A [relic][1] is "a surviving memorial of something past", which seems just about perfect for your purpose.  
To be sure, the most common association is with the relics of saints - fragments of the True Cross, or the bones of St. Mark - but relics are not necessarily religious. (Despite the similarity of spelling, "[relic][2]" and "[religion][3]" are derived from different Latin roots.)  

Historical artifacts, outmoded ideas, and even retired persons are often called "relics", so there's no reason your old laptop can't be one too.

  [1]: https://www.dictionary.com/browse/relic?s=t
  [2]: https://www.etymonline.com/word/relic
  [3]: https://www.etymonline.com/word/religion