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At the bottom

H.P. 41 C


by Jean-DanieL Dodin


Editions of Cagire

Limited liability company with the capital of 20000F

Rc Toulouse B 327 662 609

ISBN 2-86811

77 street of Cagire




Fourth re-examined and corrected edition

First quarter 1984

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I) Introduction


This book could not have been born without the existence of the club PPC (Personnal Programming Center) which gathers certainly the best specialists in the pocket calculators HP. The sum of knowledge that the club could accumulate on the HP-41 C is properly confusing. On the 6000 members of the club, many is those which added their contribution to construction. The principal workmen themselves are too numerous so that it is possible to quote them all. It will be necessary for me to be limited to the architects, that the others excuse me.


Initially Richard J Nelson (PPC nl) without whom nothing of all that could have existed. Founder of PPC and editor of PPC Newspaper, it is entitled to all my recognition. Then Bill Wickes of which the book on the synthetic programming opened the eyes to me on a new world. And still Paul Lind, brilliant decouvror of the instructions microcodes and John McGechie, coordinator of the Australian Chapter of PPC which first ensured the dissemination of knowledge on microcodes.


And so much of others still... John Dearing, Cary Reinstein, Robert Groom, Keith Jarett, Lynn vilkins.., thank you with all.


This book is a little particular. It includes/understands few programs and the majority among you will never have the occasion to use certain chapters. But after all I will never have the occasion to make the climbing of the Everest and I however took great pleasure to read the account of it. I hope that this work will bring as much from there to you.

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Chapter II, " Geography ", will give you a description of the structure of your HP-4, various zones which share the memory: as many drawers which can contain treasures.


Chapter III, " Significance of the figures ", will show you on which bases works the 4 and will allow you a better comprehension of the structure of the programs.


Chapter IV, " a particular zone ", analyzes the essential memory of the 4, that which defines all the remainder, that which is in theory its reserved field but which now is open for you.


The chapter V, " With the robber! ", will give for you a progress report on a particular method of construction of the artificial instructions which will enable you to simply solve the majority of the problems of synthetic programming and will give you some examples of application.


Chapter VI, " Microcodes ", will reveal for you the Holy of Holies, microcodes it. You will see the instructions usable and their operating mode.


Chapter VII, " Use ", finally, will give you sample codings Microcodes some, taken in your machine or realized by the author.


Finally appendices will try to answer the principal remaining questions.




Handling on the software, that it is normal, synthetic or microcodes some are without danger to the HP-4, worst which can arrive to you is a one night unavailability of your dear machine (cf V.5, p. 58).


It is not the same material handling which can bring the destruction of the central processing unit with a cost of repair of about 650 F (1983), this is why this type of handling is not described here.


The contents of this book in no way are guaranteed by Hewlett-Packard. Does the synthetic programming and microcode it are not in any way dealt with by HP You are adult, not? (in American NOMAS: Not To manufacture Supported: without support of manufacturing).


The author provides this information in good faith but does not accept any responsibility for any kind as for the use which can be made of it.

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Since the first edition, the author improved his hardware, which explains the best presentation of the current edition. THERE remain surely still errors, excuse it!




This edition was drawn with a small number of specimens This is deliberated, thus, it is possible from one edition to another to carry out the corrections required by the evolution of knowledge. Therefore the author will largely appreciate all the remarks which will be made to him and all corrections which will be announced to him.




This Book will not teach you all, and Far from there, of the programming of the 4, that it is normal or synthetic, nor even microcodes some. it is not its goal besides. It wants to be a basic working tool from which each one is Libre to work out its own applications. The best means of progressing is to exchange its knowledge with others it is the goal of club PPC and, particularly in what concerns us, of its French section.


Admittedly, much of things were already found, but of insulated rediscover them tous.les.jours and the sources are often foreign or inaccessible. If you appreciated this Book club PPC is made for you (addresses appendix III, p, 101).



This edition was deeply altered, but I made a point of preserving the numbers of pages as reference (these numbers are thus unchanged since the second edition, except for some annex). Blow certain pages are " Light " and other filled well., certain pages which were white were used for complements.

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