IBM 5406 System/3

On March 4, 2021 the Arlington (Massachusetts) Coal & Lumber Company donated an IBM 5406 Model B3 System/3, S/N 32379, including a 5444 Model 1 disk drive, S/N 48754, and a 5213 Model 2 printer, S/N 21627, and equipped with 12k bytes of core memory . This system was installed on Valentine's day in 1973 and was used to manage their inventory and billing.

The System/3 is the first member of IBM's Midrange Systems that were produced in Rochester Minnesota from July 30, 1969 to June 1985. The 5406 was introduced on October 28, 1970.

There is a WWW site dedicated to the IBM System/3 here: There are 42 System/3 machines known to exist.

Quite a bit of documentation for this machine has been scanned and is available here.

IBM 5406 System/3 Restoration blog.

This list describes all of the features that were included when the machine was first built.

The disk drive in the original order is a 5444 Model 1 with a 1.2MB fixed and 1.2MB removable storage. The disk controller is actually jumpered for a 5444 Model 2 with 2.4MB fixed and 2.4MB removable storage. Sometime in the machine's working life the disk capacity was upgraded. The 5444 Model 1 and Model 2 drives are physically the same, but the Model 1 is restricted to 1/2 of the full capacity.

Optional Features that are not installed on this machine:

  • Bisynchronous Communications Adapter: Allows this system to talk to a mainframe through a modem. BISYNC allows you to transfer files and reports between the two machines, as well as run jobs on the other machine.

  • Serial I/O Channel:</