From mboxrd@z Thu Jan 1 00:00:00 1970 From: clemc at ccc.com (Clem Cole) Date: Fri, 28 Feb 2020 17:36:20 -0500 Subject: [COFF] 52-pin D-Sub? In-Reply-To: <6108e507-1dc2-4b09-9121-48c2727513cf.maildroid@localhost> References: <905CE999-5601-4521-847B-B2146C60B564@serissa.com> <6a44c9e7-1e7b-bd0e-df1c-6e2208e8b780@kilonet.net> <6108e507-1dc2-4b09-9121-48c2727513cf.maildroid@localhost> Message-ID: below... On Fri, Feb 28, 2020 at 5:26 PM William Pechter wrote: > Could it be because they all started with current loop tty interfaces? > Most of the old DEC guys started with teletypes. > Very possible... > > Having struggled with a breakout box and different mini and micro vendors > implementations of serial ports... Ugh. And in three-wire the use of > Xon-Xoff varied big time. No standard was the standard. IIRC the IBM > Series/1 had a different 9pin layout than the PC/AR. Why? > RS-232A/B/C was DB-25 P for the DTE (terminating equiment - a.k.a. terminal) and S for DCE (communications equipment - a.k.a. modem). It was standardized. At one time, I (sadly) could quote the paragraph number.... Then in 1978 #$%^& Lear Seglier put a DB-25S on a DTE (terminal). They were the cheap terminal vendor and all hell broke loose. The PC/AT used 9 pin because the back of the unit was small and -- well there could because IBM said so .... But at least the IBM engineers kept to Plug and Sockets from the standard. I did not know the Series/1 used 9 pin. Learn something new. > At least DEC was reasonably consistent until they moved too the Vax > modified RJ design. > Indeed - that was a huge issue - the modified RJ block -- sigh... > -------------- next part -------------- An HTML attachment was scrubbed... URL: