HP-28
With HP-28C (from 1987) and HP-28S (from 1988) were two scientific calculator from Hewlett-Packard called. These are the forerunners of the HP-39G, HP-48 , HP-49 and HP-50 series.
The main features of the HP-28C / S include:
- A computer algebra system (CAS) was installed for the first time , which allows the use of algebraic expressions and symbolic operations such as the derivation of functions, Taylor expansions and simple integrations.
- Programming in Reverse Polish LISP (RPL).
- Calculations are made in the reverse Polish notation (UPN).
- Any number of stack registers that can accommodate any data types, expressions in symbolic algebra and programs.
- Complex arithmetic and matrix functions, also in combination with one another.
- High accuracy through BCD arithmetic .
In a calculator developed by HP and is NEC Electronics produced HP Saturn processor used.
HP has combined the design with a folding mechanism in which both parts of the case are given a freedom of movement that corresponds to that of a book with a spiral binding. When closed, the control elements of the computer are protected. The cover contains an additional alphanumeric keyboard (see picture, left half) and, when open, can lie next to the computer or can be folded completely behind the computer. In the latter position, the usual, purely numerical calculations can be carried out while the calculator is held in the hand like a single-width pocket calculator.
The memory capacity of the HP-28C is 2048 bytes and the CPU works with a processor clock of 640 kHz. This model was replaced about a year later by the 28S with 32 kiB permanent memory at 1 MHz, which in turn was on the market until 1992. In 1991, Hewlett-Packard launched the HP-48S, a competitor and successor to the HP-28S. Users found new possibilities for synthetic programming of the HP-28, a term that arose with the programming of the HP-41 and denotes the discovery and use of undocumented functions and registers.
As the forerunner of the HP-48 (which was first launched as the HP-48SX in 1990), the HP-28 is technically very similar. The main differences are:
- The 28 models are not expandable.
- The infrared interface only has a transmission function, but cannot receive any data. Data can be sent to the printer. In addition, programs / data can be sent to newer HP computers with a corresponding interface.
- Less storage capacity on the HP-28C compared to the HP-48SX.
- Smaller display with 137 × 32 pixels (4 lines), whereby the bottom line disappears when the names of the softkeys are displayed.
- No real-time clock (RTC) and alarm functions, only access to the internal clock counter.
- Lower working speed.
A disadvantage of this design is that it is considered irreparable in the event of defects due to the welded housing.
Web links
- hpcalc.org Very extensive (software) archive for HP pocket calculators
- hpmuseum.org Historical information on various HP pocket calculators (English)
- Paul Courbis, Sébastien Lalande: Voyage au center de la HP28c / s . Editions de la Règle á Calcul, Paris 1989 (French, courbis.fr ).
Individual evidence
- ↑ Additional literature: William C. Wickes ( DNB 110016408 ): HP-28 Insights - Principles and Programming of the HP28C / S . Larken Publications, Corvallis OR 05.1988
- ^ WAC Mier-Jedrzejowicz: Customize your HP-28 . Self-published, ISBN 0-9510733-1-1