This directory contains disk images for the H89 (and probably H8) series of computers by Heathkit and Zenith Data Systems. The images, when decompressed, have a common format: Sequential disk data and the 128 byte record following the last sector will contain an ASCII header describing the physical disk format. There is no meta-data in the disk image, only in the 128 byte record following the image.
The header uses a "postfix" notation of parameters, finishing with a linefeed character. Each parameter consists of a numeric ASCII string following by a single letter. This format may be used with the Virtual H89 computer or may be accessed with other tools and possibly copied onto diskettes or other physical media for use in real computers.
SASI images may be copied/loaded onto a CF card and used in the Z67-IDE(-Plus) adapters, although that exact procedure is TBD. SASI images have a "pre-boot" region (12 CP/M records) that includes a partition table and DPBs with mode bytes. The physical sector size is recorded in the DPB modes bytes, which is where the MMS driver looks for it. The DPBs use a logical disk geometry and are thus insulated from the physical disk geometry. The only reason the physical sector size is needed is to properly communicate with the adapter.
Image files names that end in ".xz" are XZ Compressed. Utilities to decompress should be readily available. WinZip is purported to include support for XZ compression.