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Comment by IT4MD | Hacker News Reader

100% with you. I miss those times.. High-5 to a fellow 300bauder!

I built my own 300bps modem as a teenager, to connect to my C64. Tech was a lot more fun back in the day. It was exciting every year to see the speed of modems go up, and up, and up. 300 bps, 1200bps, and then when I got a 2400bps modem the C64 built-in serial code was too slow, I couldn't transfer files because there were so many dropped bits. So I wrote my own serial port code in assembly language and hacked it into my favorite terminal software (CCGMS) and that fixed the problem. I think by the time I got a 9600 baud modem I probably had an Amiga.

By the time you get to 2400bps you're starting to stress how fast the abysmal disk interface on the C64 could write data, you had better not hit too many seeks.

The 1541 drive can write at ~400 bytes per second, much faster than the 2400bps modem could deliver (240 bytes/s). And buffering was a thing back then. A simple ring buffer would suffice. I had no problems downloading at 2400bps after I fixed the serial code.

Faster, but not "much faster". Depending on where you were writing it could be as low as 300 bytes/second. You're starting to cut close to the margins, especially if the C=64 is having to also manage the modem communications at the same time. So yeah, doable but that's about the max you can expect out of the hardware. A 4800 baud modem would be right out.

The C64 doesn't control the disk drive directly, the 1541has its own CPU, about as powerful as the C64.

> A 4800 baud modem would be right out.

Not with a "Warp Speed" cartridge. It does write speeds on a stock C64/1541 up to 2900 Bytes per second. I'm pretty sure reading serial data faster than 2400bps is easily doable too.

https://www.obliterator918.com/the-warp-speed-cartridge-from...

Modern 1541 turbo, like Krills Transwarp, tops out just shy of 20KB/s on unmodified hardware https://csdb.dk/release/?id=214786 with steady 16KB/s in normal use https://www.obliterator918.com/benchmarking-transwarp-the-in... The trick is encoding files in special way to minimize drives CPU load.

CCGMS was the best.

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