A real emulator of the virtual HP-72S and HP-74S

Warning: The HP-72S and HP-74S have never been released by HP,
and - to the author's knowledge - no such project ever existed in HP.
All the information about the hypothetical HP-72S and HP-74S below are pure speculations.


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HP-72S and HP-74S presentation

The HP-72S and HP-74S are hypothetical HP BASIC handhelds that would have been the successors of the HP-71B.

The documents below are early attempts to define the hardware specifications of these machines:


<detailed hardware internal specification to be available>



Summary of the enhanced functionalities of the HP-72S:


Enhancements related to the new display:

-   2-line display forming a single 44-character user line,

-   WINDOW statement expanded to manage the 44 display positions,

-   GDISP statement acting on the full 44-character line for full graphic capabilities.


Built-in additional keywords:

-   equivalent to the HP-71B CUSTUTIL & STRINGLX LEX files,

-   most common and useful HP-71B extension functions such as:
KEYWAIT$, STD$, MSG$, RPT$, REV$, TRIM$, LWRC$ and more.


Other enhancements:

-   faster key repeat rate,

-   non-rolling command stack for better use of HP-IL displays,

-   ports 6 and 7 now accessible, e.g. CAT :PORT(6.01),

-   MOD modulo function usable as an operator, e.g. 1024 MOD 7,

-   RENUMBER keyword can be shorted to RENUM or just REN,

-   new more legible SHOW PORT format,

-   new keystrokes to get the missing \ | _ ~ and ` characters,


<detailed user documentation to be available>





Emu72 for Windows - Beta version 0.91 - April 2021

Emu72 is based on Christoph Giesselink's great Emu71 emulator.


Supported machines:

Emu72 supports the following virtual machines:

-   HP-71B+ : a slightly redesigned HP-71B based on the same 72S/74S hardware architecture.
Differences vs the HP-71B are: one 32K RAM device in port 0 instead of the old 4 x 4K ports,
HP-IL in port 6 (instead of end of port 0), CPU speed increased to 1MHz,

-   HP-72S : fully functional, according to the documentation above,

-   HP-74S : this prototype version uses the HP-72S ROM for the same functionalities,
so only the bottom line of the multiline display is managed.



This preliminary emu72 version doesn't provide an automated installation procedure.

The procedure for installation is:

-   install the latest version of Christoph's Emu71,

-   copy the content of the emu72 and rom72 zip files (see below) into the folder where the emu71 executable
is located, usually "C:\Program Files (x86)\HP-Emulators\Emu71",

-   optionally, create a short-cut to emu72.exe on your desktop.


Opening a new HP-71B+, HP-72S or HP-74S in emu72 creates a simple core machine with 32K RAM without HP-IL.

To properly emulate the target machine, do the additional manual steps:

-   HP-72S: add one more 32K RAM device in port 0, providing a total of 64K RAM,

-   HP-74S: add three more 32K RAM devices in port 0, providing a total of 128K RAM,

-   all machines: add the HP-IL ROM in port 6.


You can then add more RAM or ROM modules such as the Math ROM, JPC ROM or FORTH/Assembler in any of the ports 1 to 5.

Port 6 is assumed to be dedicated to the HP-IL module slot (although other ROM/RAMs can be plugged in that port in emu72),
and port 7 is assumed to be an extra internal port for installing dedicated custom ROM (again any ROM/RAMs can be plugged in that port in the emulator).


Note: all machines are using state files with extension e72 including the HP-71B+. State files for the HP-71B+ are not compatible with the regular emu71 state files e71.




Below are a few screenshots demonstrating the new capabilities of the HP-72S:



Full CAT display


New SHOW PORT display format


AT LAST full display of a complex number !


OF COURSE a much much more comfortable view of program code


... and much more ...




File download:


emu72_091.zip : Emu72 beta version 0.91

Files to be installed in the emu71 execution folder. Content:

emu72.exe : HP-72S emulator

real72sl.kml : KML script for the HP-72S large skin

real72sm.kml : KML script for the HP-72S medium skin

real74sl.kml : KML script for the HP-74S large skin

real72sm.bmp : HP-72S medium skin for 800x600

real72sl.bmp : HP-72S large skin for 1024x768

real74sl.bmp : HP-74S large skin for 1024x768


rom72s_3e7.zip : HP-72S ROM file

prototype version 3eeee (revision 7)


emu72pat091.zip : patched source files for emu72, to be used with the emu71 source files.






If you have more information on any projects related to HP-71B developments, or if you have bug reports or suggestions for improvement, please contact me:

J-F Garnier, 2021