DEC-10-HDKB-D DK10 Real Time Clock Maintenance Manual Jul73

This document is the Maintenance Manual for the Digital Equipment Corporation (DEC) DK10 Real Time Clock, an option designed for the DECsystem-10 computer.

The DK10 is an accurate, high-speed timer that functions as a combination interval timer, Non-PI in-progress timer, and a time-of-day clock. It features an internal 100-kHz ±0.01% crystal clock but can also utilize an external clock up to 400 kHz. It includes a frequency counter (clock register) and an interval register, generating a program interrupt whenever a comparison indicates their contents are equal. The clock is designed with synchronization to prevent missed pulses during reads and incorporates power loss protection to clear registers and prevent false data. Two device codes are available to support separate Executive and User mode timing applications.

The manual details four modes of operation:

1. Interval Clock: Counts predefined time blocks and generates interrupt requests.
2. Time-of-Day Clock: A software-implemented clock that accumulates time based on interval interrupts.
3. Non-PI In Progress Timer: Accumulates total time when the PDP-10 is not servicing or requesting interrupts.
4. Diagnostic Mode: Allows for testing the DK10's functionality and its PDP-10 I/O Bus connections.

It provides comprehensive information on the PDP-10 instructions (CONO, CONI, DATAO, DATAI) used to control and retrieve data from the DK10, its I/O Bus interface, and the functions of its indicator/control panel, which includes various status indicators and a clock source switch.

Crucially for maintenance, the document covers installation procedures, specific DK10 adjustments, marginal check specifications, and an introduction to DEC logic symbols necessary for understanding the extensive engineering drawings. These drawings include flow diagrams, clock counter schematics, I/O bus interface details, timing control logic, and power wiring.