Just want to add on thing - I checked the installed files on the CF card on another system. They look correct (e.g. all files are there and filesize, for example of the command.com, seems to be also correct)

You might have to keep trying with more, older cards 🙁 This sounds like typical glitchiness of more modern CF cards never validated for IDE work.

Ok - here is what I tried next:

- I used an older (256MB BUFFALO RCF-X) CF card from a different system with DOS already installed - and that WORKED without problems!
- Next I bought the very same CF card model again (256MB BUFFALO RCF-X) and installed DOS - same Error at 99%
- I installed DOS to the new card on the other working system (from which the working CF card came) - not booting
- I cloned the working CF card to the new CF card - not booting
- I used Phils DOS-Boot Disk (https://www.philscomputerlab.com/dos-boot-dis … -easy-fast.html) - not booting

Im running out of ideas.... 🙁

leave the old buffalo card in this system, use new card in the other? 😜

Aui wrote on 2024-01-15, 04:47:

Ok - here is what I tried next: […]
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Ok - here is what I tried next:

- I used an older (256MB BUFFALO RCF-X) CF card from a different system with DOS already installed - and that WORKED without problems!
- Next I bought the very same CF card model again (256MB BUFFALO RCF-X) and installed DOS - same Error at 99%
- I installed DOS to the new card on the other working system (from which the working CF card came) - not booting
- I cloned the working CF card to the new CF card - not booting
- I used Phils DOS-Boot Disk (https://www.philscomputerlab.com/dos-boot-dis … -easy-fast.html) - not booting

Im running out of ideas.... 🙁

1. Make sure you’re using the latest BIOS firmware
2. Try different hard disk modes in the BIOS (EG turn LBA mode on or off). I have similar issues with my 486 reading CF cards when LBA mode is enabled.

I don't think there were any firmware updates publicly released for the DECpc line - doing one might require finding someone else with the same machine that has a newer BIOS. OP isn't super clear on what exactly the "Dec Pc 466d2" they've got is though - there were a few models some of which are newer than others.

I've got a DECpc LPv+ 466d2 here with PhoenixBIOX A486 Version 1.01.02 (DECpc LPv+ 486DX2 Version 1.03). The LPv+ line was released on 17 January 1994 and replaced by the new Venturis line on 1 November 1994.

I've just unplugged its two tiny spinners (202MB and 162MB) and given it a CF card reader for testing. By default it couldn't sensibly detect a 1GB CF card, but switching the Large Drive Addressing option over on Page 2 from Standard to LBA Convert fixed this.

The CF card I gave it was a Transcend Ultra 1GB Industrial previously used for testing Windows 98 on a Digital PC 3500 (Pentium II) and the DECpc LPv+ 466d2 couldn't boot from it for whatever reason. So I installed MS-DOS 6.22 and it installed just fine with no errors but the machine clearly doesn't like it much - it took a very long time to get as far as "Starting MS-DOS...".

I gave up after a few minutes and gave it another CF card, a 256MB Kingston KCF256M-KT3B6HFA, that has OS/2 2.0 installed from a Digital Celebris 5133ST. The DECpc detected and booted that just fine without any trouble

So while the machine appears to work fine with ~1GB drives, and the CF card adapter works fine (booted from the 256MB card), so the CF card is probably the issue. Given someone reported difficulties with a 13GB hard disk over on vcfed, perhaps the speed of the drive matters.

EDIT (13 days later): For anyone in the future who stumbles on this thread with an LPv+ machine, it looks like the Large Drive Addressing option was introduced in a BIOS revision - not all machines have it.

• DECpc LPv+ 450d2, built May 1994, banner "DECpc LPv+ 486DX2 Version 1.00" - No large drive addressing setting
• DECpc LPv+ 466d2, built June 1994, banner "DECpc LPv+ 486DX2 Version 1.03" - has the large drive addressing setting

Thanks a lot ! This is bringing at least some light to the problem. The machine I have is very similar in most respects - except - the LBA setting is missing. This may be just the explanation.
In the meantime I have tested a 425 MB physical HDD and that worked without problems. So maybe I will need a CF card which is immune to any LBA compatibility issues...

Kind of surprised the LPv is missing that setting! There is only about 5 months between the two models - the LPv was announced 30 August 1993 while the LPv+ was 17 January 1994. As far as I can tell the only (advertised) difference is that the LPv+ adds "Energy Star-compliant power management".

I wonder if its a BIOS revision thing, or a model thing. The LPv/LPv+ service manual doesn't even mention the LBA setting at all which makes me wonder if there was a BIOS update at some point that added it; the machine I have here was made in June 94. Sadly I don't have my LPv or other LPv+ here with me to check if they're any different.

Also, in case you've not found them already and they're of any use:
DECpc LPv/LPv+ Service Maintenance Manual and Service Guide
DECpc LPv drivers (pretty much just for the onboard S3 805 video)

Thanks - I tried a really old 8MB (!) CF-card and that worked with no issues. It shows that the CF card type matters but now its no fun to use that machine...

Well, if it was me (or more like when its me - I've got a bunch of DECpc LP/LPv/LPv+ awaiting restoration and I doubt they all have good HDDs in them) I'd either :

• go with the small 256MB known working CF card and use a network drive for everything else - I use NetWare, but perhaps mTCP NetDrive is an easier option.
• Install a SCSI card and use something like BlueSCSI to emulate whatever size drive you like, plus a CD-ROM drive.