A Newbie Writes...
Posted: June 15th, 2015, 2:46 pm
Hi All,
I took delivery of my Altair Clone about 3 weeks ago (thanks Mike) and am having a lot of fun just dabbling with it as a complete novice. I've done the exercises in the Altair Clone manual and am seeing what else I can mess around with.
I was looking at the following simple program to test the 2SIO with TeraTerm (courtesy of http://www.solivant.com/altair_bootload ... rs&pagen=1), which echoes out received input:
Out of idle curiosity, I got to thinking it should be possible to take the input from the sense switches instead of the terminal and output that to the terminal. IIRC I changed the 021 for 377 on the input instruction (one or both, can't remember and am working away so can't test just now) and tried it out. My guess was I would be able to set values in the sense switches and have the ascii equivalent show up in the terminal. It sort of worked, echoing characters based on the sense switch values, but it only seemed to output when A8 switch was set to 1.
Anyone care to explain to an absolute beginner why this should be, or (teach a man to fish) point me in the right direction as to an explanation?
Cheers,
Jim
I took delivery of my Altair Clone about 3 weeks ago (thanks Mike) and am having a lot of fun just dabbling with it as a complete novice. I've done the exercises in the Altair Clone manual and am seeing what else I can mess around with.
I was looking at the following simple program to test the 2SIO with TeraTerm (courtesy of http://www.solivant.com/altair_bootload ... rs&pagen=1), which echoes out received input:
- Code: Select all
000: 076 003 323 020 076 021 323 020
010: 333 020 017 322 010 000 333 021
020: 323 021 303 010 000
init: mvi A, 003 ; Reset the 2SIO port 1
out 020
mvi A, 021 ; Set port 1 to 8,2,n
out 020
loop: in 020 ; wait for a character to arrive
rrc
jnc loop
in 021 ; get the character
out 021 ; send it back out
jmp loop ; continue forever
Out of idle curiosity, I got to thinking it should be possible to take the input from the sense switches instead of the terminal and output that to the terminal. IIRC I changed the 021 for 377 on the input instruction (one or both, can't remember and am working away so can't test just now) and tried it out. My guess was I would be able to set values in the sense switches and have the ascii equivalent show up in the terminal. It sort of worked, echoing characters based on the sense switch values, but it only seemed to output when A8 switch was set to 1.
Anyone care to explain to an absolute beginner why this should be, or (teach a man to fish) point me in the right direction as to an explanation?
Cheers,
Jim