HP-65 trivia
02-20-2015, 01:48 PM
Post: #1
 Don Shepherd Senior Member Posts: 745 Joined: Dec 2013
HP-65 trivia
The HP-65 does base conversions between decimal and octal only.

Convert octal 11 to decimal, and it becomes 9, of course.

What other number will also convert to decimal 9?
02-20-2015, 02:17 PM
Post: #2
 Gene Moderator Posts: 1,232 Joined: Dec 2013
RE: HP-65 trivia
In octal or another base?

10 base 9 does. (and yes a big :-) here!)

Hope you are doing well Don!
02-20-2015, 03:34 PM (This post was last modified: 02-20-2015 03:35 PM by Don Shepherd.)
Post: #3
 Don Shepherd Senior Member Posts: 745 Joined: Dec 2013
RE: HP-65 trivia
(02-20-2015 02:17 PM)Gene Wrote:  In octal or another base?

10 base 9 does. (and yes a big :-) here!)

Hope you are doing well Don!

Hey Gene, Nashville man, good to hear. It's cold up here in Looeyville, but I suppose it's the same in Nashville with this crazy winter weather.

If you do octal --> decimal on the HP-65, 11 gives 9. What other number would give 9 on an octal --> decimal conversion?
02-20-2015, 05:35 PM (This post was last modified: 02-20-2015 05:46 PM by Gerson W. Barbosa.)
Post: #4
 Gerson W. Barbosa Senior Member Posts: 1,452 Joined: Dec 2013
RE: HP-65 trivia
(02-20-2015 03:34 PM)Don Shepherd Wrote:  If you do octal --> decimal on the HP-65, 11 gives 9. What other number would give 9 on an octal --> decimal conversion?

9, per a special HP-65 "feature" you mentioned here a few years ago.

Gerson.
02-20-2015, 06:02 PM
Post: #5
 Don Shepherd Senior Member Posts: 745 Joined: Dec 2013
RE: HP-65 trivia
(02-20-2015 05:35 PM)Gerson W. Barbosa Wrote:
(02-20-2015 03:34 PM)Don Shepherd Wrote:  If you do octal --> decimal on the HP-65, 11 gives 9. What other number would give 9 on an octal --> decimal conversion?

9, per a special HP-65 "feature" you mentioned here a few years ago.

Gerson.

Yes, you remembered that Gerson. I still marvel over that "feature" and have wondered now and then how that happened.
02-20-2015, 06:52 PM
Post: #6
 Thomas Radtke Senior Member Posts: 778 Joined: Dec 2013
RE: HP-65 trivia
Can it be that simply there wasn't enough space left for an error handling?
02-20-2015, 06:56 PM
Post: #7
 Tugdual Senior Member Posts: 756 Joined: Dec 2013
RE: HP-65 trivia
Quote:As an additional feature, the "octal to decimal" conversion will accept non-octal arguments containing the digits 8 or 9. A non-octal number such as 998 will be interpreted as (9x82) + (9x8) + 8 = 656.
I would have expected 1220.

Seriously, this is a bit misleading, probably the reason why later on the 35s the use of a suffix like 'h' or 'o' was made mandatory to the detriment of a certain ease of use. I remember the prime was also quite painful. I wish I had had a 16c.
02-20-2015, 07:14 PM
Post: #8
 Don Shepherd Senior Member Posts: 745 Joined: Dec 2013
RE: HP-65 trivia
(02-20-2015 06:52 PM)Thomas Radtke Wrote:  Can it be that simply there wasn't enough space left for an error handling?

That's probably the most likely explanation, Thomas. The 65 has no alpha display capability, so normal error messages are not possible. Instead, the display blinks when an error such as divide by 0 or square root of a negative number occurs. It would have required more microcode to check an "octal" number for erroneous digits 8 or 9, and they probably just didn't have the space.

So they documented it and called it a "feature."
02-20-2015, 07:43 PM
Post: #9
 Tugdual Senior Member Posts: 756 Joined: Dec 2013
RE: HP-65 trivia
02-20-2015, 07:47 PM
Post: #10
 Massimo Gnerucci Senior Member Posts: 2,420 Joined: Dec 2013
RE: HP-65 trivia
(02-20-2015 06:56 PM)Tugdual Wrote:
Quote:As an additional feature, the "octal to decimal" conversion will accept non-octal arguments containing the digits 8 or 9. A non-octal number such as 998 will be interpreted as (9x82) + (9x8) + 8 = 656.
I would have expected 1220.

Seriously, this is a bit misleading, probably the reason why later on the 35s the use of a suffix like 'h' or 'o' was made mandatory to the detriment of a certain ease of use. I remember the prime was also quite painful. I wish I had had a 16c.

The 41C had the same OCT and DEC feature but, at least, handles exceptions and throws a DATA ERROR.

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
02-20-2015, 08:09 PM
Post: #11
 Thomas Klemm Senior Member Posts: 1,541 Joined: Dec 2013
RE: HP-65 trivia
(02-20-2015 06:56 PM)Tugdual Wrote:  I would have expected 1220.

How would you end up with this result?

998o
[f-1] [→OCT]
656d
[f] [→OCT]
1220o

Cheers
Thomas
02-20-2015, 08:15 PM
Post: #12
 Tugdual Senior Member Posts: 756 Joined: Dec 2013
RE: HP-65 trivia
(02-20-2015 08:09 PM)Thomas Klemm Wrote:  How would you end up with this result?

998o
[f-1] [→OCT]
656d
[f] [→OCT]
1220o
Oh so you mean the calculator is converting but doesn't actually have a different base system?
I would have expected
998o
ENTER↑
1220o
02-20-2015, 09:19 PM (This post was last modified: 02-20-2015 09:35 PM by Thomas Klemm.)
Post: #13
 Thomas Klemm Senior Member Posts: 1,541 Joined: Dec 2013
RE: HP-65 trivia
(02-20-2015 08:15 PM)Tugdual Wrote:  Oh so you mean the calculator is converting but doesn't actually have a different base system?

It's like using these two programs:

998
→DEC
→OCT

Code:
00 { 36-Byte Prgm }             00 { 35-Byte Prgm }   01>LBL "->DEC"                  01>LBL "->OCT"        02 STO 00                       02 STO 00             03 -2                           03 2                  04 X<>Y                         04 X<>Y               05>LBL 00                       05>LBL 00             06 8                            06 10                 07 X<>Y                         07 X<>Y               08 10                           08 8                  09 ÷                            09 ÷                  10 IP                           10 IP                 11 X=0?                         11 X=0?               12 GTO 01                       12 GTO 01             13 Rv                           13 Rv                 14 ×                            14 ×                  15 Rv                           15 Rv                 16 ×                            16 ×                  17 STO+ 00                      17 STO+ 00            18 Rv                           18 Rv                 19 GTO 00                       19 GTO 00             20>LBL 01                       20>LBL 01             21 RCL 00                       21 RCL 00             22 END                          22 END

Cheers
Thomas
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