HP-25 LP Calculator Panamatik’s New Low-Power Upgrade Kit Presented by: Jim Johnson HP Handheld Conference 2017 – Nashville, TN September 16-17, 2017

Problem: There are many HP Woodstock calculators that have suffered an electrical overstress due to AC charging with depleted batteries, faulty battery connector or no battery pack installed. The original ACT chip may be damaged, but the rest of the IC’s may be in good condition along with the high quality HP keyboard, LED display and case. Solution: Panamatik’s ACT Repair Kit and the NEW HP-25 LP (Low Power) kit! For purposes of this presentation, we will focus on the new HP-25 LP kit which incorporates Panamatik’s ACT chip.

A WORD OF Disclaimer: When using these instructions for repairing your calculator, or in any other case of using the new ACT for any purpose, you are aware, that you alone have the responsibility. Due to the limited availability of vintage calculators and their versatility, PANAMATIK was not able to predict any possible circumstances, which may occur. Therefore it does NOT take responsibility for any damage that can occur directly or indirectly from using these instructions or using the new ACT. We assure, that we tried to take care and took any precautions to provide you with all the information required for a successfully repair. Proceed only if you agree with these terms. PANAMATIK

HP-27 and HP-29C calculators. Introduction The “Woodstock Low Power” circuit is a replacement of the electronics for your Hewlett Packard “Woodstock” calculator like HP-21/HP-25. It takes over all functions and adds new ones. Like its older brother the “new ACT” circuit, it can repair your HP calculator if it should be damaged. But it is not meant to replace the “new ACT”, its main purpose is to give you the freedom of low current consumption and preserving your registers and the calculation state at any time. You don't have to switch off your LED calculator any more to save batteries. For converting your HP calculator into the LP version you normally just remove the two display driver chips, which are located below the LED display. Then you can place the new circuit inside. You don't have to unsolder all components from the original board, but you can if you like. While none of the old components are needed any longer, any repair will be possible. And as an unexpected bonus, the calculator will not longer surge battery power because the old switching power supply is disconnected. This unique feature gives the circuit its deserved name “Woodstock Low Power”. The “Woodstock Low Power” circuit applies to HP-21, HP-22, HP-25, HP-25C, HP-27 and HP-29C calculators.

For a great video on removal the ACT, see Geoff Quickfall’s HP-29C Integrated Circuits You will need to remove the cathode and anode display driver ICs and the ACT IC For a great video on removal the ACT, see Geoff Quickfall’s video “HHC2015: Woodstocks in the Twenty-First Century”

Main Goals of the LP Version “Woodstock LP“ circuit is a result of the idea to repair even those “Woodstock“ calculators that have a good ACT, but have damaged display driver chips or both, or a non-functioning power supply. Overcome the alphanumeric limits of the old HP display drivers Opportunity to add some new hardware More flash memory (512kByte flash memory) The PIC microcontroller Real Time Clock – very accurate (+/- 3ppm) Piezo beeper Low Power Can run up to 250 hours on 2500mA rechargeable NiMH batteries between charges 512KB Flash Memory Real-Time Clock/Calendar PIC Micro

What's new in “Woodstock LP” 1.) Ticker Text You can enter any text up to 80 characters, which will be shown as ticker text whenever you want. 2.) Show program step mnemonics Your program steps can be shown as mnemonics rather than as row column code. 3.) Real Time Clock The accurate RTC chip allows you to show the time, date, weekday and to set an alarm time. 4.) Show Battery Voltage You can show the actual battery voltage for monitoring the charge state. 5.) Show Temperature Not very accurate, but at least an approximation of the ambient temperature will be displayed. 6.) Sleep Mode Whenever no calculation is made, the calculator can enter sleep mode and doesn't consume battery power until waked up again. 7.) Beeper The integrated piezo beeper can be programmed to wake you up when a calculation is finished or the programmed alarm time matches the actual time. It can act as an alarm clock to wake you up!

What else is new in “Woodstock LP” ? 8.) Full Speed….all the time. Pause is one second. There is no original (slow) mode as in the previous ACT chip. 9.) Continuous memory Turned off….your registers and memory are preserved. Programs are stored in flash memory so they’ll stay preserved even with no battery installed! 10.) Flicker Suppression, Multitasking and detailed Memory Usage Display. (These are also included in the previous ACT IC) 11.) Emulates many Woodstocks! Just as with the original ACT, you can switch between the HP-25C, HP-29C, HP-34C and HP-67 12.) ROM Code “Show ROM Code” and “Show ROM checksum” are not longer part of the firmware. Because there are no external ROM chips connected showing their contents is obsolete. 13.) Stopwatch There is only one stopwatch counter available in the HP-25 LP, however, since it is controlled by the RTC chip, it is very accurate. Up to eight lap times. 14.) Chess Clock Function Removed This function was removed versus the original ACT IC due to only one stopwatch register availabile.

Even more….. “Woodstock LP” 15.) Maximum of 90 programs available in the HP-25 LP. Each program can hold up to 49 steps. Maximum of 88 registers available. 16.) Stopwatch can be run with the calculator in the “OFF” mode. SW can count down in sleep mode and wakeup automatically when it reaches zero. 17.) Wake Up To wake up the calculator just press the key. You can also configure your HP-25 LP to wake up by any key, if you set flag 13 by using Alternatively you can wake up the calculator with the ON/OFF switch. If you have entered Sleep Mode there are two events, which will wake up your calculator automatically - if the alarm time is activated and the time matches the alarm time - or if the stopwatch countdown timer is activated and reaches zero. In both cases the text “Alarm” appears in the display and the beeper will intermittently beep for about one minute. 18.) Many other existing ACT functions LED test, counts flash write cycles, improved show available memory register, 20 flags are available, show prog. checksum, etc.

And finally….. “Woodstock LP” 19.) Upload/Download Data The Low Power circuit can be connected to a PC via an USB/TTL serial converter. It is the same converter that is used for transferring updates to the new ACT chip. But now a firmware update can be made without needing to enter the bootloader at power up. It can be invoked from the normal running calculator at any time. And the PC connector is not only used for software updates, but can be used to upload your programs and register data from the calculator to the PC or download them in the other direction. The PC application for using all the communication features of the “Woodstock Low Power“ is in development.

Summary and Conclusions The HP-25 LP gives new life to the Woodstock LED series of calculators and adds new, desired features such as: Low Power and “always on” Fast execution speed Real-time clock/calendar/alarm/Stopwatch Program step mnemonics – full character set Continuous memory Larger memory (512KB of flash) State of battery and ambient temperature Can switch between HP-25C, HP-29C, HP-34C and HP-67 using overlays Fixes previously dead Woodstock calculators Optional IR/Printing and GPS module additions will be available It makes sound! “Beep!”

Acknowledgements and Credits Bernhard Emese (Panamatik) ACT and HP-25 LP development/Upgrade kits. Eric Smith – Original nonpareil pioneer development for HP calculators. Tony Duell (UK) – Information on MoHPC site and email exchange in 2012. Jacques Laporte – HP Calculator Forum (www.jacques-laporte.org/forum) email exchange and the papers “The ‘Woodstock’ generation”. Museum of HP Calculators – (http://hpmuseum.org) Geoff Quickfall – Numerous dialogues/information regarding HP calculators. Richard Nelson/HHC Conferences – All the archived information available on HP calculators. Personal Collection: HP01, HP10bII, HP12C, HP15CLE, HP17bII+, HP19C, HP21, HP25, HP29C, HP30b, HP32E, HP32SII, HP34C, HP35S, HP41CX, HP42S HP45, HP67, HP97, WP34S, HP Prime

ACT Manual Revisions Rev 1.00 Jan 25th 2015 initial release Rev 1.01 Feb 1st 2015 added welcome string and hexadecimal, octal conversion, schematic Rev 1.02 Feb 17th 2015 HP-27 added, new image of inserted ACT Rev 1.03 Apr 7th 2015 chapter for HP-21, HP-22, HP-27, HP-29C added Rev 1.04 May 17th Infrared printing added. Rev 1.05 Oct 21st HP-34E, HP-67E, Classics, ACT Flash Update added Rev 1.06 Nov 20th Vinyl Overlays added Rev 1.07 Mar 25th 2016 GPS added, Apr 17th, GPS program updated Rev 1.08 May 20th HP-01 added Rev 1.09 Dec 1st Flags 10-15 added, Continuous Memory saves also stack registers Rev 1.10 Jan 27th 2017 Program Overlay, load programs dynamically Rev 1.11 May 9th 2017 Placing the IR diode in HP-25 and HP-67 Rev 1.12 July 31st 2017 Multitasking, Flicker Suppression, Memory usage, Voltage, Temperature Rev 1.13 August 17th 2017 Woodstock Low Power page

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Thank you! © 2017 All rights reserved regarding the information contained in this presentation . Main presentation content is owned by Panamatik / Bernhard Emese If you have any questions you may contact Jim Johnson. Email: jjohnson873@yahoo.com