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1. BATTETIES FOR A HP 425 RPN SCIENTIFIC CALCULATOR MANUALS
2. BATTETIES FOR A HP 425 RPN SCIENTIFIC CALCULATOR MOD
3. BATTETIES FOR A HP 425 RPN SCIENTIFIC CALCULATOR PORTABLE

This is a very efficient way to compute these functions for processors that cannot multiply or divide quickly. The trig and log functions are computed using CORDIC routines. The size of numbers had to be shrunk to 120 places down from the original 255 so that all the buffers would fit in the microcontroller's 4k of RAM. This is much faster than the original RPN Scientific Calculator which used external RAM for buffers during calculations. The stack is stored on an external SPI SRAM but all calculations are done using the internal RAM of the microcontroller. The interface shows 4 levels of the stack, similar to some HP calculators. Keystroke programming with 10 user defined functions

BATTETIES FOR A HP 425 RPN SCIENTIFIC CALCULATOR MOD

Functions: (a)sin, (a)cos, (a)tan, y^x, x root y, e^x, ln, 10^x, log, mod Internal accuracy configurable from 6 to 32 decimal places It is smaller, faster, and uses less parts. It uses an LPC1114 microcontroller and adds keystroke programming. It occasionally goes BANG! rather loudly in the middle of the night.This is an improved version of the first RPN Scientific Calculator ( ) I made. My daughter has an illuminated llama toy which has them in it which suffers from the same thing. Current drain was pretty high so it'd finish off the sealed button cell batteries very quickly which would over-discharge and explode. One of Sinclair's most amazing products was a digital watch which exploded regularly.

BATTETIES FOR A HP 425 RPN SCIENTIFIC CALCULATOR MANUALS

That might explain why the first run of them was "problematic" I have considered creating a web site archiving information and manuals for British test gear manufacturers recently as a lot of this history is missing or fragmented. But it did indeed exist and had Sinclair at the top left instead of Thurlby. I think it had a VERY short run before the company was rebranded to Thurlby. I have only ever seen one in existence in the rotten test gear stores of Cossor, but yes there was an actual Sinclair branded power supply called the P元10 back in the day.

BATTETIES FOR A HP 425 RPN SCIENTIFIC CALCULATOR PORTABLE

In fact Thandar made a lot of test gear which stacked neatly: They even reused the CRT from Sinclair's failed NEB portable television effort to make a scope, the one pictured below I repaired a few years back: Now onto an interesting thing. Sinclair went in the direction of computing with Sinclair Research as did Chris Curry who had enough of his shit pretty damn quickly and started Acorn The company was renamed by NEB to Thandar Instruments. Clive Sinclair and Chris Curry (guy who founded Acorn and ARM) bailed out. No coincidence it looked like and shared a lot of parts with this equals button encrusted scum imposter calculator: Eventually they evolved into something usable-ish: About then they started developing something a few of us own today! Perhaps unsurprisingly being Clive, he buggered the company thoroughly, it got bought out by NEB (Labour's scheme to try and get large businesses under state control), who buggered it further, also unsurprising. He produced all the consumer crap you're all probably aware of but also developed some test gear. Sinclair Radionics was the main company in the late 1970's of Clive Sinclair, the slightly less competent Madman Muntz of the UK. Seeing as we're on Sinclair and I'm bored, some trivia for people.

There is a picture in the metrology subsection. Have you guys seen that Keysight has sent TiN a new 3458B.

Below more gratuitous HP LED prom, - serious Tek collection - again hope the floor is up to it - lovely collection - my first calculator that I bought with my money was a Sharp flourescent - it was good but the quality wasn't up there - chewed through batteries - it is still hard for me to get away from the impression I formed in those years that LCD and CFL displays are for 'cheap gear' - It is now rather amusing that my most expensive bit of kit (or close to it) is a CFL HP 3458A. The 55/85 etc were holding the beer till the 41C/CV etc came along. The 35 while it was the first and ground breaking but the 45 had the feel of "being sorted" and was a real bit of kit.

Quote from: VK5RC on January 10, 2020, 10:30:34 am I really think the 45 was HP's real breakthrough calculator.