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From: bson@rice-chex.ai.mit.edu (Jan Brittenson)
Newsgroups: comp.sys.handhelds
Subject: The internal HP-48 catalog [was Re: Matrix Writer]
Keywords: hp48 internals
Message-ID: <14094@life.ai.mit.edu>
Date: 18 Mar 91 17:00:01 GMT
Article-I.D.: life.14094
References: <27defe95:2377.1comp <27df194c:2377.2comp.sys.handhelds;1@hpcvbbs.UUCP> <11222@jarthur.Claremont.EDU>
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In a posting of [14 Mar 91 19:28:26 GMT]
   bgribble@jarthur.Claremont.EDU (Bill Gribble) writes:

 > speaking of non-programmable functions, does anybody know how the
 > catalog environment works?  since the same object is probably used by
 > the stat and plot/solve routines, it looks like some sort of object
 > filter is passed to the catalog and only certain objects are
 > displayed.

Here are some basics.

   A basic catalog routine is at #47bf0. It is called with two
arguments:

	2: menu.program
	1: items.list

   The menu is an internal menu, which basically is a program
returning a list, which is the menu list. The menu list is a list of
lists, like the CST menu:

	{ { name exec } { name exec } ... }

   Unlike CST menus, the `name' component can be more than just a 21x8
GROB or a string:

	- XLIBs result in the corresponding function name. Useful
	  since it's a relatively short form, it uses the banked ROM
	  instead of the main ROM, and changes whenever a function
	  name is changed. I wonder what happens when a new library
	  is installed with new names but old XLIB numbers? My guess
	  is that certain menus will end up looking different.

	- Programs are evaluated, and return a string or GROB which
	  is used as a label. This is useful for creating the box
	  bullet to indicate a mode (such as in the MODES menu, for
	  instance). There are plenty of functions that take a
	  string, and a true/false value and return a bullet-box
	  GROB label. The program can of course do whatever fancy
	  evaluation it likes to.


   Since the menu is a program that is called whenever the stack is
redisplayed, it can be used to alter the display. Entering a menu can
make you enter a new display, just as easily as the opposite, which
incidentally, seems to be predominant.

   To display the current menu, set the menu argument to @#3ac0
(False). [Note: @#3ac0 here means that you put the Prefixed Machine
Code routine at #3ac0 on the stack, not the binary #3ac0. #3ac0 EVALs
to itself, so #3ac0 SYSEVAL will do the trick.]

Some system catalog menus can be found at:

	PLOT CAT  484fe
	STAT CAT  48544
	TIME CAT  48585


   The items list argument in level 1 is a list of global names. Each
item is a global name which will appear as a tag to its contents. For
instance, "FOO" 'BAR' STO will appear as:

	A:"FOO"

if "slow" catalog mode is enabled, or:

	BAR

if "fast" catalog mode is currently enabled (check to see what system
flag this corresponds to). If the global name doesn't exist, "" will
be used instead in "fast" catalog mode. Arrays appear as a description
of their dimensions. Alarm entries appear as an alarm description.


   Place the menu program in level 2 and the list of names in level 1
and call #47bf0. There are numerous RAM hooks which are used by the
main catalog driver. In fact, #47bf0 only sets up a certain
configuration (as well as saves the previous one in a list in a local
variable). I'm not sure about the usage of all of these hooks, but it
seems possible to create almost any kind of catalog if just properly
configured. For instance, 70614 seems to hold the object to be
evaluated in case of an error. (Notice I say SEEMS here, the issue is
not clear at all.)


   It seems to me what you would want to do is to create a list of
global names corresponding to the file names, using the #5b15 SYSEVAL
(string to global name), and then use the "fast" catalog mode for
browsing. The functions in the menu are called when the corresponding
key is pressed, and the current index is in one of the local variables
(I'm not sure which one - you will have to do some experimentation
here).

Happy hacking!

						-- Jan Brittenson
						   bson@ai.mit.edu

					   Read my lisp: no new classes!