The X-Philes (2nd Revision)/The X-Philes Number 1 (1995).iso/xphiles/hp48_2/vector.ent

Text File | 1991-04-12 | 2KB | 42 lines

Article 1433 of comp.sys.handhelds:
From: [e-mail] (William C Wickes)
Subject: HP-48SX Vectored Enter
Date: 12 Mar 90 21:21:55 GMT
Organization: Hewlett-Packard Co., Corvallis, OR, USA

The HP-48SX manuals do not document a very powerful feature that we call
"Vectored ENTER," that allows you in effect to redefine or bypass the
command line parser and to have a shot at the stack etc. after the command
line has been executed.

Keys that execute an automatic ENTER perform a two-step process:

1.  The command line is parsed and evaluated.
2.  The key definition is executed.

When flags -62 and -63 are both set, the system extends this process as
follows:

1.  The current path is searched for a global variable named *aENTER
(here "*a" is the Greek alpha character--character 140).  If present,
the command line is entered as a string object and *aENTER is
executed.  If absent, the command line is parsed and evaluated
normally.

2.  The key definition is executed.

3.  The current path is searched for a global variable named *bENTER
("*b" is Greek beta--character 223).
If present, then a string representing the key definition is put on the
stack, and *bENTER is executed.  The string is the key definition
object's name if it is a command, XLIB name, global or local name, or
an empty string for other object types; its primary purpose is to implement
things like the TRACE mode on other calcs, where you can print a running
record of what you do.

A simple example of the use of *aENTER is to create a more convenient
binary calculator, where *aENTER slaps a "#" on the front of the command
line so you don't have to bother when entering numbers.