I saw this lament in my referrer logs, of all places. Perhaps someone read it, then wondered if I had an answer? I’m not the only one searching for inexpensive flash storage for older PCs after all.

The exact solution the author sought,  a USB-IDE converter to attach a thumb drive as an IDE device, doesn’t exist as far as I know. But I can think of two things that are almost as good.

Compact flash to IDE

flash storage for older PCs

A compact flash to IDE adapter like this costs as little as $4 and adds flash storage cheaply to any PC that can use IDE.

Compact Flash, as it turns out, is based on the old parallel IDE standard. So it’s very easy to turn a Compact Flash card into an old-fashioned IDE drive. I messed with an adapter that does just that a couple of years ago. My IBM 5170 is using a $10 compact flash to IDE adapter with a 128MB compact flash card for storage. Small by modern standards, but it’s the biggest that system supported without a BIOS replacement. It was huge in the machine’s prime.

For maximum convenience, get one that has an ISA bracket so you can remove the card from the outside. They cost more than the $4 models but they make it easy to pop the card into a modern machine to copy files to it quickly.

Just be sure to keep the BIOS limits in mind with any older system. If you need to get around them, you can get an XT-IDE BIOS and install it in a network card. Set your hard drive type in the BIOS to none, and let the XT-IDE BIOS detect it. In spite of the name, XT IDE works on newer systems too.

But a full XT to IDE ISA adapter lets you use these solutions even in an XT system. I use one in my Tandy 1000. Some of them even have a compact flash slot built in, so there’s no need for the adapter.

SD to IDE

SD cards are more common. Not only are most people more likely to have them laying around; you can easily pick up a small one almost anywhere. Well, anywhere that there’s a drug store, or a discount store. You don’t have to buy them at consumer electronics stores. But I use the older ones from my parts bin that are no longer large enough to be practical to use in a camera.

You can get SD-IDE adapters as well. They cost more, at around $13, but the convenience is probably worth it. SD cards tend to be slower as well. That may not matter if you’re putting the device in something older than a Pentium II, but it’s something to keep in mind.

I use an SD to IDE adapter with an old 2 GB SD card in my 486. I find the performance more than acceptable. Ginormous cards can be a liability in pre-386 systems because of the time it takes to calculate the free space. So even though a 16 GB card costs a couple dollars and an XT to IDE BIOS supports it, you may be better off with a crusty old 2 or 4 GB card. Or better still with a 128 GB compact flash card.

Disadvantages to flash memory in older PCs

The disadvantages to using digital camera memory as a hard drive are multitasking and virtual memory. They aren’t very good at random writes, so they can get loaded down easily when more than one process is trying to access them. But most people who are looking to put flash memory in a PC that age aren’t looking to build a powerful workstation–they’re building the machine for a specific purpose. Like controlling lights, or playing specific old games that like a specific generation of hardware and operating system.

And they may very well be running DOS anyway, which doesn’t multitask or write to virtual memory.

The upside is that sequential reads are very fast, and flash memory is quiet, cool, and uses very little power.

So it’s possible to get it done inexpensively, without resorting to aged hard drives whose life expectancy may be questionable. And you may be able to repurpose an old card that’s no longer useful to you otherwise in order to do it.