Hi all,

maybe somebody has already experience with this. I am dealing with a very strange problem on one of my retro computer projects.

Some years ago, I bought a Commodore PC-20 II which I am currently restoring and hod-rodding a little bit.

Meaning: The half-dead hard drive (BASF 20MB - what Commodore deliverd by standard for this PC in Germany) will remain installed but inactive and is replaced by an XT-CF Lite with industrial CF Cards. The drive has some issues spinning up, but once running, it runs perfectly. Also I swapped the 8088 for a NEC V20, added an 8087 and a "Tandy" soundcard based on a kit from Russia that uses the original Lo-Tech Design, but already has the Errata corrections corrected on the new PCB layout. I also aim to disassemble the BIOS and add the code of SNDOFF which is required to mute the noise of the TI SN 76496, which the PC-JR and Tandy 1000 already has implemented.

But now to the main topic:

As said, I have installed an XT-CF Lite, jumpered to Port 300, BIOS address C800 and removed the MFM controller, which remains in an antistatic bag taped to the still installed original dying hard drive, just in case I want to reinstall the drive.

This works perfectly for:
- DOS 6.22 on an 256MB industrial CF which I have for the "leisure" part of this PC: Running old software in general
- DOS 3.2 on another of the same 256MB CF (I got me a total of 5 of these) if the XT-CF Lite is installed in a 486 (Gigabyte GA-486AM/S with AMD 5x86-P75 133)

But what does not work is to boot DOS 3.2 in exactly the same configuration in the PC-20. It will just freeze, requiring to turn the PC off and on again.

As I want to preserve the original state of this machine, it belonged to a school and has still some old school software installed including files saved from the classes that were made on this machine, I am aiming to use the original DOS 3.2 including the configuration (containing among others a school specific splash screen made from some fancy ASCII-Art echo commands and a fancy prompt), software and files for data archeology, I want this to run.

Assuming there might be an issue of size, I have ordered another CF, a Cisco/STI 32MB, but still the same. 32MB should work, 16MB might be a little small for the contents of the drive. Using a fresh DOS 3.2 disk to fdisk, format and sys the 32MB card leads to the same: No boot in the PC20, boot in more modern machines. But as said, DOS 6.22 boots perfectly from the CF in the PC20.

Any idea what could be wrong there?