// Store numbers in memory
// And keep current sum in B
// Sum sound and LED effects

// 1 RUN to start! 

// Init registers 

// A <- 0 

00 8 TIA 0 
01 0

// Index register: Y <- 0 

02 A TIY 0 
03 0

// A <-> B, we are using B for the sum, hence init with 0 as well! 

04 2 CH  A<->B, Y<->Z

// Now load both again 

05 8 TIA 0 
06 0

07 A TIY 0 
08 0

// Output Y on LEDs (NOT binary, 0 to 6) 

09 E CAL SETR 
0A 1 

// Keypad input loop 

0B 0 KAD
0C F JUMP 0B // Flag = 1 if no input, then loop 
0D 0
0E B

// Show input (in A) on HEX DISP 

0F 1 AO 

// Check if 0 -> exit 

10 C CIA 0, <> 0 -> Flag = 1 
11 0 

12 F JUMP 1C // If Flag (A <> 0), then jump 
13 1
14 C

// Else, input = 0 -> END program 

15 E Make error sound 
16 7

// Turn off HEX DISP 

17 E CAL 0
18 0 

// Endless loop 

19 F JUMP 19
1A 1
1B 9

// Else, input > 0 
// Store key (A) into memory cell M(Y) 

1C 4 AM  M(Y) <- A 

// Add to M(Y) to B, bring in sum in B 

1D 2 CH

1E 6 M+  A <- A + M(Y) 

1F 2 CH

// Delay to give time for keypad input display 

20 8 TIA 5 
21 5

22 E CAL E TIMR 
23 C 

// Incr. Y 

24 B AIY 1
25 1

// Y -> Z and incr. Y again 

26 2 CH 

27 B AIY 1
28 1

// DISP HEX current sum, as we currently have sum in A 

29 1 AO HEX DISP A

// Store sum back to B (keep it from being overwritten) 

2A 2 

// Next input 

2B F JUMP  09
2C 0
2D 9