[HECnet] Speaking of IDLE

[Steve Davidson]

RT-11 is "famous" for self-modifying code.   That fact makes it so much
fun to debug when you have a real-time bug.   Been there... Done that...

-Steve

-----Original Message-----
From: owner-hecnet at Update.UU.SE 
[mailto:owner-hecnet at Update.UU.SE] On Behalf Of Johnny Billquist
Sent: Monday, June 04, 2012 22:52
To: hecnet at Update.UU.SE
Subject: Re: [HECnet] Speaking of IDLE

On 2012-06-05 04:44, Johnny Billquist wrote:
On 2012-06-05 03:24, Steve Davidson wrote:
Paul,

I think that depends on whether or not the idle loop 
pattern (for the 
console light display) is being used. The lights pattern most 
certainly makes use of the WAIT instruction. The SJ monitor is a 
completely different beast than FB and friends - no 
question about it!

Well, there are more ways to spin a cat... Or spin the 
lights in this 
case. WAIT is one way to show something on the front panel. Loading 
the display register is another.
RT-11 is in fact using the Switch Register at 177570 to 
display things 
on the front panel.
Look at RMONFB.MAC, around line 4800, to see the code.
(Every time I read the RT-11 sources, I feel a little dirty... No 
offense meant for the RT-11 fans around here or anywhere.)

It's all conditionalized on LIGH$T, and there is not even 
the option 
if you are running the SJ monitor...

Aw, heck. I might as well post the code, since isn't that long...

====
3$:
.IF NE   LIGH$T
  .ROM     DEC         LITECT,VALUE=1
                BNE         8$
                ADD         #512.,LITECT
4$:         ROL         7$
                BNE         5$
                COM         7$
5$:         BCC         6$
                ADD         #100,4$
                BIC         #200,4$
6$:         BIT         #LIGHT$,CONFG2
                BEQ         8$
                MOV         (PC)+,@(PC)+
7$:           .WORD   0,SR
.ENDC
8$:
..NULJ::
====

(And yes, SR is defined as 177570)

(And maybe you understand why I feel dirty when reading RT-11 
after this fine example of code... It's cut-and-pasted right 
from the source, it really looks just like this.)

	Johnny

-- 
Johnny Billquist                                   || "I'm on a bus
                                                                    ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
pdp is alive!                                         ||   tryin' to stay hip" - B. Idol