Society of Eight-Bit Heathkit Computerists

A web site dedicated to preserving the Heathkit 8 bit computers


The H8D image format is the standard 10 sector 40 track disk format for Heathkit H-8 and H-89 computers. This image format stores the disk tracks as groups of 256 byte sectors starting with track 0 and ending with track 39. Track 0 occupies the first 2560 bytes (10 sectors, 256 bytes per sector) followed by track 1 and so on. There are a couple ways to use these disk images with your Heathkit computer:

First, you can find and buy an SVD. It is an electronic floppy drive that works with several different computer models including the Heathkit H-8 and H-89. You plug the SVD into the floppy cable as if it were a floppy disk drive and upload the disk images to it. The computer then thinks it is talking to a floppy drive with a Heathkit disk inside.

Second, you can use Dwight Elvey's H89LDR program and my H8D Utility to transfer disk images back and forth to a real floppy disk. Do this by connecting your Heathkit computer to a PC using a serial cable and then use the software to send/receive disk images. This method will work with a real floppy disk inserted into your computer's disk drive.

Third, you can use H8DIMGR running on a real Heathkit computer and my H8D Utility V1.51 or later to transfer hard sector disk images of any size to and from a floppy disk in your Heathkit computer via a serial port.

For high density hard sector disks the format is as follows: track 0 side 1 2560 bytes, track 0 side 2
2560 bytes, track 1 side 1 2560 bytes, track 1 side 2 2560 bytes, etc. This applies to both HDOS and CPM 200K and 400K disks.

December 27, 2013

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