Scorpio News |
January–March 1988 – Volume 2. Issue 1. |
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that itself asked ‘W/w’, and which on exit asked:
“BACKUP DONE – PROCEED (with original command)?".
I have now completely changed the system of command access. The philosophy now is that any command that can cause a disk operation, cursor movement, printer output or change the printer or screen format is protected in some way.
All lower case (a-z) commands, except “f”, are converted to upper case, allowing great shortening of the dispatch table code. Protection is applied to ALL A-Z commands EXCEPT I,J,M,D,F,f,V. (M,D,F,f require parameters anyway, so they can be aborted, and I,J and V commands do not cause serious problems if invoked in error.)
The remaining A-Z commands can have unwanted results if accessed in error, so they are ALL accessed via a lead-in key. I have chosen ‘^Q’ for this purpose, since it was not used as a command, and ‘Q’ is near the control key. A small amount of extra code has been added which has widened the scope of this, so that a total of four key sequences are available to access the required protected commands. e.g.;
^QE or ^Qe or ^Q^E or ^Q^e keys will ALL access the ‘E’ command.
Where the command in question can have particularly awkward results, such as ‘E’, ‘W’, ‘K’ etc.;, a further prompt is printed for security. Since most of these extra security keys are only used a few times in a session, this double protection is not a problem.
In some cases like formatting, the ^Q protected command requests extra parameters, and so this request provides a way of escape, without the need for GEMPEN to ask if it is safe to proceed.
a) F/f – Find and Replace
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