wbahnassi wrote on 2021-12-06, 14:24:

I was wondering if there was a way to get the CF Card to report 500MB of capacity to the BIOS instead of its real 4GB?

Computer won't boot? Perhaps you have Phoenix BIOS 4.03 or 4.04 ? Those bios would crash if they even tried to imagine capacities over 3277 MB.

If you have a 486sx, you should almost certaily be able to go into the bios and slelect some combination of heads/sectors/tracks to go less than <528MB and that will let your system boot. IDE remaps everything, so you can change values with impunity.

Then you can install drive overlay software to see all of the space. http://vogonsdrivers.com/index.php?catid=19

douglar wrote on 2021-12-06, 17:52:

Computer won't boot? Perhaps you have Phoenix BIOS 4.03 or 4.04 ? Those bios would crash if they even tried to imagine capacities over 3277 MB.

If you have a 486sx, you should almost certaily be able to go into the bios and slelect some combination of heads/sectors/tracks to go less than <528MB and that will let your system boot. IDE remaps everything, so you can change values with impunity.

Yeah any drive above 504MB causes the POST messages to not even appear even if the rest of the system seems to power up (mechanical HDD turns on). I've attached photos of the BIOS setup program with the versions it shows. I don't see anything above version 1.. so that's probably way older than what you were expecting? It's a 486SX 25Mhz Packard Bell Multimedia PC. The same form-factor as the flat Legend PC.

Of course if you don't get POST, then disk overlay software won't even have the chance to kick in. I also tried shrinking the volume size of a 2GB CF Card as described here (http://www.dosdays.co.uk/topics/cf_card_shrink.php) but it still didn't help with the POST situation. A 256MB CF Card is the largest one I found to work, but it suffers from the frequent freezes this whole thread started about.

stuartmcivor wrote on 2020-08-02, 07:20:

I am attempting to use a Compact Flash to IDE adapter in place of a typical hard drive but am running into an issue. It seems that when reading/writing from/to the card everything is really slow. The CF card(s) I have tried, all under 512MB, have been set up in the BIOS (Phoenix V1.00) with their correct CYL/HDS/SEC as detected by WHATIDE.COM and are recognized. I can delete/create partitions using FDISK.EXE and format using FORMAT.COM from DOS 6.22 without issue.

I found that it is not uncommon to have trouble getting some new drives on some early EIDE controllers. Seems like systems from the Late Socket 3 through Socket 7 know the lingo well enough to ask to top shelf LBA , but don't know enough to actually deal with the responses they get from ATA6/UDMA5. Curiously older systems (ISA/VLB) work fine with newer drives because they don't ask for more than they can handle.

I found I could get the (relatively) new drives to work in the old systems if the BIOS let me selected a drive mode in the last column of the Bios screen as "CHS" or "Normal" mode instead of "Auto", "Large" or "LBA". Then the motherboard doesn't ask for LBA and things go fine from there. CHS mode should alow you to use drives up to 128GB or so, depending on your bios or drive overlay.

https://www.vogonswiki.com/index.php/Storage# … compatibilities
https://en.wikipedia.org/wiki/Cylinder-head-sector

wbahnassi wrote on 2021-12-06, 18:13:

Yeah any drive above 504MB causes the POST messages to not even appear even if the rest of the system seems to power up (mechanical HDD turns on). I've attached photos of the BIOS setup program with the versions it shows. I don't see anything above version 1.. so that's probably way older than what you were expecting? It's a 486SX 25Mhz Packard Bell Multimedia PC. The same form-factor as the flat Legend PC.

OK, you don't have the option of selecting CHS mode, do you? I added your symptoms to the Storage Wiki.

Looks like you need to keep the drive at less than 504MB and install drive overlay software. http://vogonsdrivers.com/index.php?catid=19

Or if your IDE controller is ISA or VLB, you could try an option rom like XTide Universal bios ( https://www.xtideuniversalbios.org/ ) or Promise IDE MAX Bios.

Or maybe you could get lucky and find a full replacement bios like MR Bios for your system. That would be the best solution.

douglar wrote on 2021-12-06, 18:35:

OK, you don't have the option of selecting CHS mode, do you? I added your symptoms to the Storage Wiki.

Looks like you need to keep the drive at less than 504MB and install drive overlay software. http://vogonsdrivers.com/index.php?catid=19

It doesn't offer options beyond CHS configuration, so other modes are not supported. You can only cycle between preconfigured CHS Types as well as input custom values (which is what I'm doing for the 256MB CF Card).

It's strange how a 512MB CF card can totally prevent POST. But unfortunately this means any software solutions or BIOS settings won't work because they won't even have the chance to execute.

wbahnassi wrote on 2021-12-06, 14:24:

I have a 4GB CF Card but it won't work on this machine because it's larger than the limit of 504MB (machine won't even POST with such a CF Card inserted).

It should be about sectors and/or heads count, and not the size of the card per se.
I have a 1GB CF card and it works ok in the old 286 pc that can't access hdd beyond 504MB.
The BIOS even shows the size of larger CF cards correctly when you enter custom C/H/S, but will freeze/lockup if the heads count is larger than 16 (or sectors larger than 63, can't remember where's the actual bug).
Sure, what I observe is a quirk of this one specific bios on my Tomato TD60C, but your BIOS also might fail to POST for exactly the same reason.

vstrakh wrote on 2021-12-06, 20:24:

The BIOS even shows the size of larger CF cards correctly when you enter custom C/H/S, but will freeze/lockup if the sectors count is larger than 16.

Interesting. So what geometry do you use to it up to 504MB?

I got lucky with that 1GB CF card that did report 1985 cylinders, 16 heads, 63 sectors per track. Bios shows totals as 976 MB and has no problems booting dos from the first partition of 504 MB.
It seems larger cards could be used with old bioses as non-portable drive by limiting heads/sectors to 16/63. The data would be scattered around, some capacity would be wasted, and the card won't be correctly readable outside of such setup.

vstrakh wrote on 2021-12-06, 21:55:

I got lucky with that 1GB CF card that did report 1985 cylinders, 16 sectors, 63 heads. Bios shows totals as 976 MB and has no problems booting dos from the first partition of 504 MB.
It seems larger cards could be used with old bioses as non-portable drive by limiting sectors/heads to 16/63. The data would be scattered around, some capacity would be wasted, and the card won't be correctly readable outside of such setup.

Are you positive that the board had a Heads <= 63, Sectors/Track <= 16 limit ?

My experience is that Bios created before July 1994 have a Heads <= 16, Sectors/Track <= 63 limit.

Ah, sorry, messed up while writing.
Yes, it's 16 heads and 63 sectors. While the disk type is set to user-defined 47, having custom values set above those (can't test now if it was specifically heads or sectors) caused the bios to lock up.