My parents bought me an early Commodore 64 for Christmas in 1982 and I spent untold days typing in source code from Compute!'s Gazette which was the Commodore-dedicated companion to Compute!.
Their MLX system for entering assembly language programs with a checksum was an amazing way to enter programs from a magazine. I remember enlisting my sister to help me type in the programs and I told her, "Type the line of numbers here. If you type one wrong, it will tell you." She quickly retorted, "If it know what's write, why doesn't the computer type it in!?"
You talk about mind-numbing... A9 00 C0 A0 D4 01 03 05 0A
Apparently I did that too much because I can convert that to 6502 Assembly language in my head.
Yes! Compute!'s Gazette, that was it! Every month users would submit their homegrown works, like "I made a game that can display 16 sprites at once instead of 8 because of this clever IRQ trick" and it would contain the full assembly code, along with their checksum like you said. Compute!'s Gazette.
Actually got some submissions to COMPUTE!'s Gazette accepted in high school (though I also kept all my rejection letters). By then, though, they were technically COMPUTE Gazette Edition after the General Media buyout (yes, Bob "Penthouse" Guccione's outfit).
Their MLX system for entering assembly language programs with a checksum was an amazing way to enter programs from a magazine. I remember enlisting my sister to help me type in the programs and I told her, "Type the line of numbers here. If you type one wrong, it will tell you." She quickly retorted, "If it know what's write, why doesn't the computer type it in!?"
You talk about mind-numbing... A9 00 C0 A0 D4 01 03 05 0A
Apparently I did that too much because I can convert that to 6502 Assembly language in my head.