The GE-Emerson IC600CB500 Series Six Arithmetic Control Module performs arithmetic and logical operations for the Series Six CPU. Four AM2903, bit-slice, integrated circuits contained on this module constitute a 16-bit microprocessor that works in conjunction with the Logic Control module to generate system control and timing signals. The Arithmetic Control module is linked to the Logic Control through a ribbon cable connector.
Visible through a lens on the faceplate are two LED indicators: One, marked "CHECK," remains lit to indicate that a self-test has been completed successfully once per I/O sweep; this LED also indicates that no abnormal conditions prevail in the CPU, such as system clock stopped, scan time longer than 300 milliseconds. The other LED, marked “RUN’ indicates that the CPU is performing execution sequences and is in the RUN mode. The LEDs operate only when the module is installed in a properly powered CPU rack.
