hp 28c
the screen is 23x4 characters and can accommodate limited graphing. the left keyboard provides character entry, making symbols a bit easier to work with compared to more recent models like the 48g. the supported data types are listed above the alpha keyboard and are:
it was the first model to make heavy use of soft menus. buttons like despite the powerful new system, hp had underestimated the memory requirement and to a large extent, the cpu requirement. the 28c has only 2k of ram. it was so small that it was impractical to store programmes in the machine because it needed most of the space itself for internal workspace. the 28c was quickly superseded by the 28s which is the same machine but with 32k of ram. ## symbolic featuressymbolic quadratic equations are treated specifically, yielding a symbolic
answer for both roots. eg any singly occurring variable can be isolated symbolically. various symbolic manipulations are offered manually, like expand and collect. symbolic differentiation with respect to a given variable. eg symbolic integration of polynomials. symbolic generation of taylor series approximation to an expression. unfortunately very limited in term length due to the small amount of available ram. ## other factoidsit was the first to support a wider numerical range. exponents of up to +/-499 can be accommodated. the real numbers are augmented by mod(1e400,9)=1. good answer. |