Emu28 - A freeware HP18C/28C Emulator
for Windows 9x, ME, NT, 2000, XP, Vista, 7 and 8

1. General

Emu28 is based on the sources of Emu48 and is an emulator for the Hewlett Packard Clamshell calculators HP18C and HP28C hardware. These calculators are based on the 1LK7 Saturn CPU, the 1LP2 Centipede and 1LP4 ROM chips. The HP18C isn't tested, because I have no ROM image of it.

2. Acknowledgements

A big thank to Cyrille de Brebisson for his technical assistance and to Jean-Francois Garnier for his work on the HP28C. Also thanks to Sebastien Carlier for his Emu48 v1.0, without him this emulator would never have been created. And finally I want to thank all the unnamed authors for publishing material about this calculators.

3. ROM Images

You need ROM images. The ROM images are copyrighted by Hewlett Packard and I have no license to distribute them. Please don't ask me, I will not send you mine.

ROM images are valid in a packed (even address lower nibble, odd address higher nibble) or unpacked (one nibble per byte with even address first) form. They can be validated with the CHAMPCHK.EXE command line utility. To do that, start a Command Prompt while running Windows, and type:

Champchk <image-file>

where <image-file> is the ROM image you want to test. As result you will get a report of the ROM checksums.

4. Installation

To install Emu28, just unzip the emulator and the required emulator skins into an empty directory. Finally copy your ROM images into this directory and adjust the ROM image name to the name used in th corresponding KML script. When you first run Emu28, it will detect the directory in which you installed it, and will write the configuration to the registry at HKCU\Software\Emu28.

5. How to Start

When Emu28 is installed and you have put the valid ROM image(s) into your Emu28 installation directory, you can start Emu28. You'll see a "Choose Your KML Script" box.

KML scripts in fact define the visual aspect of Emu28, the behavior of the buttons, of the keyboard, ... It's a GREAT way to customize your copy of Emu28.

Check that the path in the "Emu28 Directory" text area is correct. Modify it if the directory in which you installed Emu28 is not the directory displayed. Click the refresh button ("V") after modifying it to update the list box or use the ("...") button to start the directory browser.

Choose a KML script in the list box for your calculator ROM you put into Emu28's directory.

Available scripts from the author at the moment are:

If you are interested in writing new scripts, get the KML 2.0 documentation from the authors Emu48 page.

Once you have selected a script, press OK to start the emulator. In most cases, when Emu28 crash after pressing the OK button, you are using an invalid ROM image. While it's running, you can use the View/Change KML Script... command to change the visual aspect of Emu28.

6. Command Line

The command line syntax is "Emu28 [file]". The parameter sets the filename for the emulation data independent from the "LastDocument" setting. The argument is optional.

7. Virtual Keyboard

There are two ways to use the virtual keyboard on the emulated calculator:

  1. by Mouse
  2. by PC keyboard

The easiest way to use the emulated calculator is using the mouse. The KML script define buttons with an area where mouse input is active. The mouse cursor change from an arrow to a hand cursor in these areas. The state of the virtual key follow the state of your left mouse button. When the mouse cursor leaves the virtual key area the virtual button automatically release. In some cases you need to press more than one key on the emulator. For these cases press the virtual key with the right mouse button. When you release the mouse button or leave the area of the virtual key, the key is still hold. To release all hold virtual buttons, just use the left mouse botton again. A single release of a hold virtual key isn't possible.

Another convenient way is using the PC keyboard. The KML script language support a large variety of commands to implement this feature. So keyboard usage depends on your used KML script and not on the emulator. Because of this it's impossible to say what's happen when you press a key on the PC keyboard. For further details read the KML 2.0 documentation mentioned before please.

8. File Menu

8.1 New...

Creates a new emulation session. You're asked for a new KML script where you can select the calculator type and skin to emulate.

8.2 Open...

Opens an existing emulation session. The emulation continues at the same position where the loaded session was aborted.

8.3 Save

Saves the current running session with the actual name.

8.4 Save As...

Saves the current running session with a new name. You're also get in this dialog when you Exit a new session without a state file name.

8.5 Close

Closes the current session without closing the emulator.

8.6 Settings

This calls the Settings dialog. This dialog has three sections: General, Disassembler and Sound.

8.6.1 General section

8.6.2 Disassembler section

Choosing the assembler syntax:

8.6.3 Sound section

A new implementation of the sound engine made ROM patches for sound output obsolete. The new sound engine emulates the behavior of the beeper output ports and only work in connection with a sound card. Using the internal PC speaker isn't possible any more. The old beeper method with a ROM patch is still working but deprecated, it's strongly recommended to remove all beep patches from your current KML scripts to enable the new sound engine. The support of the old sound implementation by a ROM patch maybe removed in later versions of the emulator and remaining beep patches will corrupt the ROM with an illegal opcode then.

For the sound generation the calculator must know his own CPU strobe frequency. On the real calculator the speed depends on various settings like component tolerances, actual temperature, humidity and other variables. The resulting speed is measured by the calculator firmware at a cold- or at a warmstart and stored in the =CSPEED variable. The content of this calculator variable has direct influence on the resulting frequency and duration. On the emulator the CPU strobe frequency is set by the registry key HKCU\Software\Emu28\Emulator\SaturnCycles. The content of this variable multiplied with 16384 is the CPU strobe frequency in Hz used by the emulator. Because older versions of the emulator were not able to measure the CPU strobe frequency properly or the content of the SaturnCycles has been changed since the last measurement, the =CSPEED variable of this session file may contain a wrong frequency value. You easily may discover this by measuring the real duration of a 10s beep. Is the difference to 10s less than 1s everything is ok, if not, you should perform a warmstart of the calculator in this session file. Alternatively you may execute a Reset Calculator. This recalls the measuring routine and save the result in the speed variable. Both restart variants purge the stack content!

8.6.4 Infrared Printer

The emulator has the ability to print data to a HP82240A/B printer simulation. The data transfer to the printer simulator is done over UDP. In this section you can the define the IPv4 address and the port the printer simulator is listening. A suitable HP82240B printer simulation can be found here.

8.7 Exit

Quit emulation. The default actions at finishing are defined in the Settings dialog. If the current session is "Untitled" you are asked for a session file name using the Save As... dialog. If you quit the emulator without a given filename, you're asked for choosing a KML script at next startup.

9. Edit Menu

9.1 Load Object...

This is only valid for the HP28C emulation. You can load HP28C binary objects to stack level 1. Therefore the object must begin with "HPHP28-C". If the binary header isn't present, the object is loaded as string. Dropping HP objects over the emulator window will also load objects. Be sure that the emulator isn't busy before doing this.

9.2 Save Object...

This is only valid for the HP28C emulation. Save the current object in stack level 1 as HP28C binary object to disk.

9.3 Copy Screen

Copy the screen content to the clipboard.

9.4 Copy Stack

This is only valid for the HP28C emulation.

Copy a "Real Number", "Complex Number" or "String" object in stack level 1 to the clipboard. On all other objects, the command will be ignored. This prevents sending binary objects to the clipboard.

The decimal point (radix mark) of "Real Numbers" in the clipboard is equal to the calculator setting. This point maybe important when you try to paste the numbers into a program using the locale settings of the host operating system.

9.5 Paste Stack

This is only valid for the HP28C emulation.

Paste the text field content of the clipboard to stack level 1 of the emulated calculator. If the clipboard content is representing a real number, the number will be saved as "Real Number" object. Is the content a complex number object, the number will be saved as "Complex Number" object, in all other cases as "String" object.

To import "Real or Complex Numbers" from the clipboard, the decimal point (radix mark) of the clipboard and calculator must be equal. A real or complex number is only detected in the case of valid real number characters in the clipboard. Especially heading and tailing white spaces aren't valid number characters also.

Complex numbers must be in the form (a,b) when using the point radix mark or in the form (a;b) when using the comma radix mark. The Cartesian or algebraic form a+bi is not supported.

9.6 Reset Calculator

This emulates the Reset pin of the internal CPU.

9.7 Backup

9.7.1 Backup Save

This saves the current emulator status into a backup slot. If the backup slot already contain data, it will be overwritten.

9.7.2 Backup Restore

This restores a previous saved emulator status without request. If you changed the calculator model meanwhile, the emulator will switch back to the old model.

9.7.3 Backup Delete

This deletes the data in the backup slot.

10. View Menu

10.1 Change KML Script...

This allows you to change the skin of the current emulated calculator. In opposite to the New... command you see only scripts emulating the same calculator.

11. Tools Menu

11.1 Disassembler...

This is a simple disassembler.

Enter the address to disassemble in hexadecimal into the "Address (HEX)" field and press <Return>. With the "Next Address" button the next opcode is disassembled. With the "Copy Data" button you can copy all selected lines inside the list box to the clipboard.

11.2 Debugger...

The assembler code debugger of the emulator. For more details refer to the extra documentation of the debugger please.

11.3 Macro

The keyboard macro recorder unit.

11.3.1 Macro Record...

Prompts a dialog to enter the macro file for the data to record. After accepting the confirm message, every key event is recorded into the macro file with it's time information.

11.3.2 Macro Play...

Prompts a dialog box to ask for the keyboard macro file to play. The replay starts immediately after selecting the file.

11.3.3 Macro Stop

Stops recording or replaying a keyboard macro file.

11.3.4 Macro Settings...

Settings for the Macro Replay mode

12. Help Menu

12.1 Help Topics

Call this document.

12.2 About Emu28...

The version, copyright and license message...

13. DDE Server

Emu28 has an integrated DDE server to transmit data from and to the HP stack. Because only the HP28C has a stack, all DDE transfers are ignored on the other calculators. You have the same restrictions like with the commands "Load object..." and "Save Object...", that a running program may corrupt memory. In difference you can choose the stack level for the transfer in the DDE item field. Take care to transmit data only after the acknowledge of the last DDE transaction.

Technical data:

Servicename: Emu28
Topicname: Stack
Item: 1 (stack level)
Clipboardformat: "CF_HPOBJ" (user defined)

The DDE commands CONNECT, POKE and REQUEST are supported.

The structure of the clipboard format "CF_HPOBJ":

4 Byte (length of object, LSB first) HP object (normal HP object)

14. License

Emu28 - A HP18C/28C Emulator
Copyright (C) 2016 Christoph Gießelink

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.