Double-spaced Listings On Commodore Printers

I have a Commodore 64 and a Commodore 1525E printer. There are many occasions while I'm debugging a new program when a double-spaced paper listing would provide a lot more room to make corrections and additions.

Is there a way to force the LIST command to double-space on the printer without modifying the program being listed? Perhaps Jim Butterfield could suggest a short machine language routine.

Stephen D. Eitelman

Yes, it is possible to command the printer to double-space during the LIST command. In fact, all Commodore printers and many other printers have this ability. You will also, of course, see double-spaced listings on your screen. With any Commodore printer, you can enter and run one of these short BASIC programs, which will POKE a machine language program into the cassette buffer to create double-spacing.

5 AD = PEEK (55) + PEEK (56) * 256–20
10 I = AD
15 POKE 55, AD AND 255 : POKE 56,AD/256
20 READ A : IF A = 256 THEN END
25 IF A = -1 THEN A = (AD + 11) AND 255
26 IF A = -2 THEN A = (AD + 11) /256
30 POKE I, A : I = I + 1 : GOTO 20
35 PRINT" {CLR} RUN WITH : {RED} SYS" AD
40 CLR
828 DATA 169, -1, 141, 38, 3
834 DATA 169, -2, 141, 39, 3
840 DATA 96, 201, 13, 208, 5
846 DATA 32, 122, 242, 169, 13
852 DATA 76, 122, 242, 256

5 PRINT" {CLR} RUN WITH SYS 679"
10 I = 679
20 READ A : IF A = 256 THEN END
30 POKE I, A : I = 1 + 1 : GOTO 20
679 DATA 169, 178, 141, 38, 3, 169, 2
687 DATA 141, 39, 3, 96, 201, 13, 208
695 DATA 5, 32, 202, 241, 169, 13, 76
703 DATA 202, 241, 256