CROS

Capacitor Read Only Storage

Note: ROS [Read Only Storage] is a generic term within the System/360 family. It is implemented differently (in terms of physical hardware) in different models. In the Model 65 - and several other models - tiny capacitors are used to represent the bits; 1s or 0s. This implementation is called CROS [Capacitor ROS]. On this page, as in the IBM documentation, the terms ROS and CROS are used interchangeably depending on the context.

Below is an illustration of the differences in ROS field (micro-order) structure between the standard and FAA Model 65s. It can be seen that 'spare' bits in the standard Model 65 have been allocated new functions in the FAA Model 65. It is significant to note that nothing has been taken away from the standard machine's ROS, functions have just been added.