Your question about Siemens S30810-Q2040-X1 IOCG

The IOCG (Input/Output Controller - Group) is used with the Hicom 390 systems and is a component of the group processor (GP) (DP/LTG). It contains the input/output control for the line trunk group (LTG) and the clock repeater.

The IOCG is used to transfer message traffic and start-up data between the GP of the LTG and the common control message buffer unit, via the message distributor (MD).

The clock repeater receives a reference frequency CKA (central clock A) of 2.048 MHz from the central clock generator. The CR must then generate and distribute the system clocks CKC# 8.192 MHz, CKB# 4.096 MHz, and CKA# 2.048 MHz in synchronism with the central CKA.

The reference frame mark bit FMB is used to generate the frame mark bit FMB#, which is used to synchronize various counters and flip-flops.

The front panel of the board contains a 7-segment display, 2 LEDs (RUN, CR), 2 keys (Reset, Monitor) and one V.24 interface.