RT-11 idle light pattern

[Paul Koning]

It's been a standard feature of RT-11 FB since it first came out (in V2).  You need to set the select switch to display the "Display" register (unlike most other OS idle patterns which rely on the data path display showing R0 when at a WAIT instruction.

Here's what it looked like in V2.0 rmonfb.mac:

; "A SOURCE OF INNOCENT MERRIMENT!"
;	- W.S. GILBERT, "MIKADO"
; "DID NOTHING IN PARTICULAR, AND DID IT VERY WELL"
;	- W.S. GILBERT, "IOLANTHE"
; "TO BE IDLE IS THE ULTIMATE PURPOSE OF THE BUSY"
;	- SAMUEL JOHNSON, "THE IDLER"

10$:	DEC	(PC)+		;THE RT-11 LIGHTS ROUTINE!
20$:	1
	BNE	14$		;NOT TOO OFTEN
	ADD	#512.,20$	;RESET COUNT, CLEAR CARRY
16$:	ROL	13$		;JUGGLE THE LIGHTS
	BNE	11$		;NOT CLEAR YET
	COM	13$		;TURN ON LIGHTS, SET CARRY
11$:	BCC	12$		;NOTHING FELL OFF, KEEP MOVING
	ADD	#100,16$	;REVERSE DIRECTION
	BIC	#200,16$	;ROL/ROR FLIP
12$:	MOV	(PC)+,@(PC)+	;PUT IN LIGHTS
13$:	.WORD	0,SR
14$:	MOVB	#MXJNUM/2+200,INTACT ;DO A COMPLETE SCAN
EXUSLK:	BR	EXUSER		;BACK INTO LOOKFOR LOOP

	paul

> On Dec 27, 2017, at 11:03 AM, william degnan via cctalk <cctalk at classiccmp.org> wrote:
> 
> Do you have an octal or asm listing for the part of the code with the
> migrating bar effect?   This would be a good practice / test for me to try
> on my RT 11 system.  Merry Christmas
> Bill