gistfile1.txt

BR Main
choice:  .block 2
num:     .block 2
ans:     .block 2
msg:     .ascii "A - ADD \x00"
msg2:    .ascii "\nS - SUB \x00"
msg3:    .ascii "\nN - NEG \x00"
msg4:    .ascii "\nQ - Quit \x00"
ansmsg:  .ascii "Answer = \x00"
inputmsg:.ascii "\nInput Option: \x00"
inputnum:.ascii "Input number: \x00"


Main:    LDA 0,i
         STA ans,d
         STRO msg,d
         STRO msg2,d
         STRO msg3,d
         STRO msg4,d
do:      STRO inputmsg,d
         CHARI choice,d
         LDBYTEA choice,d
         CPA 'A',i
         BRNE elseif1
         STRO inputnum,d
         DECI num,d
         LDA ans,d
         ADDA num,d
         STA ans,d
         STRO ansmsg,d
         DECO ans,d
         BR do
elseif1: CPA 'S',i
         BRNE elseif2
         STRO inputnum,d
         DECI num,d
         LDA ans,d
         SUBA num,d
         STA ans,d
         STRO ansmsg,d
         DECO ans,d
         BR do
elseif2: CPA 'N',i
         BRNE while
         LDA ans,d
         NEGA
         STA ans,d
         STRO ansmsg,d
         DECO ans,d
         BR do
while:   CPA 'Q',i
         STOP
         .end

Interesting. Downloaded the simulator to try this and traced through the code. You should btw. do that too if you haven't done.

It took me some serious analysis to exclude away possible choices. I didn't have a manual so I did tests to verify the CHARI isn't affected by Accumulator or any of the status flags.

Figured out the CHARI only blocks when run after DECI. If I press N + enter, CHARI runs after CHARI, the second time will happily seem to go all the way down to QUIT.

Then I proceed to put CHARI -instructions one after another. When I keep typing characters pressing enter between them, every another CHARI doesn't wait for input. Next I made a program that prints out what CHARI received as a number.

Then I figured out what was the problem and fixed the program.

Later found the manual too..