May 13, 2014
iPad 3000 terminal emulator gains NS/VT
The only tablet-ready terminal emulator for HP 3000 users has crossed over even further into the language of MPE. The 1.1.0 version of TTerm Pro adds HP's 3000-specific Network Services/Virtual Terminal protocol. The new feature means that many more MPE applications will run without a flaw over the Apple iPad tablets.
To be exact, the latest version of TTerm Pro will run under iOS7, so it's possible that some other Apple mobile product could link up this app with a 3000. But a tablet is pretty much the minimum screen real estate for a terminal emulator. Jon Diercks, who tested the previous version of TTerm Pro, said in his review that an external keyboard connected via Bluetooth eased the use of tablet-based terminal emulation. But the screen capture at left -- collected back when TTerm Pro only did Telnet links -- shows you can even get a soft keyboard, plus function keys, onto an iPad's screen.
Turbosoft, which released a 3000-ready version of the iPad app last year, has lowered the price of TTerm Pro by 50 percent. It now sells for $24.95. Any 3000 managers who purchased the app last year can update it -- with its new 3000-savvy -- for free. NS/VT could be worth a lot more for any company that wants to preserve a 3000 application's capability to go mobile.The earlier version of TTerm Pro supported only Telnet connectivity, which meant that the longest-standing 3000 apps would not run in the iPad-based emulator. Mind you, this is not an emulator of the base 3000 PA-RISC processor, a la CHARON. This iPad app emulates HP's proprietary terminals for the 3000, specifically the HP 700/92 series.
The MPE applications which were tuned the finest for 3000 users relied upon NS/VT protocols. The protocol was developed by HP as an emulation itself: NS/VT gave users on Local Area Networks the same kind of performance and reliability only available through an ATP card inside a 3000. By using NS/VT, an application didn't require that a 3000 have that card.
AICS Research developed a QCTerm emulator during the late 1990s which relied upon Telnet for its network protocols. But AICS founder Wirt Atmar knew very well how much advantage NS/VT held over Telnet. Full-duplex is being emulated via NS/VT, and that ensures the delivery of data.
Full-duplex has traditionally been by far and away the preferred protocol for communication with a host computer, because you have this very strong reassurance that the host did indeed receive the character. The host's retransmission of the character back to you is an explicit verification that it saw and absorbed the character you just typed.
NS/VT is an HP-proprietary client/server protocol — but it is also nothing more than a simple and obvious extension of the design philosophy that had begun with the ATP card, where a remote processor transmits a line of text to the HP3000's CPU only when that line of text is complete.
Two ways are commonly available today to use NS/VT-like services. One requires the use of a DTC (data terminal controller), the other a terminal emulator. In both, the function of the original ATP card is being faithfully recreated. When you serially communicate with a DTC, a processor located on the DTC's serial card is absorbing every character you type and echoing it back to you. Only when a termination character is typed, or the line buffer is full, or a time-out occurs, is your line of text transmitted to the HP3000 as a single packet of information via the LAN that connects the DTC to the HP3000.
An NS/VT-based terminal emulator is maintaining essentially full-duplex communication with the DTC serial card — or your PC's memory. Every character you type under NS/VT is immediately echoed back to your screen. Only when you strike the carriage return (or the enter key) is your line of text transmitted over the LAN to the HP 3000. "Turn-around times" are so quick on a LAN (if it's not too busy) that you don't tend to notice the nature of one-way communication inherent to a LAN.
According to the ubiquitous management manual The MPE/iX System Administrator's Handbook, NS/VT is a better choice for applications on 3000s. "It usually yields the best overall results, because it is optimized for the way most MPE applications work," the book states in its Getting Connected section. NS/VT is enough of an emulation specialty that Attachmate offers the WRQ-developed Reflection as a separate Reflection HP product. The chief difference between the rest of the Reflection line is that NS/VT is included in Reflection HP. There's an uplift in price for this capability.
TTerm Pro includes NS/VT along with Telnet protocol. It's pretty obvious a company isn't going to replace all of its terminal emulator desktops and laptops with iPads. But it's a real help to know the protocol optimized for the HP 3000 now has a way to run on mobile tablets. Consider that previous sentence for a moment. Then decide how often technology continues to flow back to the world of MPE. Instead of $249 a seat, terminal emulation now costs $24.95. And upgrades are free if you're using an Apple tablet.
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