Two hours if you skip some galleries and many more if you want to read all the descriptions, watch all the videos, etc I'd recommend skipping some galleries if there are topics that you're more interested in than others
As with many museums, you could do a whirlwind visit in a couple hours or less, or spend an entire day or two exploring and reading, watching and listening to content. There are so many stories and artifacts to see! I recommend trying to align your visit with the timing of a live demo on Wednesdays or Saturdays (IBM 1401 system both of those days, or RAMAC or PDP-1 on some days - check website or call to confirm timing). The volunteers are incredible and really help to bring tech history and people to life. There are also tours at noon and 2pm led by volunteers that are great and help to highlight key artifacts, people and stories! I typically spend 2-4 hours during a visit.
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