Load tables with the program, not with INP

Say you want to look up the number of days in a month from a table of twelve.

You'd probably read the table in with INP when the program starts, using a little loop that rewrites its own INP to fill cells 40 to 51.

cell  contents  notes
 10      030    INP 30  cell 10: the month
 11      040    INP 40  cells 11-16: then read the table's 12 cards into cells 40-51
 12      111    CLA 11
 13      200    ADD 00
 14      611    STO 11
 15      731    SUB 31
 16      311    TAC 11
 17      130    CLA 30  cells 17-23: the days in month m are in cell 39 + m
 18      232    ADD 32
 19      620    STO 20
 20      100    CLA 00  CLA 39 + m, written by the cell before
 21      633    STO 33
 22      533    OUT 33
 23      900    HRS 00
 30      000
 31      052    INP 52
 32      139    CLA 39
 33      000

Step through the natural way in Cardigan

Instead, put the table on the program's own deck. The loader drops each entry into its cell on the way in, so your program doesn't need a fill loop at all. Loading isn't free, it costs three instructions a cell, but a fill loop pays that and more. One caveat: for a single value, a plain INP is still cheaper.

cell  contents  notes
 10      030    INP 30  cells 10-17: the days in month m are in cell 39 + m
 11      130    CLA 30
 12      231    ADD 31
 13      614    STO 14
 14      100    CLA 00  CLA 39 + m, written by the cell before
 15      632    STO 32
 16      532    OUT 32
 17      900    HRS 00
 30      000
 31      139    CLA 39
 32      000
 40      031    cells 40-51: the table, on the program's own deck
 41      028
 42      031
 43      030
 44      031
 45      030
 46      031
 47      031
 48      030
 49      031
 50      030
 51      031

Step through the CARDIAC way in Cardigan

Both print 30 for September. Counting the loading, reading the table in takes 18 cells and runs 140 instructions, and loading it with the program takes 23 cells and runs 83.

How the loader places a table, and how Cardigan's DATA cells get you there: programming basics.

From the tips in cardiac-code on GitHub. All the tips.