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Comment by ngc248 | Hacker News Reader

>>> You talk about mind-numbing... A9 00 C0 A0 D4 01 03 05 0A! for pages and pages and pages.

Man, seriously, can't even think what would happen if you made a typo and how you would debug it

There was some amount of "standardization" of checksum methods to help with debugging typos. For example, Nibble magazine used a couple of programs-- the one I remember using was Key Perfect-- that would scan your program in memory after you typed it in, and report a series of short hex checksums, one for each reasonably small chunk of program (bytes for machine language, or lines of BASIC code). The magazine article would include the correct Key Perfect checksums for the program; compare against the generated report, and a difference meant you "only" had to scan a dozen lines of source instead of hundreds.

As others have mentioned, the publishers had developed and distributed a checksum tool, written in BASIC, that you could type in from scratch as well. Although I think I copied mine from a friend who did subscribe to the monthly diskette version.

So you couldn't enter a line wrong, it would get flagged right away.

As far as debugging the whole thing, I think they just published a dump of the known-good copy they received with the user's submission. I think you had to provide two separate, working copies of your program along with the source code?

Worse, imagine going through all that, with no typos, and it still not working.

Friend and I paired up doing that once. Boy, I tell ya, you don’t have to tell us 4 times the code won’t work.

Oh, and “3rd times a charm” is a lie.

>Boy, I tell ya, you don’t have to tell us 4 times the code won’t work.

this might be the first time i've seen this, but love it

A lot of machine code listings had per-line checksums which could be checked with a small auxiliary program. PC Magazine had assembly source for its free utilities, alongside a BASIC program that would produce the utility from machine code encoded as hexadecimal numbers in DATA statements; the BASIC program also included checksums and would check the machine code as it ran.

i can remember what would happen. of course, it depends on where the bug was and what it was for. i remember the bits of hex being proceeded by the DATA keyword. in one instance, the DATA was for the audio, and it played a horrendous noise. as the multiple typos that were present were fixed, the audio went from horrendous to glitchy. some of the DATA was for the graphics, and they'd present as glitches as well.

a friend of mine and i "developed" a coding technique (we were 10 years old) where i would type in the initial load (i seemed to be a better/faster hunt&peck typist). after that, we'd switch. i'd read the DATA hex, and he'd follow along on the screen and make corrections. it wasn't until many years later before i realized that the coding technique wasn't an original something that we "developed".

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