Given the following test program that I wrote (GETC.MAC):
.title getc
.mcall .exit
TKS = 177560
TKB = 177562
;TPS = 177564
;TPB = 177566
begin:
inc TKS ;set the ASR read enable bit
getc:
tstb TKS ;is a character available?
bpl getc ;loop until there is
movb TKB,R0 ;put the character into register 0
.exit
.end begin
I would expect the console to wait until I typed a single character and
then for the program to exit. What is happening is that the program
appears to accept any number of characters and only ends when I type
CTRL-C twice.
Here are some questions that arise:
1. Is it reasonable to expect to be able to read directly from the ASR
Keyboard buffer while running RT-11 in SimH or does this somehow compete
with the running OS? (I can print characters using the ASR Punch Buffer
just fine)
2. Is there a flaw in the program? (Nevermind that it doesn't do
anything much with the character).
3. Is this a totally abnormal way to read a character?
4. What's up with needing to hit CTRL-C twice?
Answers to any of the above would be appreciated or if you have
something else, that's fine too.
Thanks,
Will
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