The following is a summary of the support cards that go in the IBM 5100 main A1 board. These are “before cleaning” after 40 years!
NOTE: I don’t call these “expansion cards” since they don’t really expand the capability of the system. Rather, each of these cards is required in order to have a functional system.
| IBM 5100 SYSTEM SUPPORT CARDS | A1 BOARD SLOT |
 | SLOT C4 BASIC ROS (non-executable) 36KB |
 | SLOT E ROS Control |
 | SLOT F BASE I/O |
 | SLOT G Controller |
 | SLOT H2 BASIC, I/O, and Diagnostics Executable ROS |
 | SLOT J Display |
 | SLOT K2/K4 Read/Write Storage 8K and 8K |
Mixed Assortment (same cards as above)
