HP-28

The HP-28C and HP-28S are graphic computers developed by Hewlett Packard and distributed of 1987 to 1992.

The HP-28 was the first computer able to solve equations in manner symbolic system. It was replaced by the range HP-48 which is an extension of the HP-28.

One of the originalities of the HP-28 was its design: a double keyboard, alphabetical on the left, traditional on the right, which, while being folded up, protected the computer which, so did not need cover.

Posting was consisted a monochromic screen LCD of 137 pixel out of 32, allowing the posting of 4 lines of text (more the menu of the function keys), which allowed in particular the posting of the first 4 stages of the pile of calculation.

Two models were produced, the HP-28C appeared in 1987 with 2 KB of memory RAM (which one could extend by grafting a module report of HP-71 on the mother chart). One year later, the HP-28S was born, with 32 KB of memory and a system of repertories allowing the classification of the programs and variables.

The HP-28C was based on a microprocessor Saturn, 4 bits, to 640 Khz (which it was possible to accelerate at the price of a modification of the electronic circuit). The HP-28S as for it was based on improved Saturn with 2 MHz. Material acceleration was not possible any more, but a software acceleration existed.

One of the large defect of the HP-28 was the absence of connection with a microcomputer (although obviously envisaged in the hardware). the entered data could not thus be safeguarded and owed, in theory, being entered manually.

Its memory important making it possible to store quantities large of information, it was one of the first computers used like antisèche by the students.

The official computer programming language was the RPL (Romanian-based Procedural Language or Reverse Polish Lisp), but it was also possible to reach the machine language.

See too

  • graphic Computers
  • the HP-48, evolution of the HP-28

External bonds

  • Paul Courbis and Sebastien Lalande (1988), - files pdf.

  • the HP-28 on the HP Calculator Museum
  • Photographs of the HP-28S on MyCalcDB

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