Giving the C64 a WiFi Modem

[BigEd]

I like that 31 baud is about typing rate - a human-scaled modulation scheme. The Varicode variable-length coding is clever too, but means you'd need some little state machine thingy as well as the analogue demodulator.

[GARTHWILSON]

Interesting. https://en.wikipedia.org/wiki/PSK31
I'm a radio amateur but I have been inactive for 32 years (although I keep my license up). I have looked with only mild interest at what's happening in the world of amateur radio today, and I do see a lot of digital stuff. I definitely don't want my radio equipment dependent on a PC, but I think I could implement PSK31 on a 6502/'816 computer. I could also however make a filter that's sharp enough to do Morse code with only 20Hz bandwidth or less, similar to PSK31's apparent bandwidth. This allows communicating on extremely low power. The greatest distance I ever did on low power was when I was in Hawaii in 1981 and contacted someone in the middle East, nearly on the other side of the world, with about 2 watts. The antenna was just a random-length wire, supported from trees by insulators, tuned with a good little transmatch, no ground, no balun, etc.. More normal though was to be talking with someone in New Zealand, Japan, or the continental US from there.

[BigEd]

Extraordinary!

Thinking about it, if the analogue front end just output a single voltage for phase, or a pair of voltages, that would be a very low bandwidth signal for a 6502 to work on. It could probably even be handled as a background task.

[White Flame]

KC9UDX wrote:

I wonder what one does with a Wi-Fi modem on a C64. Presumably it works on the VIC-20 as well. It could probably be made to work with the PET, or anything else with a VIA or two.

There are telnet BBSes out there which support PETSCII, and I presume there are also ftp/wget style file transfer programs available for it. The Portland C= group runs a c64 website which I think caters to platforms like this, including chat and files and such.

The setup is basically a modern equivalent of RS232; every machine can easily talk through it (even though there's a ton of complexity hidden underneath) so you can start talking to your PCs which no longer have easy-access homebrew hardware communications ports.

BigEd wrote:

I like that 31 baud is about typing rate - a human-scaled modulation scheme.

You must be a very slow typist.

[KC9UDX]

If you were to get back into amateur radio after 32 years, and didn't take serious interest in PSK-31, JT-65, and all the trendy digital voice nonsense, I think you'd be very disappointed; as much as I hate to say it.

Most amateurs seem to be perfectly content connecting a black box to an overcomplicated computer to communicate. It's even popular to "work the world" whilst you're off somewhere else and your computer does all the work. I find it all disturbing, but I guess I'm in the minority, too.

I have hardware and software to do keyboard Morse, RTTY, Olivia, SSTV, and PACTOR modes with my C64 and 50 year old radio gear, but I don't have the time to play, and if I did, digital communication just isn't high on the priority list.

[Aslak3]

OT.

I just wanted to thank everyone for this place. I don't know anywhere else like this forum. I've been hanging around here for about 3 years now, and though I don't actually use the processor that this forum is mainly about in my projects (please don't hate me - if it helps at all I do use the 6522 in my micros and think it's awesome).... I love this place and the community here. This thread has really brightened my day. In a world where everyone blathers on about Linux, Auduinos, developments environments that require GB of RAM just to start up, impenetrable abstraction layers and all that... It's great to come here and see people who share the same views about what matters in computing, and engineering in general: understandability, simplicity, grace, beauty etc.

I will get back to my assembly coding now.

[GARTHWILSON]

Quote:

If you were to get back into amateur radio after 32 years, and didn't take serious interest in PSK-31, JT-65, and all the trendy digital voice nonsense, I think you'd be very disappointed; as much as I hate to say it.

The only thing I did was QRP CW. (For non-hams, that basically means very low-power continuous-wave telegraphy.) On the voice bands, I got tired of everyone talking about things like how many pairs of shoes their wife had. The more-serious people were on CW, ready to talk technical (although I can't deny having talked about music performance one time). I could also come closer to understanding the entire radio when voice was not involved (similar to why I like the 6502/816).

Morse is a lot more friendly than inexperienced people might think, not sterile or faceless. As I tuned across a band, I could immediately recognize the "voice" (fist) of various people I had talked to before, if they used a straight key instead of a keyer. I could say, "There's ol' Harry down in New Zealand...There's Bob up in Santa Maria...<etc.>" And you do get inflections and so on. It also goes faster than the WPM number suggests, because of all the abbreviating, and when you're going more slowly, you have time to think of how to say something in fewer words. I had no less fun talking to someone 150 miles away than someone 5,000 miles away, as long as we could ragchew. I didn't really like talking to the Japanese because they just wanted to get my QSL card and get off and get to the next person. I understand they had to prove so many contacts to upgrade their license. I enjoyed the code, and I enjoyed the challenge and success of communicating with simple equipment and low power. I don't think it would be as fun with a big black-box rig and 1kw linear and a 60' tower and beam antenna.

I know there are repeaters now that go through the internet so you could use a 2m or 70cm walkie-talkie to talk to someone thousands of miles away; but part of the value I see in amateur radio is to meet the need when the phone system or internet go down, whether locally or on a larger scale, for whatever reason that caused the emergency.

One friend has tried to get me interested in VLF, like 170kHz. I thought it was funny that I could do SDR on a 6502 and use an audio amplifier IC for the output! It would be fun to see how low a power you can succeed with if the receiver's passband was only about 10Hz wide! For that matter though, you could do a very small HF transceiver with a collapsible antenna, since with VLF you're limited to 50 feet. That would be kind of like a 3-foot-long antenna on 80M.

[White Flame]

GARTHWILSON wrote:

And you do get inflections and so on.

I read that as "infections" at first, imagining a morse code operator's version of Nintendo Thumb.

[BigEd]

Aslak3 wrote:

I just wanted to thank everyone for this place.

Lovely note aslak3! I feel the same.

White Flame wrote:

BigEd wrote:

I like that 31 baud is about typing rate - a human-scaled modulation scheme.

You must be a very slow typist. ;)

I seem to be typing at about 31.7 bits per second, according to http://typing-speed-test.aoeu.eu/ - and it felt quite fast!

[White Flame]

How did you calculate that, CPM / 60(sec/min) * 8(bit/char)? So I guess 31.7 bps would be 237.75cpm, or 47.55wpm. 60wpm is a common minimum rate for typing-oriented jobs, and is probably a reasonable threshold for "fast".

Because of people I've worked with, I tend to assume that technical computer users, especially long-term ones, are fast typists. I was just going off the fact that it wasn't uncommon for typing to outrun modems back in the day, so 31 baud seems astronomically constrained. However, that could also be due to other latency factors than line speed. (I ran that linked test above one time, got 551cpm, 110wpm)

[BigEd]

I went with 10 bits per char. I just tested again, got 304cpm, 61wpm, so thats 3040bits/60sec or 50bps. So that was a bit quicker, but on a different keyboard. I'm nowhere near accurate enough to have a typing job, but I've generally been paid to solve problems - which happens to involve typing. (Normally a lot of my keystrokes are backspace...)

[Dr Jefyll]

White Flame wrote:

I tend to assume that technical computer users, especially long-term ones, are fast typists.

Hah -- I wish! But I'm with Ed. A lot of my keystrokes are backspace.

[KC9UDX]

You think infections are bad? How about fascist long term technical computer users?

I don't think it's fair to assume 10 or even 8 bits when evaluating varicode (varicose?).

[BigEd]

You're right about varicode's bit density - but I've always found 10 a nice easy number for dividing by!

[KC9UDX]

Because you, like me, and everyone else, are unfortunately rigidly accustomed to base 10 maths.