IBM PCjr "sidecars" and software
The junior was designed to be a low cost system. There were several things that contributed to this end. First was a lack of hardware support in the base unit for many hardware features that were standard on the IBM PC. In order to support such features as a modem, hard disc, printer or RAM expansion, "sidecars" could be added to the system. The system seen here has two sidecars attached to it. On the far right there is a stack of five other sidecars. They are just a part of the display and are not connected to the system.
A second design feature that contributed to low cost was a cartridge slot. These cartridges could contain software like the BASIC ROM that was included in the PC but not in the jr. There is a cartridge leaning on the front of the system on the left of the picture. It would be inserted into a slot below the floppy drive.
Lots of software was available for the jr. We see here several 5-1/4 in floppy drives in a typical desk container.
