QBasic

And actually, QBasic 1.1 allows saving another byte, since it auto-adds a semicolon after ?TAB(i).

Yeah--near as I can tell, SPC does the same thing as SPACE$, except it's golfier and you can only use it in a PRINT statement.

i would have already if i wasn't super lazy >_>

Aaand yep, math can replace the IF statement: assign the condition k>=2^j to a variable (I used o, mnemonic "one bit") and then do s=s-o:k=k+o*2^j

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