Message #1 Posted by Howard Owen on 26 Dec 2005, 11:56 p.m.
I haven't been able to put this little guy down for very long since I got it two weeks ago. This machine is just great! It fixes lots of things that were limiting and/or awkward of the 41C and adds some very nice extras of its own. In the first column are the full alphanumeric capability, easy access to functions, without typing and nearly ideal form factor. In the latter column are items like named variables, matricies with editor, complex numbers, built in solver and numeric integrator and graphics.
Now for the downside. It's such a pity that the 42S represents the high-water mark of keystroke programmable RPN calculators. The machine is full of promise for the future. The I/O is officially limited to printer output, though clever folks discovered you could dump raw memory, ROM and RAM, through the hidden memory editor, out the infrared port. It's still one way, though. The additional memory compared to the 41C is nice, but its tiny compared to other machines of the day. Once again,clever folks have designed a hardware hack to raise the memory to 32K. But then you have to fill it all up one keystroke at a time! The machine cries out for more RAM, and effective mass storage.
The CPU is slow. Nice new features like the alpha graphics are practically unusable for anything beyond small accents because of the speed. The system software isn't perfect either. The matrices are cool, but they are slow too. In an application I'm writing, I use alpha graphics to draw a screen. The graphics data is stored in a 5X7 matrix. The graphics are slow, but if I dump that data out to registers before I run the display update routine, it runs about twice as fast! So there's room for optimization there.
Some annoying limitations from the HP-41C are retained in the 42S. Registers are 56 bits, just like on the 41C, so they can only contain 6 alphanumeric characters. (6x8 = 48 bits + header byte). This make the alpha register size increase to 44 characters less helpful than it might otherwise be. The RPL machines showed the way to stacks and storage that could contain any type of data.
Taking all that into consideration, the 42S is still an awesome machine, all these many years later. HP has refused to release the 42S ROM into the public domain. I take a faint glimmer of hope from this that they might release a "43S" machine someday, with enhanced RAM and processor. Even if they did that in the same way they did the 33S, without changing the system software very much, it would still be a heck of a product. And perhaps some day something like OpenRPN will succeed to the point where it would be realistic to consider what an advanced keystroke programmable RPN machine based on current hardware technology would look like. When that happens, I hope the designers each have access to an HP-42S, to remind them of what the state of the art looked like at its zenith!