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Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

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Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#51

Post by Zenst »

If you need to explain this too less geeky friends then telling them that this amount of storage is less than a single letter on a modern display. Which on a 32bit display at 12x12 you would be on 576 bytes (8 bits) and this is compared to a 320 11 bit word (320x11/8=440) 440 bytes.

This makes chess on a 1k zx81 including display seem like bloat-ware now :).

Nowadays we have more storage on the keyboard controller chips, heck the older ones during the 90's had 4 KB storage, so almost 10x more ROM alone to work with - for a keyboard.

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#52

Post by rarw »

eli wrote: post #14
rarw wrote: post #10

Reverse Polish Notation - sounds like the punch line to a really bad math joke

Allegedly the name "Polish Notation" stuck because nobody could pronounce its inventor's name: Jan Łukasiewicz

Poor guy. I wonder how many light bulbs he had to screw in before people learned his name.

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#53

Post by lutusp »

joezydeco wrote: post #49
lutusp wrote: post #45

Earlier quoted context omitted.

> Thank you for writing Apple Writer. You're welcome! I know this is a predictable remark, but I miss the good old days. The Apple II was so simple and understandable that I was able to write a program that played two musical notes at once (I called it the "Electric Duet"), in tune, and a fairly tolerable sound, even though the speaker was driven by a TTL output (meaning no analog level control). If the Apple II had…

And thank you for writing Electric Duet! That program inspired me to (cough) take it apart and understand how something so cool could come out of the Apple II's speaker. That exercise taught me 6502 opcodes and I've been working in embedded systems ever since.

Looking back, I realize I must have spent two weeks just writing the Electric Duet player, because the time through the player loop had to be constant. The loop read through the notes to be played, synthesized them, and changed their duty cycle, but had to use the exact same number of machine cycles regardless of what it did, so the music stayed in tune.

Near the end of the project, I had two problems: the music was slightly off-pitch -- middle A wasn't exactly 440 Hz -- and the number of machine cycles wasn't quite constant (it varied between 40 and 41 cycles depending on which branches the code took).

Finally I realized I could insert a single NOP (no-operation) instruction at a critical location. The NOP forced the number of cycles to be a constant, regardless of the path through the loop, and I then realized that it also slightly changed the output frequency to be tuned exactly right.

I will always remember that moment. :)

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#54

Post by abecedarius »

6ren wrote: post #20

Unfortunately, as calculator prices collapsed, so did Sinclair Radionics' profits, and the company was broken up in 1979 after heavy losses. He fought Moore's law, and the law won. But this whole thing reminds me of Woz's work in the first Apples. Why wasn't his genius work similarly wiped out? Soon after the Apple, there were dozens - hundreds - of new personal computer manufacturers. I think it's software. The valu…

Good point, how calculators differed from computers. Branding surely helped IBM establish the PC, but against Apple what mattered was its years-later entry to the 16-bit world, with a relatively closed system, with high margins. Apple had a shot at 16-bit dominance but missed. (They came out with the Apple 3 and Lisa first.)

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#55

Post by Zenst »

bolder88 wrote: post #50
kryptiskt wrote: post #32

Earlier quoted context omitted.

One unnamed reason for Sinclair Radionics' falling apart was their digital watch, Black Watch, which was the ultimate example of Sinclair's infamous cost cutting and lack of quality control. http://www.nvg.ntnu.no/sinclair/other/blackwatch.htm

Surely also ridiculous diversions such as the C5 electric car. "Micromen" is a fantastic drama of the period... http://www.youtube.com/watch?v=sIcAyFVK0gE

At the time of the C5 I worked for one of the then government owned utility companies which had shops selling the C5. Was able to get a staff discount but was told of of the 2 seater version with a roof that was planned for release and saw pictures and spec etc, so I waited.

Great idea, ahead of it's time engineering and attitude wise as well. Did not even have rare earth magnets, seen C5's with rare earth magnet motors instead of the stock motor and they are dangerously fast. Today we are slowly getting there, though cars still designed for everybody with a 4-5 member family with a boot of shopping all the time and the other end is a motorbike. Still a car/bike electric combinations do appear, albeit not mainstream and most put of from the safety of getting hit by others as you are smaller on the road effect. Which makes you think about the limitations of a vehicle that is surrounded by taller and larger ones, why we now start to believe in bike lanes. Which was a factor back then and why the C5 never kicked off enough to make the C10 and C15 go into production beyond the prototypes sadly and C5's started coming with a flag pole akin to a football/soccer corner post style pole and flag.

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#56

Post by beambot »

arbuge wrote: post #44
ck2 wrote: post #6

I am not sure what is more amazing, the original creation or the cleverness of the person who figured out everything they did. I guess the original creation but wow, now that is a dedicated hobbyist. The Visual 6502 group enjoys dissolving old chips in acid, photographing the die, and reverse-engineering them. Wow!

The Visual 6502 group enjoys dissolving old chips in acid, photographing the die, and reverse-engineering them. Unfortunately (or not, depending on your perspective) it's not just the Visual 6502 group that enjoys that. Any leading chip in the marketplace these days is almost immediately reverse engineered in this way. I haven't been in the chip business for a few years but I recall a company which offered this as a…

FlyLogic used to do some awesome teardowns too: http://www.flylogic.net/blog/

If you go back through their blog posts, they have some cool techniques for bypassing "security" metal meshes to read out the secure FLASH/ROM sections of chips.

IIRC, one of the guys behind FlyLogic was involved in the high-profile reverse engineering of satellite receivers (ie. satellite pirating).

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#57

Post by wowaname »

eli wrote: post #14
rarw wrote: post #10

Reverse Polish Notation - sounds like the punch line to a really bad math joke

Allegedly the name "Polish Notation" stuck because nobody could pronounce its inventor's name: Jan Łukasiewicz

I'm gonna make a wallpaper right now with his name on it.

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#58

Post by jordanthoms »

I really wish someone would make a modern scientific calculator - Imagine what would be possible on a modern ARM processor. Even the new HP calculators use old ~70mhz ARM processors emulating the even older saturn HP48 code...

You could build it on top of Android, and have the software be open-source while making money from selling the hardware (so you could run it on a touchscreen, but if you wanted a keyboard you'd buy the calculator).

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#59

Post by CamperBob2 »

lutusp wrote: post #27
WalterBright wrote: post #25

Earlier quoted context omitted.

VisiCalc on the Apple had a huge contribution to its success. It was the proverbial "killer app" that drove Apple II sales.

Yes, that and Apple Writer. Full disclosure: I wrote Apple Writer.

Apple Writer made me the writer I am today. (To this day, I rarely compose paragraphs more than a few dozen words long.)

Re: Reversing Sinclair's amazing 1974 calculator hack - half the ROM of the HP-35

#60

Post by arbuge »

pdknsk wrote: post #48
arbuge wrote: post #44

Earlier quoted context omitted.

The Visual 6502 group enjoys dissolving old chips in acid, photographing the die, and reverse-engineering them. Unfortunately (or not, depending on your perspective) it's not just the Visual 6502 group that enjoys that. Any leading chip in the marketplace these days is almost immediately reverse engineered in this way. I haven't been in the chip business for a few years but I recall a company which offered this as a…

http://www.chipworks.com/

Yeah, that's the one.
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