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Application design for asynchronous workstations - Part II

From "VS Workshop",  Access to Wang, October 1990
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Last month I reviewed some possible design goals for applications where non-standard terminals might be used. This month I will continue with some of the constraints and features of PCs acting as local VS terminals, using connection approaches such as the Wang Local Office Connection (WLOC) and WLOC for Windows (WINLOC). I'll also cover keyboard choices, visual alternatives to PF key selection, and more discussion of the use of ANSI (a.k.a. VT-100) terminals for VS access.

Keyboard support

The type of keyboard used has a great deal to do with the difficulty of using standard VS applications. If the PC is equipped with a Wang keyboard, there is little impact. Industry- standard keyboards require the use of alternate approaches for Wang-specific key functions, since typical keyboards have only ten function keys and are missing the CANCEL, EXECUTE, HELP, NEW LINE, and GL keys. In other words, the situation is similar to that of the 2110 user: complex and confusing alternate key sequences may be required in order to perform simple functions. For example, PF16 is the most common key needed (after the ENTER key), and it is easily found on a Wang keyboard. Using a standard PC keyboard, however, it would require holding the ALT key and pressing F6 - hardly as memorable.

Shops that make extensive use of PCs and industry-standard keyboards should consider limiting the amount of function key selections needed for daily use to ten or less. Tab-stop menus are one possible compromise, since they can be used in any situation. Access to the Command Processor (HELP) screens remains a problem, since there is no easy alternative to the PF key selections there; alternatives such as print managing software should be considered to limit the need for HELP access.

It is also possible to create "menu bar" selection software that is used with a mouse to selection Wang special key functions. Such utilities are usually Terminate and Stay Resident (TSR, or "pop-up") programs that present a scale of items for the mouse user to select from. This is also an approach used by the Windows version of Wang's WLOC software and 2110 emulation products for the Apple Macintosh - more on both of these approaches below.

Local connections: the WLOC board

Wang's WLOC product is a board and related software that allows a PC-compatible to act as a local VS workstation. The WLOC card uses a coaxial cable (e.g. '928') connection - or the equivalent baluns and twisted-pair wiring - and operates at the normal speed when communicating with the VS.

PCs using the WLOC board to act as workstations behave much the same as any other terminal. There are complications introduced by the circumstances of the PC operating environment, however, including screen support for underlines and special characters and possible use of internal diskette drives and printers.

As with 2110 products, PCs using WLOC software and color monitors are not able to show normal character attributes such as underlines, highlights, blinking fields, etc.; instead, colors can be assigned to represent these attributes. The WLOC software allows control of these colors through arguments passed to the WLOC program when it is run. Since it is not known what individual users have chosen for these values, application designers may not be able to rely on the use of these attributes to convey important information.

PCs using WLOC cards can also act as archiving workstations for Word Processing files. This feature allows the user to copy (and optionally delete) WP documents from the system without access to a system disk drive or special transfer software. The diskette drive can be either the a: or b: drive, and the diskette produced is written in the 5-1/4" archive format used by VS system consoles and Wang OIS systems. Like screen colors, access to the archiving function is through arguments passed to the WLOC program. (High- security environments may find this troubling, since archiving capability is available to any locally-connected PC with access to MS-DOS and VS Word Processing; there is no way I know of to block the potential use of this feature.)

If the PC has a printer attached, it can be used to print screen dumps in the same manner as with most MS-DOS applications. File transfer software can be purchased from Wang and third parties to allow full use of the PC printer and its features - as with all of the 2110 emulation packages. Files transferred using such software benefit from the speed offered by the 928 connection.

WLOC enhanced: WINLOC

Wang also offers WINLOC, a variation of WLOC made to work as within the Microsoft Windows Graphical User Interface (GUI). As a Windows product, WINLOC offers the ability to cut and paste between other Windows applications and simultaneous use of several PC applications. The screen approach used by Windows is through graphical rather than text modes, and underlines show properly. (Blinking and bright characteristics must still be shown with alternate screen colors.) When "maximized" (set to its largest dimensions), all rows and columns appear; this view may be reduced by the user.

WINLOC also allows a mouse-driven approach to Wang special key support: through pull-down selection menus and direct access to screen labels. The WINLOC application includes pull-down menus for all PF keys and most other Wang-specific functions. The user simply selects the menu time, selects the item from the menu bar, then clicks the mouse pointer on that function name. With practice, this action becomes almost as fast as working with PF keys.

Screens that have been carefully formatted can also act directly as command menus. For example, a PF key can be accessed from a menu by positioning the mouse pointer on the associated number and clicking. Some other functions can also be accessed this way, as shown in Figure 1 (below). Note that the formatting requirements are rigid; spaces and leading zeros can often rule out the use of this approach. (Some 2110 emulation products for the Macintosh also offer this feature, but may vary in what they accept. Check the documentation for further information.)

More about VT-100 terminals

If you have need to use a VT-100 terminal or emulation product (a.k.a. the ANSI 3.64 terminal), Figure 2 shows some alternate sequences for Wang key support. My intent in presenting this list is to show that there are ways of using these terminals; in practice, though, the key functions would have to be aided with macros or keystroke glossaries.

In summary, I believe that a good measure of the success of software can be user comfort in using it. By carefully considering the workstation and accompanying environment, the prospects for this success can be improved.

Figure 1: Suggested Labels for Mouse Access to Wang Application Screens

The following screen labels work with Wang Local Office Connection for Windows (WINLOC):

Valid PFKey Labels Invalid PFKey Labels
PF1 PF 1
PF16 PF 16
1) 01)
(1) (01)


Other valid key labels

Figure 2: ANSI Key substitutes for Wang Key Functions

The following key sequences can be used to access VS key functions while using a VT-100 terminal or emulation product. All commands shown here begin with the ESCAPE and left square bracket keys.

VS Function Keys
RESET ESC [ 99 p (note lower case)
HELP ESC [ 0 p ( " " " )
PFnn ESC [ nn p (where nn = PF key value)

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Copyright © 1990 Dennis S. Barnes
Reprints of this article are permitted without notification if the source of the information is clearly identified