ENG mode, n+1?

[walter b]

(01-17-2014 08:05 PM)Dieter Wrote:  Could someone with a "real" HP-25 please check how it works in ENG mode? Until then I assume it behaves as described in HP Journal, i.e. in the same way as at least most other HP calculators. The authors of the mentioned article did the microprogramming, so they should know how everything is supposed to work.

HP25 owners: now it's up to you.

Not only up to them In fact, the turning point is between the HP-27 and the HP-29C, as you can find out easily leaving the forum and visiting the museum exhibition instead. HP-25 and -27 feature ENG with n+3, HP-29C and all models thereafter feature n+1. Just RTFM Coffee and cupcakes at the forum café are not everything.

d:->

[Sylvain Cote]

Here is what I see on my calculators ...

Code:


+---------------------------------------+---------------------------------------+---------------------------------------+
| HP-21      (D=DSP=SCI)     123.456789 | HP-25                      123.456789 | HP-27                      123.456789 |
| [E0: n/a         ] [D0: 1.       E02] | [E0: 123.     E00] [S0: 1.       E02] | [E0: 123.     E00] [S0: 1.       E02] |
| [E1: n/a         ] [D1: 1.2      E02] | [E1: 123.5    E00] [S1: 1.2      E02] | [E1: 123.5    E00] [S1: 1.2      E02] |
| [E2: n/a         ] [D2: 1.23     E02] | [E2: 123.46   E00] [S2: 1.23     E02] | [E2: 123.46   E00] [S2: 1.23     E02] |
| [E3: n/a         ] [D3: 1.235    E02] | [E3: 123.457  E00] [S3: 1.235    E02] | [E3: 123.457  E00] [S3: 1.235    E02] |
| [E4: n/a         ] [D4: 1.2346   E02] | [E4: 123.4568 E00] [S4: 1.2346   E02] | [E4: 123.4568 E00] [S4: 1.2346   E02] |
+---------------------------------------+---------------------------------------+---------------------------------------+

Code:


+---------------------------------------+---------------------------------------+---------------------------------------+
| HP-25C                     123.456789 | HP-29C                     123.456789 | HP-19C                     123.456789 |
| [E0: 123.     E00] [S0: 1.       E02] | [E0: 100.     E00] [S0: 1.       E02] | [E0: 100.     E00] [S0: 1.       E02] |
| [E1: 123.5    E00] [S1: 1.2      E02] | [E1: 120.     E00] [S1: 1.2      E02] | [E1: 120.     E00] [S1: 1.2      E02] |
| [E2: 123.46   E00] [S2: 1.23     E02] | [E2: 123.     E00] [S2: 1.23     E02] | [E2: 123.     E00] [S2: 1.23     E02] |
| [E3: 123.457  E00] [S3: 1.235    E02] | [E3: 123.5    E00] [S3: 1.235    E02] | [E3: 123.5    E00] [S3: 1.235    E02] |
| [E4: 123.4568 E00] [S4: 1.2346   E02] | [E4: 123.46   E00] [S4: 1.2346   E02] | [E4: 123.46   E00] [S4: 1.2346   E02] |
+---------------------------------------+---------------------------------------+---------------------------------------+

Best regards,
Sylvain
PS: if you need more tests let me known, I have all the models.

[Thomas Klemm]

(01-18-2014 02:19 AM)Sylvain Cote Wrote:  PS: if you need more tests let me known, I have all the models.

What might be interesting is to compare HP-25, HP-29 in ENG n mode with a later model (say HP-32E) in ENG n+2 mode. Display the numbers 1.23456789, 12.3456789, 123.456789, ...
It's interesting to see what happens with the HP-32E in ENG 0 and ENG 1 mode: the amount of digits in the display change when 1.23456789 is multiplied by 10, 100, ...

ENG 0

Code:


1.23456789: [1.       00]
12.3456789: [10.      00]
123.456789: [100.     00]
1234.56789: [1.       03]

ENG 1

Code:


1.23456789: [1.2      00]
12.3456789: [12.      00]
123.456789: [120.     00]
1234.56789: [1.2      03]

This doesn't happen when \(n\geqslant2\):

ENG 2

Code:


1.23456789: [1.23     00]
12.3456789: [12.3     00]
123.456789: [123.     00]
1234.56789: [1.23     03]

Only the decimal point gets shifted around. Thus the complicated cases of the ENG display format are avoided in the HP-25.

(01-17-2014 03:05 AM)Thomas Klemm Wrote:  But still sounds arbitrary. Why "after the first three"?

Maybe there wasn't enough place in the ROM to implement the special cases.

Cheers
Thomas

[Sylvain Cote]

OK, here is a new set of tests ...

Code:

ENG +--- HP-25  ---+ HP-29C [ 1.23456789] HP-32E +--- HP-41C ---+---- HP-71B ----+---- WP-34S ----+ ENG +[n4]+[n7]
0 :  [1.23      00] [1.        00] [1.        00] [1.        00] [1.E0          ] [1.          00]  : 0  [03] [06]
1 :  [1.235     00] [1.2       00] [1.2       00] [1.2       00] [1.2E0         ] [1.2         00]  : 1  [03] [06]
2 :  [1.2346    00] [1.23      00] [1.23      00] [1.23      00] [1.23E0        ] [1.23        00]  : 2  [03] [06]
3 :  [1.23457   00] [1.235     00] [1.235     00] [1.235     00] [1.235E0       ] [1.235       00]  : 3  [03] [06]
4 :  [1.234568  00] [1.2346    00] [1.2346    00] [1.2346    00] [1.2346E0      ] [1.2346      00]  : 4  [03] [06]
5 :  [1.2345679 00] [1.23457   00] [1.23457   00] [1.23457   00] [1.23457E0     ] [1.23457     00]  : 5  [03] [06]
6 :  [1.2345678 00] [1.234568  00] [1.234568  00] [1.234568  00] [1.234568E0    ] [1.234568    00]  : 6  [03] [06]
7 :  [1.2345678 00] [1.2345679 00] [1.234567  00] [1.2345679 00] [1.2345679E0   ] [1.2345679   00]  : 7  [03] [06]
8 :  [1.2345678 00] [1.2345678 00] [1.234567  00] [1.2345678 00] [1.23456789E0  ] [1.23456789  00]  : 8  [03] [06]
9 :  [1.2345678 00] [1.2345678 00] [1.234567  00] [1.2345678 00] [1.234567890E0 ] [1.234567890 00]  : 9  [03] [06]

Code:

ENG +--- HP-25  ---+ HP-29C [ 12.3456789] HP-32E +--- HP-41C ---+---- HP-71B ----+---- WP-34S ----+ ENG +[n5]+[n8]
0 :  [12.3      00] [10.       00] [10.       00] [10.       00] [10.E0         ] [10.         00]  : 0  [03] [06]
1 :  [12.35     00] [12.       00] [12.       00] [12.       00] [12.E0         ] [12.         00]  : 1  [03] [06]
2 :  [12.346    00] [12.3      00] [12.3      00] [12.3      00] [12.3E0        ] [12.3        00]  : 2  [03] [06]
3 :  [12.3457   00] [12.35     00] [12.35     00] [12.35     00] [12.35E0       ] [12.35       00]  : 3  [03] [06]
4 :  [12.34568  00] [12.346    00] [12.346    00] [12.346    00] [12.346E0      ] [12.346      00]  : 4  [03] [06]
5 :  [12.345679 00] [12.3457   00] [12.3457   00] [12.3457   00] [12.3457E0     ] [12.3457     00]  : 5  [03] [06]
6 :  [12.345678 00] [12.34568  00] [12.34568  00] [12.34568  00] [12.34568E0    ] [12.34568    00]  : 6  [03] [06]
7 :  [12.345678 00] [12.345679 00] [12.34567  00] [12.345679 00] [12.345679E0   ] [12.345679   00]  : 7  [03] [06]
8 :  [12.345678 00] [12.345678 00] [12.34567  00] [12.345678 00] [12.3456789E0  ] [12.3456789  00]  : 8  [03] [06]
9 :  [12.345678 00] [12.345678 00] [12.34567  00] [12.345678 00] [12.34567890E0 ] [12.34567890 00]  : 9  [03] [06]

Code:

ENG +--- HP-25  ---+ HP-29C [ 123.456789] HP-32E +--- HP-41C ---+---- HP-71B ----+---- WP-34S ----+ ENG +[n6]+[n9]+[ n0]
0 :  [123.      00] [100.      00] [100.      00] [100.      00] [100.E0        ] [100.        00]  : 0  [03] [06] [-03]
1 :  [123.5     00] [120.      00] [120.      00] [120.      00] [120.E0        ] [120.        00]  : 1  [03] [06] [-03]
2 :  [123.46    00] [123.      00] [123.      00] [123.      00] [123.E0        ] [123.        00]  : 2  [03] [06] [-03]
3 :  [123.457   00] [123.5     00] [123.5     00] [123.5     00] [123.5E0       ] [123.5       00]  : 3  [03] [06] [-03]
4 :  [123.4568  00] [123.46    00] [123.46    00] [123.46    00] [123.46E0      ] [123.46      00]  : 4  [03] [06] [-03]
5 :  [123.45679 00] [123.457   00] [123.457   00] [123.457   00] [123.457E0     ] [123.457     00]  : 5  [03] [06] [-03]
6 :  [123.45678 00] [123.4568  00] [123.4568  00] [123.4568  00] [123.4568E0    ] [123.4568    00]  : 6  [03] [06] [-03]
7 :  [123.45678 00] [123.45679 00] [123.4567  00] [123.45679 00] [123.45679E0   ] [123.45679   00]  : 7  [03] [06] [-03]
8 :  [123.45678 00] [123.45678 00] [123.4567  00] [123.45678 00] [123.456789E0  ] [123.456789  00]  : 8  [03] [06] [-03]
9 :  [123.45678 00] [123.45678 00] [123.4567  00] [123.45678 00] [123.4567890E0 ] [123.4567890 00]  : 9  [03] [06] [-03]

Code:

Notes:
[n0] -> same patterns for [.123456789] but with exponent -03
[n4] -> same patterns for [1234.56789] but with exponent  03
[n5] -> same patterns for [12345.6789] but with exponent  03
[n6] -> same patterns for [123456.789] but with exponent  03
[n7] -> same patterns for [1234567.89] but with exponent  06
[n8] -> same patterns for [12345678.9] but with exponent  06
[n9] -> same patterns for [123456789.] but with exponent  06

note 1: as walter pointed out, the HP-29C is the trigger point on how the eng mode was displayed.
note 2: the HP-3xE/C series has 1 digit less precision on the display
note 3: the HP-71B and the WP-34S are more precise

Best regards,

Sylvain

edit 1: formatting
edit 2: add HP-71B for completeness
edit 3: add notes
edit 4: add WP-34S

[Steve Simpkin]

Wow! As an Electrical Engineer I have used ENG mode in HP calculators A LOT over the past 36 years. I used my HP-25 for 10 years before moving on to newer HP models and never really paid close attention to the differences in ENG display mode. I typically used ENG 2 on my HP-25 to obtain 2 digits of precision beyond the 3 potential significant digits shown in ENG mode. This more or less mimicked the FIX 2 mode that the HP-25 defaulted to every time it was turned on. On later models I would use ENG 4 to achieve a similar display.
I am just glad I never used ENG 1 or ENG 0 on the newer models. Having 149 millivolts displayed as 100.E-3 or 150 milliamperes displayed as 200.E-3 is not good. I understand why it does this but I don't like it.

[Dieter]

(01-17-2014 09:26 PM)walter b Wrote:  Not only up to them In fact, the turning point is between the HP-27 and the HP-29C, as you can find out easily leaving the forum and visiting the museum exhibition instead.

Of course I checked the museum's HP25 page. The only reference to ENG mode I see is the sentence "Engineering display mode was also a first on this calculator". Where did you find further information and details, especially the n+3 rule in ENG mode?

Quote:Just RTFM Coffee and cupcakes at the forum café are not everything.

Walter, I do not own an HP25 and I also don't know a free source for its manual. So how should I RTFM? But that's not the point. I asked for results from a "real" HP25 because manuals are not always clear and unambigous, sometimes the information they give is even plain wrong. That's why I asked for results from an actual calculator. Many thanks to everyone who provided this information.

Dieter

[walter b]

(01-18-2014 06:25 PM)Dieter Wrote:  

(01-17-2014 09:26 PM)walter b Wrote:  Not only up to them In fact, the turning point is between the HP-27 and the HP-29C, as you can find out easily leaving the forum and visiting the museum exhibition instead.

Of course I checked the museum's HP25 page. The only reference to ENG mode I see is the sentence "Engineering display mode was also a first on this calculator". Where did you find further information and details, especially the n+3 rule in ENG mode?

Quote:Just RTFM Coffee and cupcakes at the forum café are not everything.

Walter, I do not own an HP25 and I also don't know a free source for its manual. So how should I RTFM? But that's not the point. I asked for results from a "real" HP25 because manuals are not always clear and unambigous, sometimes the information they give is even plain wrong.

Well, the (IMHO very modest) price for a lifetime (!) membership of "The Friends of the Museum of HP Calculators" is the DVD set, containing all the information you were looking for. Yes, even HP manuals are sometimes not perfect, but if you find the same facts in more than one manual you can be pretty sure that's the truth - in those times, HP quality was more than just a word. And you've seen the confirmation for that right now: the tests proved what's stated in the respective manuals as I've mentioned in my earlier post.

Anyway, all you need to do is becoming a member and then roam all the museum premises free of further charge. I recommend that way.

d:-)