Green screen – all about terminal emulation

Wyse terminals

If you had anything to do with a terminal based computing in the 1980′s then no doubt than name Wyse would be very familiar to you. Founded in the early 80′s in in San Jose, California Wyse achieved it’s early fame as a manufacturer of a very successful line of character based terminals terminals. A key feature of the Wyse range of terminals was the ability to adopt numerous ‘personalities’ of other terminals in addition to their own native modes. Wyse terminals sold very well and soon became the terminal of choice for the reseller community largely due to the resellers’ ability to source terminals from the one supplier and cater for the majority of host systems. As the list below shows, the range of competitor terminals that the Wyse products were able to emulate was extensive:

Wyse 50 – available ‘personalities’

• Wyse 50 native mode
• Wyse 100 mode
• Televideo 910/910+ mode
• Televideo 920 mode
• Televideo 925 mode
• Televideo 950 mode
• Hazeltine 1500 mode
• ADDS Viewpoint A2 mode
• Data General DASHER D100/D200 mode
• IBM 3101-1X mode
• Lear Siegler ADM 3A Mode
• Lear Siegler ADM 31 Mode
• Lear Siegler ADM 5 Mode

Wyse 60 – available ‘personalities’

• Wyse 50 mode
• Wyse 50+ mode
• Wyse 60 native mode
• Wyse 75 mode
• Wyse 100 mode
• VT52 mode
• VT100 mode
• Televideo 910/910+ mode
• Televideo 920 mode
• Televideo 925 mode
• Televideo 950 mode
• Hazeltine 1500 mode
• ADDS Viewpoint 60 mode
• PC Term (PC/AT/XT type)
• Data General DASHER D100/D200 mode
• IBM 3101-1X mode
• Lear Siegler ADM 3A Mode
• Lear Siegler ADM 31 Mode
• Lear Siegler ADM 5 Mode

(Sources :wy-50 Display terminal quick reference guide, wy-60 Display terminal quick reference guide)

Wyse released numerous terminals over the years, and while the Wyse 50 and 60 are undoubtedly the most widely used Wyse would also release color and graphics capable terminals such as the Wyse 160, 350, 370 and 99GT, some of which were capable of emulating Tektronix terminals and IBM PC graphics. These terminals would connect to hosts via serial connection (RS-232) either through a serial port on that host, or a serial adapter card such as those manufactured by Stallion, DigiBoard etc. Later terminal servers which connected to the corporate network were used, extending the distance of the terminal deployment. These hardy serial terminals were used in almost every environment from solicitor firms, offices, retail outlets to factory and shop floors; that is, in both clean and dirty environments.

However as personal computers and networking became more affordable, software terminal emulation packages began to appear on the market which included the ability to emulate Wyse terminals (early examples included TUN from Esker, TTWin from Turbosoft and ICE-TCP from J. River, just to name a few). These emulation packages began to replace the character terminals as more and more PC’s were introduced within the workplace environment.  The most popular emulations (ie wy50/60, ANSI, Dec vt100/102) were all available within these software packages and were primarily used within the small server environments such as those running SCO Xenix and SCO Unix.  Other specialist software companies provided the more sophisticated emulations such as IBM 3270/5250, Stratus, Prime, Unisys and Tandem and others which primarily found use in the mini and mainframe environments.

Perhaps sensing a shift in the market during the late 1980′s and early 90′s Wyse entered into the manufacture of desktop computers (IBM compatible PC’s) and initially achieved a measure of success for the company. However with the entry of competing companies such as Dell and Gateway, whose business models bypassed traditional sales channels and dealt directly with the end customer, Wyse was unable to compete and witnessed a decline in sales that ultimately led the company to withdrawal from the PC market place. Wyse returned to their ‘grass root’ business of terminals and monitors and by 1995, having now acquired rival terminal manufacturers Link and Qume, held more than a third of the general purpose computer terminal market.

In late 1995 Wyse would again change direction and move into the market sector for which they are renowned today. Wyse released the Winterm, a ‘thin client’ which, when combined with a standard VGA monitor, standard PC keyboard and mouse to be attached, was designed to provide the lightweight front end to applications based on a central server.  Running over Ethernet, these units provided the users with higher performance and flexibility and, in my experience, they were predominantly used on factory floors, warehouses and places where a higher degree security was necessary. Thin client display protocols available include HTML, X Window, text terminal emulations (ASCII, ANSI, IBM), Microsoft Terminal Services (RDP) and Citrix (ICA).

Today the promise of desktop virtualization (as developed by virtual environment specialists like VMware, Citrix and Microsoft), Cloud computing and “Software as a Service” are extending the benefits of “thin client” computing. We have come full circle: from centralized computing using terminals, to distributed computing using personal computers and now back to centralized server farms using ‘thin clients’. Ironically it’s not uncommon to see web based terminal emulation software running on a thin client!