There are thousands of slides in these boxes.
The old slide scanner has been out of commission for years, a victim of changing technology. The old SCSI interface is not supported on modern computers. I have often considered replacing it, but for whatever reason the idea has been delayed until now.
One of the better slide scanners available is the Plustek 7600i. I stumbled across a listing for rebuilt units on eBay, direct from the manufacturer. $245 with shipping was a great deal, one I could not resist.