For older systems (esp. 286) you'll likely need to be using the XT-IDE bios extension to use a 2GB CF card.

I just went through getting a CF card to work with a 286 build. I ended up using a lo-tech XT-IDE adapter card to load the XT-IDE bios, and connected a the CF card via a IDE-CF adapter to the computers 16-bit ISA controller card.

I haven't tried it with a 2GB card, but a 1 GB card did work.

I think the same.

In the late 90s, some LBA Enhancer cards existed (ISA card with an EPROM).

They might be an alternative to XTIDE Universal BIOS, but maybe need a 386/486 processor..

tony359 wrote on 2022-10-02, 15:09:

Is 2GB ok for an old msdos 6.22 and a, say, 286 system?

Hi there! Yes, it is okay, don't worry.
- The largest CF you can use without worrying is 8GB.

That's the maximum disk size which MS-DOS can handle no problem.
Past this size, weird things can happen. But don't have to happen. Depends on BIOS and other factors.

An 8GB disk/card can be divided into 4 partitions with 2GB each.
In practice, an 8GB disk/card is a bit smaller, maybe (7.xx GB), don't worry.

Thanks both

Can you remind me why a 2GB CF won’t work on a 286 without XTIDE while my old HDD will?

Thanks

tony359 wrote on 2022-10-02, 16:48:

Thanks both

Can you remind me why a 2GB CF won’t work on a 286 without XTIDE while my old HDD will?

Thanks

It has to do with limitations in older BIOSs in how hard drives are configured.

In the case of user-definable hard drives, you'd typically run into a limit based on heads, cylinders and sectors which combined to create a 504MB maximum capacity. In the case of BIOSs which didn't have user-defined types (such as the 286 BIOS on my recent build), you're even further limited to whatever pre-defined types are available.

Therefore you need a BIOS extension like XT-IDE to be able to properly assign larger capacities.

Shponglefan wrote on 2022-10-02, 18:21:

It has to do with limitations in older BIOSs in how hard drives are configured.

In the case of user-definable hard drives, you'd typically run into a limit based on heads, cylinders and sectors which combined to create a 504MB maximum capacity. In the case of BIOSs which didn't have user-defined types (such as the 286 BIOS on my recent build), you're even further limited to whatever pre-defined types are available.

Seconded. Even with user-defined HDD parameters available in BIOS, they might still be limited to 528MB / 504MiB. If you went through all the troubles of resurrecting a 386 or earlier system, why not look for smaller CF cards with better compatibilities as well?

While 2GB was the largest single partition FAT16 can handle, HDD of that capacity were very rare in and before 1995 (when Pentium were becoming more and more common) so I wouldn't be surprised if a 286/386 motherboard could not recognize one.

Exactly my thought. I think I’d rather get a 256GB one (which is plenty for a 286!) so it works everywhere.

I can then also have the 2GB one for more modern systems with windows etc. but the testing one can totally be a 256MB one.

Any recommendations on type, brand etc?

(Alternatively an XTIDE board which would bypass the bios limitations altogether of course. )

Just a note... for 286 use real DOS (6.2 or 6.22). With Win9X DOS it won't boot. This also applies to real HDDs.

If the 2gb is too large maybe a DDO work? This person used EZ-Drive on their 286 and worked for them: SOLVED - Help getting IDE to boot on a 286

tony359 wrote on 2022-10-02, 20:32:

Exactly my thought. I think I’d rather get a 256GB one (which is plenty for a 286!) so it works everywhere.

I can then also have the 2GB one for more modern systems with windows etc. but the testing one can totally be a 256MB one.

Any recommendations on type, brand etc?

256GB? 😆 That's still plenty for a modern system, as long as you don't install too many games. 😉

For the record, MS-DOS 4.0/4.01 introduced 2GB partition but was buggy and memory hungry; most users (myself included) stuck with 3.30 which was only capable of 32MB partition. It was not until the revolutionary 5.0 (2GB partition + multiple startup configurations + HIMEM.SYS and EMM386.EXE + QBasic replacing GWBasic, etc.) did the 2GB (max) partition become more common. My first Pentium desktop in 1995 had only an 1GB Quantum Fireball.

Buying new old stock or tested industrial-grade CF cards of big brands (Sandisk, Kingston, etc.) with 512MB or less can by expensive; if you've got flea markets or e-waste centers nearby you might be able to salvage 512MB or smaller CF cards for free or with very low price. And a small tip: perform FDISK and FORMAT with a real DOS (5.0-6.22) instead of using a modern system.

I love MS-DOS 5.. It's so weird. 😁 ❤️

https://www.youtube.com/watch?v=dmEvPZUdAVI

dormcat wrote on 2022-10-02, 22:55:

tony359 wrote on 2022-10-02, 20:32:

Exactly my thought. I think I’d rather get a 256GB one (which is plenty for a 286!) so it works everywhere.

256GB? 😆 That's still plenty for a modern system, as long as you don't install too many games. 😉

🤣! I keep doing that!

Buying new old stock or tested industrial-grade CF cards of big brands (Sandisk, Kingston, etc.) with 512MB or less can by expensive; if you've got flea markets or e-waste centers nearby you might be able to salvage 512MB or smaller CF cards for free or with very low price. And a small tip: perform FDISK and FORMAT with a real DOS (5.0-6.22) instead of using a modern system.

What's the advantage of an industrial CF card?
And yes, I will definitely prepare the card on an actual system.

Also thanks for the heads up about using actual DOS and not Windows DOS.

TBH I'm thinking of getting a network card for XT-IDE. I believe that even a smaller CF might struggle to get recognised on some older and quirk systems so maybe an XTIDE is the solution.

Thanks all for now!

Little help please.

I couldn’t find the 2GB card I thought I had and I only found a 4GB one instead.

I partitioned it on a socket 7 board under dos 6.22, worked, transferred the system and all the files but wouldn’t boot.

Tried again, removed the partition, installed DOS via floppy from scratch, all works fine but then it refuses to boot up.

If I boot up from another disk I can access the CF no problem and run software from it.

BIOS can detect it correctly as a 4GB drive.

What could that be? I feel it might be something silly I’m forgetting 🙂

Thanks

Did you set the active partition in FDISK after creating it? That gets overlooked sometimes.

tony359 wrote on 2022-10-03, 21:25:

Little help please. […]
Show full quote

Little help please.

I couldn’t find the 2GB card I thought I had and I only found a 4GB one instead.

I partitioned it on a socket 7 board under dos 6.22, worked, transferred the system and all the files but wouldn’t boot.

Tried again, removed the partition, installed DOS via floppy from scratch, all works fine but then it refuses to boot up.

If I boot up from another disk I can access the CF no problem and run software from it.

BIOS can detect it correctly as a 4GB drive.

What could that be? I feel it might be something silly I’m forgetting 🙂

Thanks

This happened to me once; use FDISK to check if your partition has been set active.

Screencap taken from https://www.blackviper.com/2002/10/06/fdisk-usage-guide/

UPDATE: digistorm beats me. 😉

tony359 wrote on 2022-10-03, 21:25:

What could that be? I feel it might be something silly I’m forgetting 🙂

Thanks

It's possible it doesn't have a master boot record.

Try FDISK /mbr

Shponglefan wrote on 2022-10-03, 21:38:

It's possible it doesn't have a master boot record.

Try FDISK /mbr

That worked! Thank you! I did read about that but I had forgotten to try!

Can I ask why that is a necessary step?

Thanks again!

tony359 wrote on 2022-10-03, 21:53:

That worked! Thank you! I did read about that but I had forgotten to try!

Can I ask why that is a necessary step?

Thanks again!

If the master boot record hasn't been created properly on the drive (or CF card), it can't be used to boot up the system.

The FDISK /MBR command rewrites the master boot record and thus allows the drive to be used for booting.

Thank you!

I understand that part - but shouldn't that happen automatically when the CF is partitioned?

Did you use overlay software to make it work under 286?
I'd recommend it as it is going to cost you nothing, while XT/IDE is not cheap.

tony359 wrote on 2022-10-04, 20:58:

Thank you!

I understand that part - but shouldn't that happen automatically when the CF is partitioned?

Not always, fdisk should ask if you wish to make first partition active.