In Four-Phase VISION or DATA IV, pressing the Mode key would generally stop the function currently executing. Due to the UNIX architecture, LifeWorks Data Entry was created with this function implemented in a slightly different fashion. Unlike other key functions, this one does not allow normal customization via the termcap files. LifeWorks Data Entry takes a special look at the termcap files with regard to this function.
Section 3.3.14 of the Software Release Guide (SRG) partially addresses this subject but is incomplete. In the case of the keyboard/termcaps noted, the default terminal setup for the BACKSPACE (β) key generates these ASCII codes: unshifted=0177 (DEL), shifted=0010 (BS backspace or Control H), and control=0030 (Control X). This discussion does not address termcaps based upon the Wyse 60 emulation and needs further explanation with the increased use of terminal emulators running on PCs or workstations.
In the general case noted above, there are three keys—BACKSPACE (β), DEL (Delete) and left arrow—and three LifeWorks Data Entry software functions to be assigned—backspace, del char and QUIT. For most termcap definitions, the key and LifeWorks Data Entry function assignments are: LEFT ARROW is BACKSPACE, DEL is DEL CHAR and BACKSPACE is QUIT.
The reason that the BACKSPACE key is the QUIT function is because it generates the special code 0177. When LifeWorks Data Entry reads in the termcap file, it takes a special look at the line defining the 0177. If it sees that it is mapped to 0177 then it sets that code to cause the QUIT interrupt. If it sees that the 0177 is mapped to anything else, it sets 0030 (Control X) to cause the QUIT interrupt. When the QUIT key (either the one producing 0177 or Control X) is pressed, LifeWorks Data Entry gets an interrupt, sets a flag, then the code sees the flag and stops the operation.
The only control you have over the QUIT function via the LifeWorks Data Entry termcap is to choose between the DEL (0177) or Control X (0030). If the line which translates the 0177 (in Section 4 and if using “029” function, also in Sections 6 and 7) is set to anything other than 0177, the QUIT will only occur when LifeWorks Data Entry receives the 0030 (Control X) code. Note that attempting to modify any other line to translate to 0177 will result in an “Inhibited Key” message.
However, if you can change the terminal, or terminal emulator, you may be able to decide which key combination emits the 0177, for example, control END. The terminal setup may let you change the key that produces the DEL character. For example, the TM3200 (tm228/tm229) keyboard setup defaults to DEL/BS can be switched to BS/DEL so that QUIT would be the shifted BACKSPACE key.
Another significant consideration is the use of the “029” function, as this assigns the Control key as the “Alpha” key in conjunction with the “field type override” feature. Pressing Control and a letter produces a code from 0001 to 0032, so there would a conflict if QUIT were assigned to 0027 and “field type override” was in use.