Blueprints Application design for asynchronous workstations
From "VS Workshop",  Access to Wang, September 1990
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One of the facts of modern VS life is that many users are no longer seated before an standard Wang workstation connected locally using coaxial cable. Instead, emulations of the basic Wang terminal types have replaced these standard terminals, offering the user remote access, concurrent PC-based applications, local printing, and other advantages. Instead of long rows of 2256Cs, many VS shops now have a rich mixture of workstations, including PCs with local terminal emulation cards, PC Local Area Networks accessing the VS through communications servers, or even Apple Macintoshes emulating 2110 asynchronous workstations.

Developers of VS applications (including Wang) have largely ignored this shift in terminals, even though there are some important features and limitations posed by each type. These differences alter the functionality of applications, and can even interfere with an application's use by offering a distracting screen appearance or requiring confusing alternate key sequences.

My purpose this month is to examine some of these considerations so that software designers can recognize ways to improve the usability of their products with non-standard terminals. I will concentrate on workstations that are modeled after Wang's 2110 terminals - including the 2110A, 2256A, and support for VT-100 terminals.

The 2110 workstation defined

Several years ago, Wang introduced the 2110 workstation type and related asynchronous controllers. Pitched as cheap workstations, they could be attached locally or used through standard asynchronous data communications equipment, allowing remote users most of the advantages of a local workstation. Variations on the 2110 standard were introduced later, including the 2110A (a 2110 with an attached printer port) and the 2256A (a 2110 terminal capable of Word Processing when used with a enhanced controller).

In addition to providing the first realistic means of dial-up usage, the 2110 standard also opened up the VS to other computing users by accepting industry-standard terminals - ANSI 3.64, a.k.a. the VT-100 - as well as the proprietary 2110 type. VT-100 terminals dominate major portions of the computing world, so there is potential for offering VS access to a significant number of users.

While there are many possible variations in 2110 terminal usage, there are some basic characteristics in common. 2110 terminals use a screen of 24 rows by 80 columns and do not support color controlled from the host. Many users are emulating 2110 terminals through software run on an IBM-compatible PC, often using a color monitor. Many use industry-standard keyboards - not Wang keyboards with their unique key arrangement - and must use alternate key sequences when PF keys or other Wang key functions are required. A large number are remote users operating at a much reduced transmission rate compared with a local workstation.

Guidelines for application design

The following guidelines are intended to make applications more generic to meet the needs of 2110 users:

1. Avoid using column 1 or 80. Many terminals do not display a full 80-character line, and the VS workstation requires a leading character for the Field Attribute character. Consider your workstation area to consist of columns 2 through 79, not 1 through 80.

2. Avoid underlines. Underline attributes are not directly supported on DOS-based workstations using color monitors. 2110 emulation software typically substitutes color for underlined characters; this results in a confusing screen appearance when there are many underlines on a page. For example, the monthly calendar application I use resembles a grid when run on a local terminal, but is reduced to a confusing mass of alternate colors when run from a 2110 dial-up connection.

In some cases, a dashed line can substitute for the underlines - though this technique robs the designer of an additional line and does not look as pleasing. It may also be possible for some PCs using VGA monitors to simulate the Monochrome Graphics Adaptor (MGA) or Hercules mono graphics card; this is the approach I use when I need to see underlines as the software designer intended.

3. Avoid shifted PF keys. Most 2110 users are using non-Wang keyboards and must already translate PF key values to their software's alternates. It's difficult enough to master alternate key sequences without requiring more than the usual 16 keys. Use as few of the PF keys as you can in 2110 applications.

4. Don't assume PF key placement. Those who have spent much time on Wang keyboards have grown accustomed to the four-key spacing of the PF keys. With this understanding, finding a new PF key amounts to determining its group on the keyboard and the position within that group. This works well until the user is confronted with a non-Wang keyboard and must think of the numerical value of the key instead. It's always best to put the number value on the screen for clarity.

Wang has recently made this problem worse by using an up-arrow to indicate the shifted version of a PF key. For example, the CONTROL utility main menu allows you to modify a field by pressing PF 4. The option to modify the header is PF ^4 (shifted PF 4; i.e. PF 20). The numerical manipulation required to come up with these values can be very tiresome. (Quick! What's the numerical equivalent of PF ^13?)

5. Allow other control options. If possible, allow the user to select whether to use PF keys or some other form, such as typed commands or short mnemonics. Properly chosen, these control options might even work well for all users - even those with VT-100 terminals.

6. Consider tab-stop menus. Tab-stop menus resemble Word Processing menus, with items placed in columns and a tab placed in front of the item. Normally, the user must use the tab key to place the cursor on the desired item, then execute the choice by pressing ENTER. Like Multi-Station terminals, 2110/2110A terminals allow a faster approach: simply type a letter and the cursor will hop to any tabs where that letter is used in the description. Since this feature is provided by the VS controller, even VT-100 users can use this type of menu; thus, tab-stop menus offer an easy way to sidestep problems of workstation compatibility by eliminating the need to support alternate PF keys.

While Multi-Station (MWS) and 2110 terminals can both perform this trick, MWS terminals can only access items in the same column as the current cursor position. 2110 terminals can find any occurrence of the letter on the page.

7. Limit the number of words on the screen. VS software typically assumes a locally-connected terminal working on a fast coaxial connection. In such circumstances, the amount of information transferred to the screen is of little consequence to the user. This transfer becomes more critical when the transmission speed is lower, as when dialing into a VS on a asynchronous connection. For example, my programming menu has 32 items and full descriptions for each; it takes over fifteen seconds to rebuild the screen every time I return from a program.

If you expect much dial-up work, you should reduce the amount of information that must be passed between the terminal and the host. If possible, you might consider a "brief" option to your menus that would allow the experienced user to pass directly through intermediary menus and go directly to an option several levels in.

8. Special requirements for VT-100 support. If you are considering use of VT-100 terminals, try to use the most generic approach possible. Avoid all use of PF keys or other unique Wang key functions like EXECUTE, stressing command-driven or tab-stop selections instead. Provide alternates to the Command Processor for common functions like printing and procedure queue control.

Other workstation characteristics

2110 terminals represent only one way that users are migrating from standard VS terminals. Other combinations include variations of the Wang Local Office Connection (WLOC) and the Windows version of WLOC (WINLOC). I will cover these specifications next month and also offer a quick menu program for testing screen design strategies.