Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!swrinde!emory!att!cbnewsb!druhi!neal
From: neal@druhi.ATT.COM (Neal D. McBurnett)
Newsgroups: comp.sys.handhelds
Subject: Re: HP-48 Comparison Test
Summary: A few corrections
Keywords: HP-48SX, calculators, portable computers, handhelds, HP
Message-ID: <326@cbnewsb.ATT.COM>
Date: 12 Mar 90 01:25:59 GMT
References: <39230@apple.Apple.COM>
Sender: news@cbnewsb.ATT.COM
Reply-To: neal@druhi.ATT.COM
Distribution: comp.sys.handhelds,comp.sys.hp
Organization: AT&T Bell Laboratories, Denver
Lines: 54

In article <39230@apple.Apple.COM>, dan@Apple.COM (Dan Allen) writes:

Thanks for an excellent article, Dan!  I just have a few comments.

Re: the solver
> ..... but the 42S did add a nice touch: it shows 
> the convergence/divergence of guesses as it goes.  At first glance the 48SX 
> Solver omitted this handy feature, but it turns out a key press will enable 
> it.

The 28S has this feature also.

Re: calendar
> How does the 48SX fare?  Well, not too bad.  It has date arithmetic; it has 
> time arithmetic, and HMS conversions.  It has about an 8400 year calendar.

I assume you are referring to the fact that dates between 15 Oct 1582 and
31 Dec 9999 are valid.  I think it is a shame that they didn't put in code
to handle the Julian calendar which was used before that fateful date
of Gregorian calendar reform - it's not hard!  It would also be
useful to have accurate historical dates back before the year 1, although
this would require a modification to the numerical representation.

As a sidelight, the calculator says that the year 4000 will be a leap year,
but I think that it should not be (assuming that our civilization still
exists and hasn't yet adopted a more sane calendar, changed the orbit
of the earth, etc.).

>... [ other missing features include: ]
>     Lap timers (for splits like the 41 Time Module)
>     Time calibration (EXACT like the 75C/71B)
>     True appointment scheduling (like the 75C)
> 
> This last feature is very important.  What it means is that you cannot use the 
> 48SX to set appointments of the style, "first Friday of the month", "the 15th 
> of the month", or even birthdays.  You see, the 48SX only repeats by a fixed 
> number of seconds.  It does not know about months.  Yes, it can schedule an 
> appointment every so many minutes, hours, days, or weeks, but not months, and 
> there lies the tragic flaw.

It would seem to be simple to define an exec function which would
reschedule the alarm for an arbitrary time in the future.  I look
forward to seeing or writing a general function for calculating the
next "first friday," etc.

What was the "EXACT" feature of the 75C/71B?

I also look forward to the gurus figuring out how to change the time
rate of the "date" and "time" functions.  So far mine seems to lose
about a half second a day.  I may have to revert to the hand-crafted
routines (based on the internal 8192-tick-per-second clock) I use on my
hp28S to get an accurate time (e.g. for timing occultations of stars).

-Neal McBurnett, neal@druhi.att.com