And it was an "IBM 1602" although pretty obviously based very closely on the actual 1620.
The real world 1620 was a 50s era RTL scientific computer (IBM used to separate math processors from business processors, until the famous "360" that did everything pretty well). This used the SMS style hardware cards that everything IBM made used until the 360-era SLT cards. Each SMS card holds enough circuits to be roughly one 7400 series TTL chip.
He also has another series which he just finished that is very good as well about a family with the ability to step between diffrent timelines that's an interesting deconstruction of the trope.
While it starts as starts as a fantasy series, it eventually comes out their magic abilities are remnants of advanced nanotech from an interdimensional empire. Apparently a publisher he didn't like working with had the rights to his next Scifi series, so he had to start it as fantasy to get around the contract.
