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My first HP-41 was sped up by about 40%

Did anyone here do speed-ups?

Does anyone remember how they were done, especially the ones that used reed relays to control the speed.

Does anyone want to write an article?

My first hp-41 was done by a guy here in Toronto, Simon
Hughes (I may have the spelling wrong). I don't know
whether he hangs out here, and I haven't seen him for
almost 20 years.

I think the instructions were from the PPC Journal, and
I believe just involved changing a capacitor to modify the
RC circuit timing.

The mod's worked perfectly, and it's about 40% faster.
There have never been any problems reading or writing cards
or on the HPIL loop, or the bar code reader. It is
interesting to see how much it compresses the information
on magnetic cards. (Someone used some kind of a ferrite
solution once to demonstrate, and the data on the cards
were compressed probably by about 40% too. But because
the timing information is encoded with the data, the
cards worked fine with other machines)

I have several CVs that run at 2.3x normal speed. Both came with aircraft balance and weight modules & overlays. I haven't tried them with any peripherals.

2.3 x normal? I didn't think that was possible!

One thing I forgot to mention was the distinctly higher
(and more pleasent in my opinion) pitch of the BEEP and
TONE functions.

Being a newbie student pilot, I'm curious about the modules
you mentioned. Are they for specific aircraft? And they
*only* do W&B? Curious.

Cheers.

They're for a C-9B. I haven't played with them much but the labels on the overlay are: CHANGE, REVIEW, CLEAR, SECO, BASIC, CREW, CRBG, STEW, EMERG, XTRA, FUEL, PAX, CARGO, OUTPUTS, +/-, LOAD, CORR, COMP, ALL, STATION, C-9B, W&B, CG, P-S, APAC, NO, YES.

The C-9B is the military version of the DC-9, often used for medevac missions.

Best,

--- Les [http://www.lesbell.com.au]

###### FROM PPC-T ##########

From: Philippe Montegnie <pmontegnie@o...>
Date: Mon Jul 10, 2000 11:43pm
Subject: HP41 Acceleration (description)

An english approximative translation is available at the end of this email.

Prologue : La manipulation decrite ci-dessous necessite de connaître un peu l'electronique. Si ce n'est pas votre cas, ne risquez pas inutilement d'alterer la santé de
votre machine.

Dans les anciens modèles de HP41, vous pouvez voir un condensateur de 150pF en face d'un condensateur de 470pF.

Il suffit de changer le condensateur de 150pF par un circuit comprenant en parallele deux condensateurs de 120pF et 33pF. L'utilisation d'un ILS vous permettra de
passer d'une vitesse à l'autre à l'aide d'un aimant fixé par exemple sur un des boitiers vides.

Schéma :
Avant:

A -----
|
|
--- 150pF
---
|
|
B -----

Après:
ILS
/
A -----------/ --------
| |
| |
--- 33pF --- 120pF
--- ---
| |
| |
B ---------------------

ILS fermé : 153pF vitesse normale
ILS ouvert : 33pF vitesse double

Le changement de vitesse doit se faire machine eteinte. Certains peripheriques ne suivront pas la nouvelle vitesse, d'où l'interêt de l'ILS pour revenir à une vitesse
normale.

P.S.: Testez votre machine en SIZE maximal en faisant par programme des RCL/STO sur tous les registres. Au besoin prenez un condensateur un peu plus grand que
33pF.

-------------------------------------------------------------------------------------------- English approximative translation

Preliminary : The manipulation described lower need some practice level in electronic. If it's not your case, dont take the risk to alterate the health of your pocket
computer.

In some older HP41 series, you can watch a 150pF condensator in front of a 470pF condensator.

You just need to replace the 150pF condensator by a circuit including in parallele deux condensator of 120pF and 33pF. The use of an ILS (french term for
"magnetic switch")will make you able to switch the two speed by using a magnet fixed for example on a empty module box.

Schéma :
Before:

A -----
|
|
--- 150pF
---
|
|
B -----

After:
ILS
/
A -----------/ --------
| |
| |
--- 33pF --- 120pF
--- ---
| |
| |
B ---------------------

ILS close : 153pF normal speed
ILS open : 33pF double speed

The speed switch must happen when the computer is turned off. Some peripherics will not accept the turbo speed, that's why the ILS make you able to get back a
normal speed.

P.S. : Test your machine in maximal SIZE with a program witch use RCL/STO functions on all registers. If needed, take a little bit grower condensator than 33pF.

Message 166 of 217

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Hello.

The McDonnell Douglas (now Boeing) C-9B is also known as Nightingale, and has been exported to two or three countries.

Regarding the military and the HP-41, in a book I found a picture of a US Army mortar crew. There were three people around the mortar, an officer and two soldiers. The officer had on his hand a strange box that looked like a rugged calculator, which drawed my attention.

The enclosure is thick, about time and a half the size of the standard 41, with a similar keyboard and display (namely with a gold shift key and Enter, which made me think it was a 41.) Ports are rugged too, and one of them has what appears to be an HP-IL cable.

I think this rugged device is some kind of military-type HP-41. Question is: if the HP-41 did find use with the US military, was any specialized model ever built? If so, was it similar to the rugged model of the book and what applications was it supposed to have? If such a model exists, would be a great addition to any collection (including mine.)

My impression is that the device was used as a firing trajectory calculation aid.

On the other hand, there's a couple of paintings by Ron Volstad that depict US infantrymen using a computer that looks like an HP-75. Was this model used by the US military (or by NATO) sometime around the early 1980s?

juan - i remember seeing something called the "41 battle case" in the educalc catalog in the mid 80's. it was something that nato used, but so could we if for instance you had a 41 and a cannon and that dam dog next door just wouldn't shut up at night. some surveyors bought them too. in fact, i think that i remember an ugly and pretty model, but that might be a 71 or 75 thing.
now it's my turn; have you ever seen a word processing program for a 41? mabye one that saves into extended and can print to a thinkjet?

From a 1986 EduCalc catalog.

db:

I worked on some refinements for the 41CX text editor but never went beyond that. Too much a project and too little time back then. Sorry.

Not a text editor, but in 1981 I wrote a cross-assembler that ran on my HP41 and output hexadecimal opcodes for the RCA 1802 COSMAC microprocessor. As far as I recall, it handled symbolic labels for addresses. Granted, the 1802 had a very simple instruction set, and the assembler did little more than converting mnemonics to hex values.

I should try to find the mag cards, otherwise no one may believe this!

I'd love to get that in the software library!

I don't know how many people would use it, but some things need to be saved there just to prove that people did things like that on calculators.

A friend of mine wrote a cross assembler for the Intel 8085 in 1988 on the HP-71B. I remember we used it in college. If interested I can try to dig it out somewhere.

juan; sounds like you took the same tack as i did. i never felt like mine was anywhere near finished either, though it did do something.

db:

It makes me feel fine to know that I was not the only one involved in such a project. It´s good to know that an idea you had was not that crazy after all.

We all did amazing stuff in our machines. Those were the days when memory was scarce and code had to be efficient, unlike today, when software becomes more and more complex just because we've got Intel and AMD round the corner to make faster microprocessors every six months.

You know, some things about those days weren't so bad. <g> When was the last time you heard someone call a program "elegant?"

Dave: thank you for the encouragement. I will be very busy in the following weeks, but will try to find it around mid january. Please do not expect a full working version, it was sort of a "for myself" thing.

Very interested! Would appreciate you digging it up.

Hello.

Yes, those days weren't so bad. No help files but a lot of forethought and instructions precisely entered.

When I started writing software for the 48GX, I noticed that algebraic expressions (those with ' ' delimiters) used up almost twice as much memory than stack keystroke-by-keystroke procedures in programs. So i ended up discarding algebraics and using "procedures." It even made program execution faster.

The code looks bigger and more complicated, but it's efficient -something I have to thank to the time spent with the trusty 41.

Dave:

I´ve got a four-point Lagrange interpolation program for the HP-41 that I'd like to donate to the software library. Is it possible? I had to think a bit about procedures when I wrote it, and came to my mind when discussing these code matters.

.

That's fine. I'm sure it will make an interesting example anyway.