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In the 1980s we downloaded games from the radio

(newslttrs.com)
286 points spzb | 4 comments | 28 Mar 25 22:14 UTC | HN request time: 0.292s | source
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coreyh14444 ◴[31 Mar 25 10:49 UTC] No.43533429[source]▶
I definitely had cassette based games on the TRS-80, but most of the "wireless" transmission in my youth was via BASIC printed in the back of computer magazines. You had to type in the entire app yourself. I did this for basically every app they listed. Sometimes it was like tax prep software, but I didn't care, even though I was like 9 at the time. Yes, it took a very long time. Yes, you could easily introduce typos and bugs.
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mysterydip ◴[31 Mar 25 10:55 UTC] No.43533473[source]▶
Sometimes the typos were in the magazine itself, and you wouldn't figure out the problem with the code you triple-checked you typed in properly until the errata in next month's issue :)
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jonwinstanley ◴[31 Mar 25 13:56 UTC] No.43535117[source]▶
The compiler/interpreter couldn’t even tell you what line the error was on!

You’d just get a big error message for the whole program.

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aaronbaugher ◴[31 Mar 25 15:52 UTC] No.43536420[source]▶
After a while, magazines like Commodore Run and Compute started including a short program that would checksum each line as you entered it, so you could check that against a checksum in the magazine. Of course, you had to get that program typed in correctly first before you could use it to enter others.
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1. tantalor ◴[31 Mar 25 18:18 UTC] No.43538009[source]▶
I'm curious, can you say more about "as you entered it"?

Do you mean like, "for lines 1-20 the checksum should be 0xDEADBEEF"? This would let you find the error before finishing the program.

Or just at the end, it would checksum the whole thing?

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2. onre ◴[31 Mar 25 20:37 UTC] No.43539670[source]▶
I remember borrowing a book from the library, which had a type-in checksum program of this sort. It was done like was common for C=64 things of this kind - there's a BASIC FOR-loop iterating through a memory area, reading in bytes from DATA statements you've typed in and POKEing those bytes into memory, not completely unlike entering a program manually from the front-panel switches of an older computer.

So, after typing that in and probably SYSing (C=64 BASIC command for executing machine code from arbitrary memory location) to some address, it did print out a two-digit (eight-bit) hex checksum after every BASIC line I entered on the C=64 and the program listing in the book had the correct checksums for every line, so spotting errors was more or less instantaneous.

This stuff brings memories.

  FOR I=40960 TO 49152:POKE I,PEEK(I):NEXT I
  POKE 1,54
From top of my head; loop through the BASIC interpreter area, reading byte by byte with PEEK and POKEing those bytes back to the same addresses. Sounds nonsensical? Not so, because the C=64 does have full 64 kB of RAM, but some of it is overlapped by ROMs. What happens here is that you're reading from ROM but writes always go to RAM, so you're copying the BASIC interpreter from ROM to RAM. After that, the POKE statement turns off the ROM overlap and the interpreter is now run from RAM, so you can edit it live - and obviously cause all sorts of interesting crash situations.

It sure did help later with career in IT to have understood this kind of stuff at age of around ten.

3. rufus_foreman ◴[31 Mar 25 21:32 UTC] No.43540214[source]▶
A checksum for each line of code. COMPUTE! magazine used one, the article introducing it and explaining how to use it is at https://archive.org/details/1983-10-computegazette/page/n49/....

The code listings had a comment (rem) at the end of each line with a checksum number, when you used the checksum program it would display a checksum at the top of the screen that would match if you entered the line correctly.

An example page of code with checksums is at https://archive.org/details/1983-10-computegazette/page/146/....

A life changing event for those of us entering code from magazine listings in the early '80s.

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4. tantalor ◴[01 Apr 25 16:22 UTC] No.43548628[source]▶
That's awesome. Thanks!