Just put in 1023 cylinders, 16 heads, 63 sectors, and then fdisk/format and it should be good.

So that's all it takes? Awesome! One last question: After entering those parameters in the BIOS and formatting the drive, would I be able to take out the drive, hook it up to my PIII, write 350MB worth of DOS games to it then put it back in the 486 without worrying about data corruption?

You could also either install some overlay software or install an XT IDE BIOS card. The latter will allow you to also use larger disks or CF cards.

XTIDE BIOS rom vs EzDrive DDO

Based on my experience, there is no point of messing around with XT IDE BIOS, when EzDrive is a viable option...

Sounds good. In my 386 I have an XT IDE card and it just works. But if EzDrive works as well, it's all good.

65C02 wrote:

So that's all it takes? Awesome! One last question: After entering those parameters in the BIOS and formatting the drive, would I be able to take out the drive, hook it up to my PIII, write 350MB worth of DOS games to it then put it back in the 486 without worrying about data corruption?

With regard to this question, I think you would be fine as long as you can configure the drive identically on all the other systems in bios.

Not sure if DDO software will be convient when transferring the drive to another computer if its not used as a boot drive. You might have to install DDO on the temporary host system too.

Some notes about DDOs..
+ Great for laptops
+ Works with obscure HDD controllers
+ Works with (MS-)DOS

- Does not work CP/M-86, OS/2, Linux, Minix, Win NT or PC-MOS/386.
- May uses a special type of LBA (causes issues with exchanging data with modern platforms)
- Causes trouble with early Win95

Re: Frustrating IDE problems with 486 build, I need help
Re: SD/CF to ide CHS setup
Re: SD/CF to ide CHS setup

When you limit the geometry, you just limit the maximum addressable sector to one the BIOS is capable of enumerating. The rest of the disk is still usable if you want to cart that drive to another system. It's just that you won't be able to access it on the 486.

One caveat: I'm not 100% sure whether all BIOSes are rollover-safe, so if you try to access cylinder 1025, you may end up getting cylinder 1. (Or is it 2... I forget if cylinders are 0-indexed or 1-indexed. Either way, cylinder modulo 1024...) In that case, you might be better off not creating partitions on cylinders >1023 just in case. DOS on the 486 won't let you, but a later system would.

500MB drives are expensive on Ebay because it's the largest drive you can use on those old systems, so a lot of us want those. You can grab a 420MB for significantly less. Or a 700MB, etc.

BinaryDemon wrote:

With regard to this question, I think you would be fine as long as you can configure the drive identically on all the other systems in bios.

Right, if you put in the same geometry again it will definitely work. Even that might not be necessary, but I won't say it's 100% certain because sometimes switching between CHS and other schemes causes trouble.

If I'm not mistaken, the LBA sector is derived by a simple formula:

LBA = (CHS sector - 1) + (((CHS cylinder * heads) + CHS head) * sectors)

So as long as all systems using CHS agree there are (63 * 16) sectors per cylinder, it should equate to the same thing.

Man this forum is great! I input the drive geometry for a 500MB hard drive in the 486, formatted, moved to the PIII and entered the same drive geometry, copied my games, and moved back to the 486. So far it has been working flawlessly.

Thank you all for the help and info! 😀