Write a downloaded img file to compact flash

Thanks to the MiSTer project and a number of other retro computing initiatives, there are a number of DOS disc images floating around containing a bootable operating system and a compilation of software. While these are intended for use on devices like the MiSTer, there was no reason you can’t use them on regular hardware as well. It’s possible to write a downloaded img file to compact flash.

Here’s how I got a pre-configured image of 1981 to 1987 software written to a compact flash card and running on a Tandy 1000.

The hardware

First, you need suitable hardware to run it on. I used a Tandy 1000 EX with a 3-in-1 card that included a compact flash slot. Any vintage PC with an XT to IDE adapter or another suitable IDE interface will do.

Next, I purchased a suitable 512 MB compact flash card. These are readily available on eBay for less than $10. I also purchased a compact flash to USB adapter for my modern PC. This also cost less than $10.

Now it’s just a matter of getting an image and writing the image to the card.

I used this DOS Play it By Year image from archive.org, and I used a utility called HDD Raw Copy Tool. If you have a favorite utility, feel free to use that. I had this one on hand and can provide a full walkthrough with it.

Write an IMG to compact flash using HDD Raw Copy Tool

First, insert the compact flash card into the reader, and plug the reader into your PC if it’s not there already. If the compact flash card doesn’t show up in Windows explorer, make sure you have the card plugged in the right way. It May feel like the card is keyed so it only goes in one way, but it is possible to plug a compact flash card in upside down, and most readers do not tell you which way is up.

Next, open HDD Raw Copy Tool.

write img file to compact flash, step 1
Double click where HDD Raw Copy Tool says file to choose your source file.

Choosing the source may not be intuitive in this case. Double click on file and choose your downloaded disk image from the subsequent dialog box. But that’s the hardest part. Really.

write img file to compact flash, step 2
Choose your destination.

Next, it will ask for a destination device. Choose your compact flash card, which in my case shows up as a USB mass storage device. Make absolutely certain you triple and quadruple check the name of the device and the size. Utilities like HDD Raw Copy Tool will happily overwrite the local storage on your system. Pay close attention to megabytes and gigabytes. When you’re sure, click Continue.

write img file to compact flash, step 3
Click start to write the file, after triple and quadruple checking everything.

Click start and then let the file write to the compact flash card. In my case it wrote about 10 and a half megabytes per second, so it took a little less than a minute.

The image I downloaded contains a huge number of useful utilities, but we all have our preferred tools. The image has about eight megabytes free, which is enough room to copy a preferred mouse driver and anything else the image seems to lack.

With the image written, eject the compact flash reader from the system tray in Windows, pull the card, and insert the card in the reader in the Tandy 1000.

Booting the card

The image boots to a usable DOS 6.22 build. I found I needed to adapt the config.sys and autoexec.bat to my liking, as they assume expanded memory, which my Tandy doesn’t have. Not that I am complaining. Having a half gig of software on a bootable image in about a minute it is unbelievable.

I’ll gladly spend 30 minutes tweaking someone else’s set up to my liking rather than building it from scratch.

This trick works in reverse as well. If you built up your vintage PC from floppies or other media and want to back it up onto your modern PC, simply remove the media from your vintage PC, then use the utility to write from your compact flash or SD card to a file on your local PC. Now you can make changes to the original without fear and can easily revert any changes if needed. Or you can copy the media to use as a starting point for another machine.

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