1. 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

2. 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.

3. 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

4. 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.

5. 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”

6. 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

7. 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!

8. 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.

9. 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.

10. 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.

11. 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!”

12. 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 exchange in 2012.
Jacques Laporte – HP Calculator Forum ( exchange and the papers “The ‘Woodstock’ generation”.
Museum of HP Calculators – (
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

13. 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 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

14. APPENDIX

19. 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.