HP-28S Quick Reference
See at the end of this document.
HP-28S Famous calculator made by Hewlett-Packard from 1988 – 1992.
Memory 32768 bytes for stack, programs and data.
Approximately 31.6 kBytes available to the user.
Press and hold ON then press + or – to change the contrast.
• 56 bit for real numbers, 12 decimal digits of precision, exponent
• 64 bit for binary numbers
The Stack The HP-28S is a stack-based calculator.
For details on using the stack see STACK Menu.
• Commands can be entered by typing their name explcitly.
• Most commands and functions are organized in menus, some are
directly available on the keyboard. See Direct Key Commands.
• SYSEVAL is the only command which neither accessible thru the
keyboard not thru a menu. See System Operations.
• Some commands are present in multiple menus.
See System Operations. Note that a program or other lengthy
operations can usually be interrupted by pressing "ON".
Can be turned off by clearing flag 51, see Flags.
HP-28C The main difference is the smaller memory of only 2 kByte.
And whereas the HP-28S comes with a software version "2BB" it is
"1BB" for the HP-28C.
Manuals At least four editions of the Reference Manual exist: Version 1 dated
October 1987 to version 4 dated November 1988.
This Quick Reference is based on my experience with a HP-28S version
"2BB". It is best described by edition 4 of the Reference Manual.
Author A. Thimet, V1.0, © 2003, all right reserved.