Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

In the 1980s we downloaded games from the radio

newslttrs.com

Post reply on HN
Print view View original

141–150 of 153 posts

Re: In the 1980s we downloaded games from the radio

#141

Post by omoikane »

unsui wrote: post #137
aaronbaugher wrote: post #101

Earlier quoted context omitted.

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.

My favorite was the "TYPO II" ("Type Your Program Once") application, which was part of every Antic! Magazine program listing: https://www.atarimagazines.com/v3n9/TYPOII.html https://www.atarimagazines.com/antic/ This was wrapper around the BASIC interpreter that printed out a 2-character checksum of each entered code line. The magazine printing also had an associated 2-character checksum for each line. Your job: mak…

I took a look at the listing[1] and looks like it contains unprintable characters, maybe they were ASCII art of some sort?

The checksum algorithm is fairly simple: line 32150 sums the products of all character positions and character codes, and lines 32160-32180 does a modulus to convert them to printable characters. The multiply-by-position bit is clever because it allows the checksum to flag transposed characters. ISBN-10 uses a similar scheme[2].

[1] https://www.atarimagazines.com/software/displayfile.php?file...

[2] https://en.wikipedia.org/wiki/ISBN#ISBN-10_check_digits

Re: In the 1980s we downloaded games from the radio

#142

Post by unsui »

omoikane wrote: post #141
unsui wrote: post #137

Earlier quoted context omitted.

My favorite was the "TYPO II" ("Type Your Program Once") application, which was part of every Antic! Magazine program listing: https://www.atarimagazines.com/v3n9/TYPOII.html https://www.atarimagazines.com/antic/ This was wrapper around the BASIC interpreter that printed out a 2-character checksum of each entered code line. The magazine printing also had an associated 2-character checksum for each line. Your job: mak…

I took a look at the listing[1] and looks like it contains unprintable characters, maybe they were ASCII art of some sort? The checksum algorithm is fairly simple: line 32150 sums the products of all character positions and character codes, and lines 32160-32180 does a modulus to convert them to printable characters. The multiply-by-position bit is clever because it allows the checksum to flag transposed characters.…

I naturally went down a rabbit hole to see if I could find why those characters weren't printing properly.

https://www.atarimania.com/mags/pdf/Antic_Vol_7_No_4.pdf

On p. 31, you can see the intended characters.

I now remember that Atari actually had their own variant of ASCII, called ATASCII:

https://en.wikipedia.org/wiki/ATASCII

Atari 8-bits were actually really cool computers, in that they let you do things like redefine character sets entirely (to create custom character sets to effectively create tile-based displays), play with display-list interrupts, etc.

Re: In the 1980s we downloaded games from the radio

#143

Post by crazygringo »

nunez wrote: post #77

Insane that there are people denying that this happened. I wasn't born during this period, but being able to download stuff off of terrestrial radio is completely believable. What do people think Wi-Fi or cellular networks are???

I was skeptical until I saw information confirming it.

It's not obvious that the frequency range used by computers recording on audiocassette would fit into that used by AM or FM radio transmission and reception equipment.

In other words, it's obvious that it would be possible on equipment specifically designed for it.

But I'm quite surprised that it worked without it (presumably) having been designed for. Or maybe they did pick a frequency ceiling compatible with commercial radio intentionally?

Re: In the 1980s we downloaded games from the radio

#144

Post by omoikane »

unsui wrote: post #142
omoikane wrote: post #141

Earlier quoted context omitted.

I took a look at the listing[1] and looks like it contains unprintable characters, maybe they were ASCII art of some sort? The checksum algorithm is fairly simple: line 32150 sums the products of all character positions and character codes, and lines 32160-32180 does a modulus to convert them to printable characters. The multiply-by-position bit is clever because it allows the checksum to flag transposed characters.…

I naturally went down a rabbit hole to see if I could find why those characters weren't printing properly. https://www.atarimania.com/mags/pdf/Antic_Vol_7_No_4.pdf On p. 31, you can see the intended characters. I now remember that Atari actually had their own variant of ASCII, called ATASCII: https://en.wikipedia.org/wiki/ATASCII Atari 8-bits were actually really cool computers, in that they let you do things like re…

Nice find :)

I guess Atari character set has enough overlap with ASCII, so I could get the checksum to match:

    sum = 0
    "32000 REM TYPO II BY ANDY BARTON".codepoints.each_with_index{|c, i| sum += (i + 1) * c }
    print ((sum % 676) / 26 + 65).chr, (sum % 26 + 65).chr, "\n"
(Ruby code, outputs "WB")

Re: In the 1980s we downloaded games from the radio

#145

Post by LennyHenrysNuts »

coreyh14444 wrote: post #11

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…

I had the Dragon 32, which is the only Welsh microcomputer ever made (I think). Fantastic machine.

Re: In the 1980s we downloaded games from the radio

#146

Post by fabiopjve »

I did that in Brasil in the late 80s! There was a show on the radio that every sunday afternoon they would broadcast computer programs! The problem is that I had a coco2 clone and most programs were for Spectrum or MSX (the more common machines in Brasil back then). Needless to say, any noise on the radio would damage the recording and the transmitter was very far from me so usually there was noise... :(

Re: In the 1980s we downloaded games from the radio

#147

Post by flohofwoe »

crazygringo wrote: post #143
nunez wrote: post #77

Insane that there are people denying that this happened. I wasn't born during this period, but being able to download stuff off of terrestrial radio is completely believable. What do people think Wi-Fi or cellular networks are???

I was skeptical until I saw information confirming it. It's not obvious that the frequency range used by computers recording on audiocassette would fit into that used by AM or FM radio transmission and reception equipment. In other words, it's obvious that it would be possible on equipment specifically designed for it. But I'm quite surprised that it worked without it (presumably) having been designed for. Or maybe t…

The cassette loading/saving on home computers had to be extremely failure tolerant so that it would work with low quality tapes and shitty recorders. I guess as a side effect this failure tolerance also made it work over radio.

Re: In the 1980s we downloaded games from the radio

#148

Post by card_zero »

coreyh14444 wrote: post #11

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…

"App"!?

https://archive.org/details/TRS-80_Microcomputer_News_Volume...

Re: In the 1980s we downloaded games from the radio

#149

Post by PeterStuer »

coreyh14444 wrote: post #11

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…

For Speccies the added debuff was typing over the poorly scanned rolls of lowrez thermal printed code. The Spectrum's ecosystem's thermal printer's output was barely legible straight of the press, let alone as a second generation copy.

https://www.youtube.com/watch?v=CnY_ra-cHM0

Re: In the 1980s we downloaded games from the radio

#150

Post by tantalor »

rufus_foreman wrote: post #134
tantalor wrote: post #117

Earlier quoted context omitted.

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?

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 e…

That's awesome. Thanks!
Post reply on HN