Path: csiph.com!eternal-september.org!feeder.eternal-september.org!nntp.eternal-september.org!.POSTED!not-for-mail From: Lynn Wheeler Newsgroups: comp.os.linux.misc,alt.folklore.computers Subject: Re: what's a mainframe, NYT and Stratus (Re: [OT] Dead DEC Punch card times) Date: Tue, 10 Nov 2026 07:55:29 -1000 Organization: Wheeler&Wheeler Lines: 38 Message-ID: <87a4ngpo4u.fsf@localhost> References: <18dee4b6cab427fa$865$2574533$802601b3@news.usenetexpress.com> <11cr1ub$q796$1@dont-email.me> <11creup$trgi$1@dont-email.me> <11ctde2$2ibp$1@gal.iecc.com> <5O-dnQvUAMIEF2_3nZ2dnZfqn_SdnZ2d@giganews.com> <87eccsppbj.fsf@localhost> MIME-Version: 1.0 Content-Type: text/plain Injection-Date: Tue, 10 Nov 2026 17:55:34 +0000 (UTC) Injection-Info: dont-email.me; logging-data="2497553"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+bWd3TeYHrftqtqSZwDD9VJBXHdFC/7vk="; posting-host="79a5ac4974d049d0c74487c0d80bb5d5" User-Agent: Gnus/5.13 (Gnus v5.13) Cancel-Lock: sha1:NmERCqxL9PyKfq0bxgf/UNbzSEo= sha1:K83Xd4f+sVW+uvx7TaTxQYvFctU= sha256:4iDWB3lCvDhoH9x2+mxxOkDVMDIpPwFrSxLBRrrCksk= sha1:yhI6Qy6TAym1e7+IJPuo0tuuox4= sha256:XDZuUoq0BmLvBaAlE6U987P1/j97RNdCTCg3n2BVoVg= Xref: csiph.com comp.os.linux.misc:95432 alt.folklore.computers:236730 Lynn Wheeler writes: > Note: 1980, IBM STL (since renamed SVL) was bursting at seams and 300 > people/terminals from IMS group were being moved to offsite bldg, with > dataprocessing service back to STL datacenter. They had tried "remote > 3270" but found human factors totally unacceptable. > > I get con'ed into doing channel extender support, allowing placing 3270 > controllers at offsite bldg with no perceived difference in human > factors. Unanticipated side-effect was the associated systems' > throughput increase 10-15 percent. STL had been speading 3270 > controllers across all channels with 3330 drives. The channel-extenders > (operating full-duplex) significantly reduced the channel busy > interference with the 3330 drives (for same amount of 3270 traffic; > there was some consideration moving all 3270 controllers to > channel-extenders). Note once the 3033 was out the door, the processor engineers start on trout/3090. They configure memory, processor, channels, I/O to meet specific throughput goals. However, in San Jose, the administration dictated that the 3880 disk controller would use a (really slow, resulting in significant channel busy) vertical CISC processor (much slower than the previous processor in 3830 controller). The 3090 people thought the 3880 would be the same as 3830, but supporting 3380 3mbyte/sec transfer, when they found out how bad the 3880 controllers' channel busy was (there is significantly amount of half-cuplex channel protocol back&forth undernearth the covers with latency playing increasing role), they realized they would have to significantly increase the number of I/O channels in order to achieve system throughput targets ... which required an additional TCM (3090 said semi-facetiously they would bill the 3880 organization for the increase in 3090 manufacturing cost). Marketing eventually comes up with what a fantastic I/O machine the 3090 is with big increase in number of channels (but it was actually role played by slower 3880 controller and increase in channel busy associated with protocol chatter). -- virtualization experience starting Jan1968, online at home since Mar1970