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First post, by MajinPowers

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I am trying to get a IDE to SD card running in my 486 PC. I can install the adapter with a 2GB SD card and the BIOS see it.

The BIOS enters:
Ctlinders: 3880
Heads: 16
Sectors/Tracks: 63
Landing Zone: 3880
Write Precomp: None

When I use the MS-DOS 6.22 boot disk and create the primary DOS partition The PC asks me to reboot.
After the reboot he PC can see drive C: but when I try to format the drive I get the error "Error writing FAT. Format terminated".

If I try to use fdisk with a Windows 98 Boot disk the same thing happens but I get the error "Unable to write BOOT.".

I have tried different IDE cables with no luck.

I am able to get a 128GB SD card running using Ontrack Disk Manager 9.57 but it makes my Gotek no able to boot when using spacebar. just says everything is not a system disk. Just stating this because I think it has to be something with the 2gb SD setting the bios is auto detecting.

Any help is much appreciated.

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Last edited by MajinPowers on 2021-11-14, 01:52. Edited 2 times in total.

Reply 1 of 11, by jakethompson1

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What settings are in the BIOS for the disk?
Sometimes the BIOS doesn't support LBA, but will let you set a number of cylinders > 1024. That could cause issues like you are seeing.
Does the BIOS have any "LBA", "Large", "Large Disk Access Mode" type settings?
If not, and you don't want overlay software, you could set 1024 cylinders, 16 heads, 63 sectors, 65535 wpcomp, 1024 landing zone and just use it as a 504MB disk.

Reply 2 of 11, by MajinPowers

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Updated the first post with more information.

The Bios does have a section for LBA Mode Control. It is set to disabled currently.

If the BIOS can see a 2GB drive does that mean it is supported? I would like to use the 2GB if possible.

Any way to check an SD card for the Cylinders - Heads - Sectors - Landing Zone - and Write Precomp?

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Reply 3 of 11, by jakethompson1

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That's it, set LBA mode control to enabled and it should work.
Old Phoenix BIOSes have some bugs with disks of various sizes, but I think a 2GB drive is below those limits.
The autodetected settings look plausible. The issue is that the interface between DOS and the BIOS can't handle more than 1024 cylinders, but can handle up to 255 heads, so "LBA Mode Control" tells the BIOS to trade fewer cylinders for more heads (and reverse that process when talking to the drive).

Make sure to repartition the drive after making that change; perhaps do an fdisk /mbr first for good measure.

Reply 4 of 11, by Pierre32

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MajinPowers wrote on 2021-11-14, 01:49:

Any way to check an SD card for the Cylinders - Heads - Sectors - Landing Zone - and Write Precomp?

This is a handy tool for checking drive geometry. I've used it for CF cards. https://archive.org/details/whatide

Reply 5 of 11, by MajinPowers

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That fixed it!
I also had to set multi-sector transfers to auto.

Thank you jakethompson1 for the help!

Sort of non related but, I also ordered a DoubleROM - IDE Size Limit Remover - Dual Bootable ROM ISA Card from MonoTech.
My understanding is this will allow me to use any size HDD. Is that correct?

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Last edited by MajinPowers on 2021-11-14, 02:31. Edited 1 time in total.

Reply 6 of 11, by MajinPowers

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Pierre32 wrote on 2021-11-14, 02:08:
MajinPowers wrote on 2021-11-14, 01:49:

Any way to check an SD card for the Cylinders - Heads - Sectors - Landing Zone - and Write Precomp?

This is a handy tool for checking drive geometry. I've used it for CF cards. https://archive.org/details/whatide

Thank you I will check that out.

Reply 7 of 11, by Horun

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MajinPowers wrote on 2021-11-14, 02:29:

Sort of non related but, I also ordered a DoubleROM - IDE Size Limit Remover - Dual Bootable ROM ISA Card from MonoTech.
My understanding is this will allow me to use any size HDD. Is that correct?

Well up to the max size the ROM is programmed too. DOS still has a 2GB FAT16 max partition size...

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor.

Reply 8 of 11, by MajinPowers

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Horun wrote on 2021-11-14, 03:17:
MajinPowers wrote on 2021-11-14, 02:29:

Sort of non related but, I also ordered a DoubleROM - IDE Size Limit Remover - Dual Bootable ROM ISA Card from MonoTech.
My understanding is this will allow me to use any size HDD. Is that correct?

Well up to the max size the ROM is programmed too. DOS still has a 2GB FAT16 max partition size...

Can you not use DOS 7.1 and go to 128?

Reply 9 of 11, by maxtherabbit

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MajinPowers wrote on 2021-11-14, 02:29:

That fixed it!
I also had to set multi-sector transfers to auto.

That checks out, most CF cards will not support multi sector transfers

Reply 10 of 11, by MajinPowers

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Got the MonoTech DoubleROM - IDE Size Limit Remover yesterday and got it installed today.
I was able to use a 128GB SD card with the new BIOS (On the DoubleRom).
I also installed 128k Cache on the board as well and maxed out the RAM to 64MB!

The manual only showed 128k cache as an option. Are some chipsets / motherboards not able to go to 256k?

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Reply 11 of 11, by jakethompson1

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MajinPowers wrote on 2021-11-26, 02:57:

The manual only showed 128k cache as an option. Are some chipsets / motherboards not able to go to 256k?

Upload a picture of the board? We can guess depending on whether there are four+one or eight+one sockets, and whether they are 28-pin or 32-pin or a mix of both.
128K is not going to be enough to cache 64MB, something to keep in mind if you run Windows which allocates memory from the top down and will use noncached memory first.