) limit, 32GB Windows 95B/C limit and 120 GB Windows 98 (FAT 32) limit.

My DFI super socket 7 board takes a 120 GB drive just fine. I've got Windows 98 SE installed on it.