.tap image of the University of Utah V4 Unix tape read 2025-12-19
at The Computer History Museum.

The read had two bad blocks, which have been repaired in the
uploaded image

It is the Unix distribution tape format documented in the v4 docs

75 blocks of bootloader, includes a tp(1) archive with stuff like
mboot. Then 4872 blocks of an RK05 image, for which the first 4000
blocks is a UNIX fs containing the OS

Last 872 blocks happen to be slack data from an overwritten fs.