From coff at tuhs.org Sat Jun 20 19:54:04 2026 From: coff at tuhs.org (Edouard Klein via COFF) Date: Sat, 20 Jun 2026 11:54:04 +0200 Subject: [COFF] "On designing finger-friendly interactions" article at aresluna.org Message-ID: <87bjd5zgeb.fsf@gmail.com> Dear old farts, This appeared in my RSS feed and I reckon it will be of interest to most on the list. It goes into the ins and outs of perception and action in human computer interfaces. https://aresluna.org/show-your-hands-honor I hesitated posting it to TUHS, but it's not unix-specific enough, it speaks of terminals, mentions ttys, and uses NeXT as an example, but it's not the core of the topic. Anyway, hope you enjoy it, looking forward to the discussion. Cheers, Edouard. From coff at tuhs.org Mon Jun 22 09:03:46 2026 From: coff at tuhs.org (Douglas McIlroy via COFF) Date: Sun, 21 Jun 2026 19:03:46 -0400 Subject: [COFF] "On designing finger-friendly interactions" article at aresluna.org Message-ID: Mention of the bad old days of half-duplex terminals reminded me of how half-duplex custom distorted capacity estimates for full-duplex Multics. When Multics first began to work, we at Bell Labs found it could barely support three users. Meanwhile, MIT was touting it as already a ten-plus user system, based on extrapolating data from CTSS. There were two major causes for the discrepancy. One cause was that program development bogged the system down; the early PL/I compiler was preternaturally slow. In a vicious cycle, slowness provided motivation to compile in background, thus putting a double load on the system. But slow software was not the only thing that caused Multics to choke. "Think time" between commands was expected to be the same on Multics as in CTSS. In fact, think time could be zero on Multics because full-duplex communication allowed one to type ahead during program execution, whereas half-duplex CTSS prevented typing while output from a running command was possible. Thus a Multics user could burden the system with more interactive commands per minute than a CTSS user could. Doug From coff at tuhs.org Mon Jun 22 09:25:18 2026 From: coff at tuhs.org (Charles H Sauer (he/him) via COFF) Date: Sun, 21 Jun 2026 18:25:18 -0500 Subject: [COFF] "On designing finger-friendly interactions" article at aresluna.org In-Reply-To: References: Message-ID: On 6/21/2026 6:03 PM, Douglas McIlroy via COFF wrote: > Mention of the bad old days of half-duplex terminals reminded me of how > half-duplex custom distorted capacity estimates for full-duplex Multics. > > When Multics first began to work, we at Bell Labs found it could barely > support three users. Meanwhile, MIT was touting it as already a ten-plus > user system, based on extrapolating data from CTSS. There were two major > causes for the discrepancy. > > One cause was that program development bogged the system down; the early > PL/I compiler was preternaturally slow. In a vicious cycle, slowness > provided motivation to compile in background, thus putting a double load on > the system. > > But slow software was not the only thing that caused Multics to choke. "Think > time" between commands was expected to be the same on Multics as in CTSS. > In fact, think time could be zero on Multics because full-duplex > communication allowed one to type ahead during program execution, whereas > half-duplex CTSS prevented typing while output from a running command was > possible. Thus a Multics user could burden the system with more interactive > commands per minute than a CTSS user could. > > Doug I wouldn't want to go back, any more than I would want to go back to full-duplex on a modem, but half-duplex full screen on a 3270 with VM/370 did not seem bothersome to me. Even a 3101 at 1200 baud emulating a 3270 full screen half duplex could be an efficient environment. Charlie -- voice: +1.512.784.7526 e-mail: sauer at technologists.com fax: +1.512.346.5240 Web: https://technologists.com/sauer/ Facebook/Google/LinkedIn/mas.to: CharlesHSauer From coff at tuhs.org Mon Jun 22 10:09:57 2026 From: coff at tuhs.org (Tony Patti via COFF) Date: Sun, 21 Jun 2026 20:09:57 -0400 Subject: [COFF] "On designing finger-friendly interactions" article at aresluna.org In-Reply-To: References: Message-ID: <147e01dd01db$759a8770$60cf9650$@glassblower.info> > Even a 3101 at 1200 baud emulating a 3270 full screen half duplex could be an efficient environment. > > Charlie My first lines of code were typed on a Teletype Model 33 ASR—110 baud, 10 characters per second, and a noisy acoustic coupler connecting me to a remote HP 2000 timesharing system (because, you know, computers were big and expensive back then, to be shared). Five decades later, I still fondly remember the rhythm of that machine. It’s been a long road from those paper-tape loops to the cryptosystems I work on today. Tony Patti https://cryptosystemsjournal.com/