How to use the "WAIT" command



First : Happy New Year for everybody !

How is it possible to show a string on the screen, and to delete it a few seconds after, during the course of a program ?
I explain : when I enter << .... "ABCD" 1 WAIT CLEAR ....>> to show "ABCD" during 1 second, and then to clear the stack, and btw the screen, and after to continue the prgm, it just shows the busy indicator during 1 second, showing nothing, (it executes the CLEAR command before showing the string !).

I sure make a mistake, but even after having read the User's Guide several times, no more idea to fix that pb.

(This question is valid for both HP-28 and HP-48 I own, and probably others)



Hello Jean-Michel,

You can try this:


CLLCD clears the screen
1 DISP displays your message in the first line of the display




The program from Gerson should work. The problem with your intital program is that the HP48 doesn't display anything while running a program. Thus you have to use the DISP command to display something.


Obrigado Gerson, (did you recognize me ?)

(always the same persons talking each other, it's fun !)

I'm sorry, but the problems still remains... Buzy indicator lights during 1 second, while showing ABCD on the top left of the screen, but then only the indicators lights off, not the text...
I know, an HP-28 is not dedicated to strings, but I'd like to get this action. (In fact, I wrote a little program, for me to learn RPL and for my son to learn the tables of multiplication, using the RAND command.)


Special note for everyone interested (or worried ?) by auctions on eBay : I recently bought this HP-28S, in very good condition, for less than 50€. Yes, it's possible, just be patient !


Hello again, Jean-Michel!

Obrigado Gerson, (did you recognize me ?)

Mais oui! (Have you managed to build the serial cable and run the remote control program?)

It seems the HP-28S behaves differently. I am not sure if this is what you want. Anyway, try this inelegant alternative on your HP-28S while waiting for a better solution:

<< "ABCD" 1 DISP 1 WAIT "" 1 DISP "" 2 DISP "" 3 DISP CLEAR >>

You'll have to press the ATTN/ON key when the program stops.




Bon dia, Gerson

(I'm not sure of the writing of "Good Morning" in Portugese)

I thank you, and the others too, for your answers. I'll try your solutions this evening. I will not take the risk to use the SYSEVAL command, even if it's very clearly explained by James in his mail, for the reason that I'm a very beginner in the use of HP's ! I need time to learn...

Jerson : yes, I managed to make a serial link for my '48GX. I used the cable of an old 2 button mouse, it has the exact plug to connect to the '48, connected on a socket onto the card. At the other end of the cable, I used a normal RS232-9 pins cable of an old PC.

I'm now looking for the Kermit software (or a better one ?), for free, of course ! (the same price as the cable, in fact) If someone knows and would be so kind as he leads me to the Nirvana... :-)

I've found something on, but I'm not sure it's the right Kermit software that my '48 ask for. (Always the same problem with me : I'm a beginner...)



If you're using a recent version of MS Windows, then the Kermit-based HPComm "Connectivity Kit" will work for your 48GX. You can also use the faster Xmodem based Conn4x "Connectivity Kit", although for all of its features to work with a 48GX, you'll have to install the included Xmodem server library in the calculator.

If you have HyperTerminal available, you can make either Kermit or Xmodem transfers with that.

Basically, any Kermit application that works with your OS should be okay with the 48 series. I'm not sure, but it may be fussier about which Xmodem (and similar) applications it will work with.



Thank you for the links, James.

I first tried HPComm "Connectivity Kit".
I didn't find there any reference of a driver dedicated to Microsoft Windows XP, only the following :
Microsoft Windows 95/98/2000/NT 4.0. May I use one of these versions, or shall I find another one ?


(The road is long, but each step is interesting !)


I suppose, if you don't mind pressing <- CONT you can run

<< ... "ABCD" HALT DROP ... >>

The halt will halt the the program showing the stack, and then you need to manually CONTinue the program.

The good ol' HP11C did what you wanted just fine. :)



As Dia wrote, with the RPL models, ordinarily the display isn't updated until the calculator is ready for input from the keyboard, with the exception of the CLLCD and DISP commands.

A full display update can be forced even while a program is running by the SYSEVAL equivalent of the SysRPL command SysDisplay though.

Use caution with the SYSEVAL command; the only argument checking that it does is that it has a binary integer for an argument, and then it just executes whatever it finds at that address, whether that makes any sense or not, and misuse may very well cause memory corruption.

In the case of the 28C, be certain that it's in the correct binary integer display mode (HEX, DEC, OCT, or BIN) for the given address when you enter or edit the program, and in newer models use a trailing h, d, o, or b to tell the compiler how to treat the number. Double-check that you've got it right before executing it.

The entry points vary with the model and ROM version. The 28C may have ROM version 1BB or 1CC, and so far as I know, 2BB is the only ROM version for the 28S.

To check the ROM version on a 28C, execute HEX #A SYSEVAL. The same will work on a 28S, or you can use #Ah SYSEVAL.

The entry points for SysDisplay are as follows:

28C ROM 1BB: #13A32
28C ROM 1CC: #13B2C
28S ROM 2BB: #25AFCh
48 series: #386A1h
49 series: #2EF67h

So where you want to force a full display update on your 28S, use:

within your program, and similarly for other models.



Maybe what would be appropriate for you would be something like the following:

%%HP: T(3);     @ ASCII transfer header
\<< @ Begin program
@ Preceding code
CLLCD @ Clear the display
"ABCD" @ String to be displayed
1 @ Line to display string on
DISP @ Display the string
1 WAIT @ Pause execution for 1 second
CLEAR @ Clear the stack (do you really want to do this?)
CLLCD @ Clear the display
@ Following code
\>> @ End program

Edited: 4 Jan 2007, 6:37 a.m.

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