SR-52->HP-67 Keycodes efficiency

[Dieter]

(12-23-2017 08:32 PM)Matt Agajanian Wrote:  Ah! I see your point. If I understand you correctly, for TI to implement merged codes, more memory would be consumed, thus again limiting the program step/memory register count. Good point!

If one program step would consume one, two or three bytes the standard TI59 memory allocation (60 registers, 480 lines) would mean 480 bytes and thus only 160 lines in the worst case. Or typically maybe 250, as I wrote in my first post.

I'm not sure if advertizing a program memory of "up to 960 bytes" (and zero registers in the small print ;-)) would have been a good idea in 1977. The typical user might have asked how this translates to a familiar number of program lines, and this number might have been as low as 480 or 320. As far as I know the HP41 was the first calculator where a number of bytes instead of lines was published (max. 2237 bytes, up to ~2000 lines).

All this implies that lines with different byte counts would have been possible, technically. If, on the other hand, each and every step required the same two or three bytes the available program memory indeed would have been down to a fixed maximum of 480 or 320 lines. With not a single data register, that is. ;-)

And so finally we get to a familiar topic again: how many TI steps are equivalent to one HP step. #-) The usual result is a ratio near 1:1,8. So if you set a TI58/59 to 30 data registers (comparable to the HP67/97) and you get 240 or 720 program lines, this is roughly comparable to 130 or 400 HP-steps. Which confirms that HPs two calculators in most cases had more ressources than a TI58 but less than a TI59.

Dieter