I came across the following more recent discussion: 2022-05-05 Bit banging on a Tandy CoCo1 - Wikistix <https://www.stix.id.au/wiki/2022-05-05_Bit_banging_on_a_Tandy_CoCo1>
And it reminded me of some of my own past exploration into systems that did RS232 without an UART. One example is the NEC PC-8001 (system from about 1979). I recall having trouble getting it past 600 baud for some reason. Another example is the Color Computer 3. UltimateTerm 2.4 from 1987 could bit-bang reliably 9600 baud (also Twilight Term from 1996). The CoCo3 had a higher speed CPU option than its original. "bit banging" (imo) is the host system doing the work of producing the start/stop bits on its own. Which seems to be a "lost art" and why I've wondered if anyone has tried bit-banging on a modern-day 3GHz system - but bit-bang onto what? They took away our serial and parallel ports, like talking directly to a pin is now taboo (literally a security risk, as some networks lock out CD drives and USB also - "no information out" policies). With the UART assist of the RS232Pak cartridge, a CoCo3 managed 115200 baud using a very optimized NetMate terminal written in 2021. That's with the 6551 ACIA doing the serializing work (but I don't think it has any FIFO at all). I've been curious how much faster Interlink/Laplink/FastLynx really was across a parallel cable (I've yet to find reliable bytes-per-second rate info on those). On modernPC to modernPC I really was able to achieve 45KBps (bytes per second) on a 460Kbps serial connection (USB/serial adapters; ones with 128 byte FIFO) using regular ZModem protocol. There are "laplink-style-USB" things, but I'm still curious if we did USB/parallel adapters and a classic laplink cable on two modern PCs, could it surpass the 45KBps serial connection? Still a relic approach, as modern day WiFi+samba should be faster. But where is any modern-make software to even try? -Steve On Fri, Jan 31, 2025 at 2:13 PM Paul Koning via cctalk < cctalk@classiccmp.org> wrote: > > > > On Jan 31, 2025, at 2:18 PM, Wayne S via cctalk <cctalk@classiccmp.org> > wrote: > > > > Steve, remember that digital electronics ( I.E. integrated circuits like > uarts) weren’t around during the early days of data transmission. It was > all analog back then, coils, capacitors, and resistors, so then ideas > regarding fast transmission had to wait for the technology to evolve. Then > as ic’s became available, what you could do with them sparked new ideas. > Example: data compression within the modem using a microprocessor, thus > getting higher overall throughput than the theoretical maximum of just the > modulation rate. > > True, though "digital electronics" and "integrated circuits" are not > directly related. Digital circuits were first built with relays and with > tubes. What makes them "digital" is that they deal in ones and zeroes > rather than with continuous real-valued signals. > > paul
