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[FLISZT]

(02-12-2023 07:27 PM)C.Ret Wrote:  Hello everyone.

The list given by FLISZT is unfortunately incomplete, he omitted to indicate some new functions and other functions already existing on the HP-28C but modified on the HP-28S.

1. First, Bruno forgets to mention that the HP-28S have 16x more RAM than the HP-28C (respectively 32 kB versus only 2 kB).
2. On the HP-28S, there is an additional menu labeled MEMORY assigned to the [I] key. This menu adds all the instructions organizing the new user menu system in the form of a tree structured in sub-directories. It contains the instructions MEM MENU ORDER PATH HOME then VARS and CLUSR.
   
   The CLUSR, ORDER and PURGE instructions exist on the HP-28C but are modified on the HP-28S in order to be compatible with the management of directories and sub-directories of user menus.
   
   The new CRDIR, HOME, PATH, VARS instructions make it possible to create and navigate within the system of directories and sub-directories of the HP-28S. Something impossible on an HP-28C because of the narrowness of the available RAM and the unique user menu.
   
   As a corollary, the HP-28S have three additional error messages related to sub-directories handling: 12A-Directory Not Allowed, 12B Non-Empty Directory, and 006-Power Lost which are missing on an HP-28C.
   
   The HP-28S also provide a configurable menu (CUSTOM menu) that can be defined at any time directly or within the programs, which makes it possible to compose dynamic and interactive user interfaces using the MENU instruction which activate any of the predefined menus of the HP-28S or compose personalized menus.
3. As Bruno pointed out, the HP-28S bring new graphic instructions allowing image management as strings and programmed scanning with the new →LCD LCD→ and DGTIZ instructions. As a result, the binary instructions AND, OR, XOR and NOT are modified in order to allow bit by bit manipulation of two alphanumeric strings of the same size, i.e. pixel by pixel for strings (or sub-strings ) from the LCD→ instructions.
4. Few people know it, but the HP-28S extend list management and allow concatenation or chaining, automatic evaluation of a list given as an argument and finding the position of an element with the modified POS instruction which is no longer limited to character strings as Bruno explain it.
5. As mentioned, the HP-28S calculate combinations and permutations, using the COMB and PERM functions respectively.
6. Secondarily, the HP-28S provide two functions concerning printing: it print a capture of the display using the key sequence [ON]+[ L ] and it allow double-line printing by setting flag 47.
7. Finally, the HP-28S provide additional units for dimensionless plane and solid angles (arcmin, arcsec, degree, grad, radian and steradian), as well as photometric units including or not including steradians (Lumen, Lux, Phot, ootcandle ) (Candela, FootLambert, Lambert, Stib).

Well, I hope I didn't forget anything. I initially wanted to make a short & quick answer but it is missed.

Thank you for your attention and to TellyS for its excellent site and historical compilation.

Oops... I also forgot to say - and so did you - that the 28S processor is +56.25% faster than the 28C processor (640 kHz vs 1 MHz). Is it serious Doctor ?

Joking aside, I didn't mention the memory size of the HP-28S (32K bytes) because TellyS had already done so before my previous post.

Thanks to Eric Rechlin and his site, everyone can now do their own in-depth comparative study between all HP models.

My purpose was to be synthetic and not (fortunately!) to duplicate one or several manuals. Goal completed!