KW11-P Programmable Real-Time Clock

The KW11-P Programmable Real-Time Clock is a UNIBUS device option which can either provide interval counting, or produce either single or repeated interrupts at a programmed rate (at a multiple of the base rate). Four different base clock rates are available:

• 100 KHz
• 10 KHz
• line rate from the AC power provided to the power supply
• external

The programming interface is fairly simple; there are three registers:

• control/status
• count set
• counter

The counter register can be set to count up or down, governed by the selected rate; an interrupt can be triggered when it reaches 0 (on overflow or underflow). It can then optionally be automatically reloaded from the count set register.

Implementation

Physically, the KW11-P is an quad-height board (M7228), which plugs into a SPC slot in a backplane.

Control and Status Register (CSR)

ERR	Unused							DONE	INTENB	FIX	UP/DN	MODE	RATE		RUN
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

• ERR - Overflow/underflow before previous interrupt completed
• DONE - Set on overflow/underflow (causes an interrupt when that happens, if the INTENB bit is set)
• INTENB - Interrupt enable
• FIX - Diagnostic count
• MODE - Count up/down
• MODE - Single/repeat interrupt
• RATE
  • 00 - 100 KHz
  • 01 - 10 KHz
  • 10 - line
  • 11 - external

All bits are read/write, except FIX (write-only), and DONE and ERR (read-only).

External links

• KW11-P programmable real-time clock manual (DEC-11-HPWB-D)
• KW11-P programmable real-time clock engineering drawings