HP-15C CE: 1 or 2-byte instructions ?

[Pekis]

Hello,

On my HP-15C CE (Edited after Werner's comment: "in extended mode" ("15.2")) , the "RCL+ 1" instruction needs 1 byte instead of 2 (according to Owner's handbook, p. 218) ?

Is it an additional saving compared to the original HP-15C ?

Thanks

[Werner]

You must have a very special 15C CE, then ;-)
On mine, it takes 2 bytes.
Werner

[Pekis]

(08-24-2023 01:18 PM)Werner Wrote:  You must have a very special 15C CE, then ;-)
On mine, it takes 2 bytes.
Werner

I forgot to say that my HP-15C CE is in "extended mode" ("15.2")

Thanks

[f16falcona46]

Strange, if I have an empty program memory (except for RCL+ 1), g MEM shows 25 167 01-5. So I think it takes two bytes since 1 reg is 7 bytes. (I am in the unsupported 15.2 mode.)

[Werner]

So is mine (of course ;-)
It does not make a difference?
And it's really easy to check, so I don't know whether I am making some silly mistake, or you are ;-)
Werner

[Didier Lachieze]

(08-24-2023 01:09 PM)Pekis Wrote:  On my HP-15C CE (Edited after Werner's comment: "in extended mode" ("15.2")) , the "RCL+ 1" instruction needs 1 byte instead of 2 (according to Owner's handbook, p. 218) ?

Where do you see that the "RCL+ 1" instruction needs 1 byte instead of 2 in the Owner's handbook, p. 218?
On this page the "RCL+" instruction is listed in the Two-Bytes Program Instructions in the same way as in my original 15C manual.

[Pekis]

OK, my bad, I made a confusion between programming steps and actual memory

Thanks

[Werner]

No worries.. the 15C has some more confusing things,
eg. the use of RCL DIM I and RCL DIM (i) ought to have been the other way round.
(the manual itself is also confused about this, there's a typo on page 178, where it lists RCL DIM (i) where it should be RCL DIM I)
I is direct, (i) indirect.

10 STO I
then
RCL (i) will do a RCL 10

RCL MATRIX A STO I
then
RCL (i) does RCL A (recall element A(r,c), r=Reg0 and c=Reg1)
RCL DIM (i) should then give you the dimensions of A but alas, the instruction to do that is RCL DIM I, as DIM (i) is used for memory partitioning - but then they could easily have taken DIM I for that.
A bit strange for an otherwise so consistent machine.
Werner

[J-F Garnier]

(08-24-2023 01:40 PM)Didier Lachieze Wrote:  ... the Owner's handbook, p. 218
On this page the "RCL+" instruction is listed in the Two-Bytes Program Instructions in the same way as in my original 15C manual.

Note that the CE manual (correctly) adds the "GSB .label" to the list, which was missing in the LE and original manuals.

BTW, the left side of the list is using parentheses () for the parameter list, whereas the right side is using { } brackets. I don't see the logic.

J-F