# Introduction Unix v4 is one of the oldest operating systems in the world, and its recovery is an important discovery for historians of technology. The tape from which it was recovered contained only 12 megabytes of data, but due to its historical and technological significance, the university decided to preserve it. The recovery of the only known copy of Unix v4 is an important discovery that opens up new avenues of research into the past of programming. # How was it recovered? The recovery of the only known copy of Unix v4 was a complex and delicate operation. The tape from which it was recovered contained data in a format incompatible with modern systems, so it needed to be carefully decrypted and reproduced. The team of researchers used a combination of advanced techniques to recover the only known copy of Unix v4. The procedure was carried out in a way that minimized the risk of damaging the data and ensured their integrity.