Why is the unpacked size of memtest so big?

[Symtax]

The zip for usb memtest is 11mb so why is unzipped memtest.img a gigabyte? also is there any real difference between using that, the smaller cd version, or the SMALLLLLer floppy version?
Im going to be putting it on ventoy anyway so flashing isnt an issue

[David (PassMark)]

MemTest86 is shipped as a disk image. So to "install" it you copy the entire disk image to a USB drive.
The disk image contains boot sector, partition table, disk partitions and the actual software. Boot sector is required to make the USB drive bootable and it isn't something that can be setup with a normal file copy.

The disk image zips up so tight because one of the partitions is mostly zeros. A long string of zeros compresses very well. The empty partition is required for the (optional) DMA test, test #14. The software will still run with it's special partitions missing, but you won't be able to run Test #14.

We no longer support CD or Floppy disk installs. But if you are testing very old hardware with a floppy drive it might make sense to use a very old release (V4.3).