I was there in the 300 bps days with a Novation Apple Cat II and I never heard of such a thing. How did that work? Did you have non-standard modems on both ends?
If you had a pretty clean line, you could do 450 baud. Some BBSes had separate numbers for this speed. Sometimes it just worked with regular 300 lines.
Really? What standard allowed that? I'm only aware of 300 bps and 1200 bps. I'm not seeing anything in between those besides a V.22 standard for 600 bps I wasn't previously familiar with:
I also don't recall intermediate speeds. The modems at both ends would negotiate the highest standard speed they could. I must've owned a dozen dialup modems over the years starting with that Novation Apple Cat II (300 bps, 1200 bps half-duplex to another Apple Cat II) and just have no recollection of variable speeds like you're describing, and I spent a lot of time dialed into BBSes.
There's lots of knowledge from that era that didn't make it to the internet age. Not being listed on Wikipedia does not mean something didn't exist.
Maybe your modem just didn't support it. Or maybe it was one of the many mods people did to their modems.
I know that at least one of the modems I had (a combination of Commodore, Hayes, and Avatex modems) supported higher-than-usual baud rates out of the box. I can't say how exactly it worked, you just issued commands or the terminal program handled it.
Sure, it's possible it escaped both my memory/experience and what's on the Wikipedia. But I spent a ton of time online dialed into BBSes started around 1980, even running a small ISP in college. I have a CS degree. I took telecommunications courses in college. If there's something that escaped my knowledge, I'd love to know more about it.
To the very best of my knowledge, dial-up modems jumped from 300 bps to 1200 bps, and they exchanged data at whatever the highest speed they could negotiate. The Novation Apple Cat II modem was also pretty unique in that it supported 1200 bps half-duplex, but only to another Apple Cat II, and it also had the ability to detect and generate arbitrary tones. There were programs for it to play music and to use it as a voice modulator.
Which is all to say, I was pretty into this stuff.
So I'm really interested in any information about a modem that worked at intermediate speeds like 450 bps.
I searched textfiles.com but couldn't find anything there either.
FWIW, I had a very strong memory of a graphical BBS program that worked on the Apple II using hi-res mode and a dedicated client. I asked about it here over the years but was never able to find any confirmation it existed:
I was there in the 300 bps days with a Novation Apple Cat II and I never heard of such a thing. How did that work? Did you have non-standard modems on both ends?