Getek works well.

I don't think CF was electrical designed to be removed under power (anyone know? for sure) In particular, I don't know the power pins are shorter, to guarantee loss of power before disconnect.

If your main goal is just to avoid power-down, I'd probably do something like:

- put a power switch on the CF interface, so you can power-down before removing.

Ctrl-Alt-DEL - this will insure any cached butters etc. are written - while the system reboots,
power-off CF card and remove - just be fast enough that DOS hasn't started enough to recognize the drive.
If you need extra time, hit RESET to cause a full POST.

You can prob. do the same in reverse -insert CF, power it on, reboot.

It's a game of chance and luck.
CF are made to be hot swapped and usually go fine with it. As long as you don't swap while writing ofc...

It's the controller that won't go well with it.IDE controllers are not made to hot swap. Whenever the controller discovers the drive is gone, it may freeze the system. If you're lucky, you'll put back the CF before the controller discovers it's missing.

Under DOS your chances are fair, that system is basically brain-dead until asked to do something.

Under windows you're probably very unlucky, it's probably swapping the ** out of it or haunting the CF for all kinds of files to perform background tasks. Yes, including the second drive.

waterbeesje wrote on 2025-11-01, 21:45:

Under windows you're probably very unlucky, it's probably swapping the ** out of it or haunting the CF for all kinds of files to perform background tasks. Yes, including the second drive.

Agreed completely ... the only reason I suggest the reboot method with DOS is that it doesn't access files
(unless you are doing something) - and I still suggest ctrl-alt-del as that *might* clean up better that a
hard reset - but I should have added ... do this only when DOS is stopped at the command prompt and NO
user application is running!

** I have a little DOS system in my basement that once upon a time was an AASTRA office phone system that ran
XP from built in CF reader - with DOS on the CF card, I have it powered via a remote control up on the main level,
and it boots and AUTOEXECs to a DDLINK server, giving me an easy way to stash files I might want to access in the
workshop later.

Since I wrote it - I know that DDLINK doesn't keep any files open when it's not doing a transfer... and I
don't have any disk caching software loaded on it - I power it on and off via the "power plug" several
times a week, have been doing this for months and never had any problem!

The electrical issues aside, the BIOS/DOS aren't expecting the size/geometry and partition table of one of the Int 13h drives to change on the fly, so you may need your own driver handling the D: drive rather than the built-in BIOS routines in order to gracefully handle changing the drive. There were some early Zip drives that emulate a true IDE HDD rather than using ATAPI. You'd have the same issues as with those.

CF cards can operate in PCMCIA or IDE mode. Hot-swapping in PCMCIA mode is fine as it's designed for that, as long as the OS in informed of the eject in advance so that it can flush caches, unmount the filesystem, etc. In IDE mode, it'd be like hot-swapping an IDE drive, with similar consequences such as possible data loss and electrical faults, as others have mentioned.

My guess is that it will work if:
1) the CF card is alone on its own IDE port (no other drive on the same cable)
2) you are NOT using any disk caching program (eg. SMARTDRV)
3) you only reconnect the same CF card that was there already, not a different one

Also, you probably don't want to be using the IDE port on a sound card. I have noticed that sound cards tend to have address and data lines connect straight from the IDE connector to the ISA bus without buffering.

jakethompson1 wrote on 2025-11-02, 01:26:

The electrical issues aside, the BIOS/DOS aren't expecting the size/geometry and partition table of one of the Int 13h drives to change on the fly, so you may need your own driver handling the D: drive rather than the built-in BIOS routines in order to gracefully handle changing the drive.

I don't plan on changing the drive. I only have one type card (1GB) for my 486 and they all listen to the same permanent controller setting. The bios has a 504MB limit.

I am mainly worried about the hardware.

Hi! I vaguely remember that some versions of DOS did have PCMCIA/PCCard/CardBus services/support.
Datalight ROM DOS 7.1 or PalmDOS, not entirely sure..

That requires a CF-PCMCIA adapter and an ISA card with PCMCIA slot, maybe.
Or a 90s laptop with a built-in slot. They came with different kind of "CardWare" software (card services, socket services).
Something like PhoenixCard Manager 3.20, Card Soft 3.1 etc.

Examples (?): https://www.youtube.com/watch?v=c3m1sBoL2N4
https://www.youtube.com/watch?v=FB-lc2B0Ycg

I'm just a layman here, though.