[email protected] (Bill Godfrey) writes: > Back in the 80's I worked at a place that had an IBM 7171 ASCII Device > Attachment Control Unit, to which we could connect terminals like > VT100's and, ISTR, a line from a modem to which a PC running a VT100 > emulator could dial in, logon, and use ISPF. > > From a bitsavers manual: > > The IBM 7171 also provides ASCII to IBM 3270 protocol conversion. > The IBM 7171 appears to the host processor as one or two IBM 3274 model1D > control units. > The attached ASCII display terminals and printers appear to the host > system as IBM 3278 or 3277 terminals and IBM 3286 printers. > IBM 3270 emulation allows the IBM 7171 attached devices to communicate > with IBM interactive packages while utilizing existing 3270 programs > with no host modification required. > IBM 3270 emulation extends the capabilities of the ASCII device by providing > 3270 type functions.
Inside IBM there was extensive use of modified (vm370 passthru virtual machine) PVM to support 3270 simulation .... first on IBM's 3101 glass teletype ... and then later with PCTERM running on ibm/pc (all over the world with corporate home terminal program). vm370 "logical devices" (vm370 device that was actually provided by software running in service virtual machine) and initially used by PVM to provide remote 3270 sessions on the internal network. PVM was then extended to support 3270 sessions simulated on 3101. And then things got really sophisticated supporting PCTERM on ibm/pc ... with all sorts of compression, caching, etc ... to optimize line transmission. 3101 ref http://en.wikipedia.org/wiki/IBM_3101 3101 refs at bitsavers http://bitsavers.trailing-edge.com/pdf/ibm/31xx/ posts with several old emails from 1979/1980 about early topaz/3101 http://www.garlic.com/~lynn/2006y.html#0 Why so little parallelism? http://www.garlic.com/~lynn/2006y.html#4 Why so little parallelism? includes email to fujisawa to get mod.2 upgrades to mod1 boarads http://www.garlic.com/~lynn/2006y.html#email800311 reference to using series/1 to provide 3270 simulation for 3101 terminals http://www.garlic.com/~lynn/2006y.html#email800312 This got incredibly more sophisticated with ibm/pc "pcterm" running on pc; pvm and pcterm kept track of cached strings and could transmit index to cached string ... rather than string itself ... if not cached, then would do transmission huffman compressed strings http://en.wikipedia.org/wiki/Huffman_coding vm370 "logical devices" was also used by the VMSG author for a HLLAPI like facility ... well before the ibm/pc ... old post with parasite/story examples: http://www.garlic.com/~lynn/2001k.html#35 parasite/story to automatigically logon to RETAIN and retrieve all PUT/fixes from RETAIN http://www.garlic.com/~lynn/2001k.html#36 with the CCDN gateway .... a pvm facility simulating (logical device) 3270 to VTAM allowing connections to various corporate non-vm370, sna systems ... all done through standard vm370 logical device support. -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
