Talk:HP-28 series

Please check whether there is any evidence of HP graphing calculators having fire problems. Probably vandalism? CHE 06:40, 29 July 2006 (UTC)

I suggest "HP-28s" is changed to "HP-28C/S". Alternative: "The HP-28 series consists of two graphing calculators produced by Hewlett-Packard from 1987 to 1992." 216.111.97.126 19:19, 30 August 2006 (UTC)

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What is the source of the 1987 introduction date? I have an HP-28S and it is from 1986. In fact, on the back it says "(C) HEWLETT-PACKARD CO. 1986".

www.HPmuseum.org. Which claims that the HP-28C was introduced in 1986, and the S one year later. Copyright notice doesn't mean anything: it could well be the copyright notice for the HP-28 family, and it would be for the copyright date anyway, not the date the calculator was sold or manufactured. Not that I know that HPmuseum has any better information than you do. —Preceding unsigned comment added by 203.206.162.148 (talk) 09:27, 25 May 2010 (UTC)

The serial number gives the answer : add 1960 to the first 2 digits - see Paul Courbis's books [1] Apc005 (talk) 15:40, 25 May 2010 (UTC)

Vague claim in article

What does "solving equations symbolically" mean? Before the HP-28, there were calculators that used variables (symbols that represented values unknown before calculations began). In this case, the claim must mean something entirely different or it is clearly wrong. -- kainaw™ 04:34, 19 April 2010 (UTC)

The HP-28 could solve equations where the variables represented values that were unknown before, during and after calculation. That is, it could do simple symbolic math. It could do this because it was a Lisp-based programming environment, not just a 'calculator'. I don't know that I would call this "solving equations", although I think that's what most students used it for. —Preceding unsigned comment added by 203.206.162.148 (talk) 09:22, 25 May 2010 (UTC)

"Drawback" of no computer interface

Just curious... was it at all common for a calculator in 1987 to have a computer interface? I ask because the article suggests that it was a "drawback" that the 28 didn't have one. --Ds13 (talk) 06:17, 9 November 2011 (UTC)

Sharp PC1211 (1980) & PC1500 (1892) had a tape reader interface, the HP71 and the HP41 had an IL interface if I remember correctly. The main problem of the 28 was the impossiblity to backup data. Event the TI59 was able to ! Apc005 (talk) 16:44, 15 November 2011 (UTC)

Complex number and matrix numeric

I think this article can be extended also describing HP-28s was able to handle complex number and numeric matrix calculation. It was (relative) simple also to extend it, with user programs, to make it handling symbolic matrix calculation. Thanks and sorry for my bad english.151.66.133.210 (talk) 00:42, 24 January 2012 (UTC)