Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!usc!apple!bionet!synoptics!unix!hplabs!hp-pcd!hpcvra!rnews!hpcvbbs!akcs.dnickel From: akcs.dnickel@hpcvbbs.UUCP (Derek Scott Nickel) Newsgroups: comp.sys.handhelds Subject: Re: RPL constructs Message-ID: <27222fde-393.4comp.sys.handhelds-1@hpcvbbs.UUCP> Date: 21 Oct 90 23:40:05 GMT References: <11408@life.ai.mit.edu> <11423@life.ai.mit.edu> Lines: 53 BCD numbers (binary coded decimal) are represented by a mantissa, sign and exponent fields. There are two kinds of BCD numbers in the HP 48SX, 12-form and 15-form BCD numbers, called BCD12 and BCD15 in the field descriptions. Both kinds have several things in common: * A mantissa. Each digit of the number is represented by one nibble in the mantissa. 12-form BCD numbers have a 12 digit mantissa and 15-form BCD numbers have a 15 digit mantissa. There is an implied decimal point after the Most Significant Digit (msd) with respect to the exponent. * A sign nibble. Positive numbers are represented by a 0 and negative numbers are represented by a 9. * An exponent. The exponent is in 10's compement. 12-form BCD numbers have a 3 nibble exponent and 15-form BCD numbers have a 5 digit exponent. 12-form BCD numbers are the basis for Real Number, Complex Number, Real Array and Complex Array data types. 15-form BCD numbers are the basis for Long Real and Long Complex data types. BCD12: 15 14 3 2 0 +--+------------------------+------+ |S | msd.. Mantissa ..lsd | Exp | +--+------------------------+------+ 1 12 5 BIN15: 21 20 5 4 0 +--+------------------------------+----------+ |S | msd... Mantissa ...lsd | Exp | +--+------------------------------+----------+ 1 15 5 ------------ This is from my 'HP 48SX Internals' document that is getting close to its first posting. Hope it helps. Take a look at the Real Number and Long Real objects starting with 0 (Real Number) at 2A2B4 to 10 (Long Real) at 2A596. There are 34 objects in that range. Most are simple. But includes PI and MAXR... Good Luck! Derek S. Nickel