71 & 75 Math ROMs, Series 80 Matrix ROM

[J-F Garnier]

(05-28-2018 08:28 PM)Valentin Albillo Wrote:  I understand that this is only the first draft of it, because you've left out anything other than matrix-related functionality, and there are many (and big) differences re the rest of the function set.

Yes it is.

Quote:In the case of the 71B this is particularly noticeable because it's 5 times slower that the 75C to begin with, and it's CPU and OS are optimized for number crunching, not for branching or looping.

We can argue on the speed difference (it is not always that much, see here).
And I would not say that the 71's CPU (Saturn) is not optimized for branching or looping. There is no major difference here.
The biggest difference is related to the memory access. The 75's Capricorn CPU has many addressing modes (indexed, indirect or a combination, pre/post pointer increment, multiple stacks) and every register pair can be used as a pointer to the memory.
On the other side the 71's Saturn CPU has only two memory pointers (DAT0 and DAT1) and no other addressing mode than basic reading/writing to the pointed memory (à la HP41). And doing arithmetic on the pointers is tedious, requiring the use of a register and so a lot of operations. It's a big limitation.

Quote:Also, you don't include as an important feature that the Series 80 Matrix ROM allows for the creation and handling of matrices having 0 rows and/or 0 columns without giving any errors. This allows for straightforward generalizations in many sophisticated algorithms without having to consider and code especial cases. Neither the 71B nor the 75C Math ROMs implement this.

Thanks for pointing that feature, I didn't know it. It is indeed described on pages 46/47 of the Matrix ROM manual. Reading the example makes me think that this feature can produce quite obscure code sequences, so I'm not sure to regret it was not kept in the 71 & 75 :-).

Quote:

Quote:Finally, the 71 only implements a basic matrix operation set.

How true and how sad. They could have implemented most of the fuller set using those 5 Kb left to waste [etc...]

Well, at the light of the information I found above, I revised my judgement: yes the 71 matrix functions are limited to the basic, most useful set but benefit of a good implementation (speed optimisation).
Rather than the unused 5kB space, what I regretted at the time was that the Math ROM has not been used in certain application ROMs such as the Circuit Analysis pac that coded the matrix solving operations ... in Basic !

J-F