Recall Arithmetic: The haves and havenots

05232015, 10:10 PM
(This post was last modified: 05232015 10:42 PM by Dave Britten.)
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Recall Arithmetic: The haves and havenots
You don't really come to appreciate recall arithmetic (RCL+, RCL, etc.) until you have to write programs for a machine that doesn't have it. I learned that pretty quickly last week with the 41CV. Sometimes avoiding that one stack lift can make all the difference.
Out of curiosity/boredom, I went through the comparison tool on this site eight models at a time to see which have it and which don't. I was going to make two lists, the haves and havenots, but it turns out so few models have the feature, that it's hardly worth listing the ones that don't. Have recall arithmetic: 15C (including LE) 27 32S 32SII 42S 45 46 WP34S The RPL models don't really need it, since they don't need to worry about stack overflow. Can anybody confirm that the 33S, 35S, and WP34S have recall arithmetic? I'm pretty sure they all do, but can't remember for certain. Anything else missing? 

05232015, 10:37 PM
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RE: Recall Arithmetic: The haves and havenots
The WP34S has.
 Pauli 

05232015, 10:42 PM
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RE: Recall Arithmetic: The haves and havenots  
05232015, 11:20 PM
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RE: Recall Arithmetic: The haves and havenots
(05232015 10:10 PM)Dave Britten Wrote: Anything else missing? The 9815 can do recall register arithmetic but only using register 000. This is pretty weird in that the reference to 000 is implied. So, 5 STO 000, CLEAR, 3 RCL x will result in 15. katie 

05232015, 11:36 PM
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RE: Recall Arithmetic: The haves and havenots
(05232015 10:10 PM)Dave Britten Wrote: You don't really come to appreciate recall arithmetic (RCL+, RCL, etc.) until you have to write programs for a machine that doesn't have it. I learned that pretty quickly last week with the 41CV. Sometimes avoiding that one stack lift can make all the difference. You can get it on the 41 now too, with Ángel Martin's new Total Rekall module. http://hpmuseum.org/forum/thread3738.html http://WilsonMinesCo.com (Lots of HP41 links at the bottom of the links page, http://wilsonminesco.com/links.html ) 

05242015, 12:22 AM
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RE: Recall Arithmetic: The haves and havenots
The 33S and 35S also have recall arithmetic.


05242015, 01:14 AM
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RE: Recall Arithmetic: The haves and havenots
It is interesting, that the non programmables HP45, HP27 does have recall arithmetics, and the programmables HP55,HP65,HP97,HP25,HP29C don't have it.
The reason for it is, that the necessary one byte opcodes for program steps were not available. RAM space was very precious and program steps were coded as one byte to get a maximum of 98 steps (HP29C) or 224 steps (HP97) from the RAM chips. The storage arithmetics in HP29C needs 64 opcodes of 256 possible, and the recall arithmetics would have needed another 64 opcodes, which were not there. see the list of program step opcodes http://panamatik.de/ProgramCodes.pdf. The later generation programmables HP32S, HP42S used at least >8 bit opcodes to solve this problem. Bernhard That's one small step for a man  one giant leap for mankind. 

05242015, 01:27 AM
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RE: Recall Arithmetic: The haves and havenots
The 25 has the opcode space for recall arithmetic.
Pauli 

05242015, 02:25 AM
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RE: Recall Arithmetic: The haves and havenots
(05242015 01:27 AM)Paul Dale Wrote: The 25 has the opcode space for recall arithmetic. It does have the space, but I wonder if the way instructions are decoded and executed limited them. Note how all the GTO and STO instructions tend to be aligned in such a way that looks like it was intended to ease decoding the address. Perhaps there wasn't enough ROM space to handle more complex address decoding for recalls, or just not enough ROM space to handle any recall arithmetic period. If it's an alignment issue, one has to wonder why they wouldn't have just moved other instructions around, though. Anybody have any insights into this from looking at a 25 ROM disassembly? 

05242015, 08:40 AM
(This post was last modified: 05242015 09:29 PM by PANAMATIK.)
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RE: Recall Arithmetic: The haves and havenots
(05242015 01:27 AM)Paul Dale Wrote: The 25 has the opcode space for recall arithmetic. I agree. It could have been used 0x800x87, 0x8D0xFD, 0x8E0xFE, 0x8F0xFF (05242015 02:25 AM)Dave Britten Wrote: If it's an alignment issue, one has to wonder why they wouldn't have just moved other instructions around, though. Anybody have any insights into this from looking at a 25 ROM disassembly? Yes, the HP25 disassembly shows, that the 2k ROM is fully occupied and size optimized as far as possible. The program step opcode decoding uses indirectly addressed jump tables called by the a> rom address instruction. Code:
As an example see the jump tables located at 02000: ff. 2000: decodes 0xF00xFF 2020: decodes 0xE00xEF 2040: decodes 0xD00xDF As you can see the opcodes 0xED,0xEF, 0xDD0xDF are not decoded but were used for go to destinations of other opcodes ( qenter: 1/x: ). Code:
Besides executing the recall arithmetic, there would have been needed 4 more jump tables and better decoding. I'm sure they were thinking about it and couldn't get the ROM space. Bernhard That's one small step for a man  one giant leap for mankind. 

05242015, 08:45 AM
(This post was last modified: 05242015 08:55 AM by Ángel Martin.)
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RE: Recall Arithmetic: The haves and havenots
(05232015 11:36 PM)Garth Wilson Wrote:(05232015 10:10 PM)Dave Britten Wrote: You don't really come to appreciate recall arithmetic (RCL+, RCL, etc.) until you have to write programs for a machine that doesn't have it. I learned that pretty quickly last week with the 41CV. Sometimes avoiding that one stack lift can make all the difference. I was going to say that but Garth beat me ;) Yes the Total_Rekall_2015 removed that thorn in the side  finally the 41 is within the "haves" group. And sure it does make a difference sometimes when the stack is fully used up. BTW it also adds RCL^ to the list of arithmetic operations  perhaps the only one out there. Cheers, 'AM 

05242015, 09:12 AM
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RE: Recall Arithmetic: The haves and havenots  
05242015, 12:14 PM
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RE: Recall Arithmetic: The haves and havenots  
05242015, 07:59 PM
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RE: Recall Arithmetic: The haves and havenots
(05242015 01:14 AM)PANAMATIK Wrote: It is interesting, that the non programmables HP45, HP27 does have recall arithmetics, and the programmables HP55,HP65,HP97,HP25,HP29C don't have it. Thanks, Bernhard, for explaining this. I had long wondered why such a useful function was not included on the early programmables. It is probably the same reason that storage arithmetic is limited to the first few registers on some financials, like the 12C. Thanks, Bob 

05242015, 08:52 PM
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RE: Recall Arithmetic: The haves and havenots
(05242015 07:59 PM)bshoring Wrote: It is probably the same reason that storage arithmetic is limited to the first few registers on some financials, like the 12C. This is not a special feature of the financial calculations, it's the same on several scientifics. For instance, on the 34C storage arithmetics is limited to registers 0...9, while it is not available on registers ,0...,9 and the I register. Then think of the 67 and 97: storage arithmetics is limited to the first ten registers. Accessing the next ten (even simple STO and RCL) requires switching via P<>S. The remaining six registers A–E and I also do not support storage arithmetics. Dieter 

06192015, 05:23 PM
(This post was last modified: 06192015 05:24 PM by PANAMATIK.)
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RE: Recall Arithmetic: The haves and havenots
(05242015 08:52 PM)Dieter Wrote: .... on the 34C storage arithmetics is limited to registers 0...9, while it is not available on registers ,0...,9 and the I register..... Today I was able to add the HP34C opcode table to my ProgramCodes.pdf document. You can see that the HP34C uses up all 256 possible opcodes except one for coding its program steps. The engineers choose carefully which are the most important functions. The SOLVE and Integral function uses only 6 of 12 labels. And as already mentioned, storage arithmetic can be done only with the ten primary registers. The most interesting part is to see, that f SCI 8,9 and f ENG 8,9 are not programmable. Only SCI 07 and ENG 07 are present, because the table would have overflown. If you try to program one of these display formats, it will be replaced by SCI 7 ENG 7, which is also mentioned in the manual. The more important f FIX 09 however is fully programmable. Even with the reduced registers 09, storage arithmetic uses 44 of 255 opcodes. Recall arithmetic would have needed another 44 opcodes. Due to this space limitation, the HP34C was probably the last and ultimate model, which used the one byte program step coding. I'm not sure whether the voyager models had already two bytes. Does anybody know? Bernhard That's one small step for a man  one giant leap for mankind. 

06192015, 06:09 PM
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RE: Recall Arithmetic: The haves and havenots
I never noticed the 34C or 15C recall arithmetic until I started using the 42S and started writing really long or complex programs. I was surprised a few years back when I discovered the 15C has it.
It really is the icing on the cake for RPN. And it's hard to do without it once you begin to use it. What's strange is the 15C has it, 41C doesn't, and the 42S does. 

06192015, 06:29 PM
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RE: Recall Arithmetic: The haves and havenots
(06192015 06:09 PM)Dwight Sturrock Wrote: I never noticed the 34C or 15C recall arithmetic until I started using the 42S and started writing really long or complex programs. I was surprised a few years back when I discovered the 15C has it. The 15C came after the 41C, and had a few features the 41 didn't. Matrices, solver, integration, etc. The Advantage module adds a lot of 15C features (and some from the 16C and 12C), but recall arithmetic isn't one of them. Fortunately, you can emulate it easily enough. RCL n becomes X<> n, STO n, X<> n. I think that would work with indirect addressing, too; don't have my 41 with me at the moment to test. (Which models do indirect recall arithmetic? Probably the 42S at least, I would imagine, and the 32S family via (i).) 

06192015, 07:23 PM
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RE: Recall Arithmetic: The haves and havenots
(06192015 06:29 PM)Dave Britten Wrote: (Which models do indirect recall arithmetic? Probably the 42S at least, I would imagine, and the 32S family via (i).) Not a genuine HP, but the WP 34S does it. Marcus von Cube Wehrheim, Germany http://www.mvcsys.de http://wp34s.sf.net http://mvcsys.de/doc/basiccompare.html 

05222019, 09:33 AM
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RE: Recall Arithmetic: The haves and havenots
(05242015 01:14 AM)PANAMATIK Wrote: It is interesting, that the non programmables HP45, HP27 does have recall arithmetics, and the programmables HP55,HP65,HP97,HP25,HP29C don't have it. Can’t really buy that explanation for the 65. Storage arithmetic is not merged so it would not be odd to have recall arithmetic unmerged. 

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