It came to light because of publicity surrounding an effort to rebuild the computer.
The part has now been donated to the rebuild project and will be incorporated into the finished machine.
Edsac, the Electronic Delay Storage Automatic Calculator, ran its first programs in May 1949 and through its working life aided many scientists by analysing data generated by many different experiments.
Before now, it had not been known what happened to the parts of Edsac after it was decommissioned and dismantled in the 1950s.
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It now appears that at the end of Edsac's life it was sold off in an auction but it is not known who bought all the parts, the BBC reported.
"Details of the 'auction' are unclear, but there is a possibility that other parts of the original Edsac still exist and could even be in the Cambridge area stored away in lofts, garden sheds and garages," Herbert said.
He got it from a Cambridge scientist called Dr Robert Clarke in 1969, who had bought several Edsac pieces in the auction intending to turn them into bookshelves.
Little contacted the Edsac reconstruction team after reading about the project online, the report said.
The Chassis is designed to hold 28 of the 3,000 valves that formed the main computational elements of Edsac.
The 12 vertical racks of Edsac held up to 14 individual chassis on to which the valves were fixed.
Work is now under way to see how much of it can be incorporated into the reconstructed Edsac.
The reconstruction of Edsac is set to be completed by the end of the year.