Time Value of Money

Description

This program computes the time value of money similar to the HP-12C financial calculator.

The user definable function keys A-E behave much like the (n,i,PV,PMT,FV) keys on the HP-12C financial calculator. You enter any three of these values (pressing it's function key) and compute the 4th or 5th value by pressing CLx followed by the function key of the missing value, and the R/S key. The difference is on the HP12C you don't need to press the R/S key, but otherwise this program behaves exactly like the HP-12C. If you set Flag(0), calculations are based on payments at the Beginning of the payment period, (Like "g Beg" on the HP-12C). If you clear Flag(0), calculations are based on payments at the End of the payment period (Like "g End" on the HP-12C).

Examples:

9 CF 0 (Payments at the end of payment periods)
30 ENTER 12 × A (Set number of payment periods to 360 months, "30 years")
5.85 ENTER 12 / B (Set the interest rate at 5.85% per year or .4875% per month)
5000 C (Loan amount $50,000; positive is borrowed money)
D R/S (Compute the monthly payment shows -294.97 per month; negative is payment)
CLx D (Clears out the payment register so Future Value can be computed)
E R/S (Computes future value of loan shows -287,941.99; negative is payed out money)

Program Resources

Labels

Name	Description	Name	Description
A	Number of compounding periods (n)	0	# Internal subroutine label. Used as error indicator.
B	Interest per compounding period (i)	1	# Internal subroutine label
C	Present Value of annuity (PV)	2	# Internal subroutine label
D	Payment (PMT)	3	# Internal subroutine label
E	Future Value (FV)	4	# Internal subroutine label

Storage Registers

Name	Description	Name	Description
0	Used during calculations	5	Saves (FV)
1	Saves (n)	6	Used during calculations
2	Saves (i)	7	Used during calculations
3	Saves (PV)	8	Used during calculations
4	Saves (PMT)

Flags

Number	Description
0	Set = "g Beg", Cleared = "g End"
1	Used during calculations

Program

Line	Display	Key Sequence	Line	Display	Key Sequence	Line	Display	Key Sequence
000			037	42,21, 4	f LBL 4	074	43, 4, 1	g SF 1
001	42,21,11	f LBL A	038	26	EEX	075	1	1
002	44 1	STO 1	039	2	2	076	45 2	RCL 2
003	31	R/S	040	20	×	077	43 14	g %
004	32 1	GSB 1	041	44 2	STO 2	078	42,21, 3	f LBL 3
005	43 36	g LSTΧ	042	43 32	g RTN	079	44 8	STO 8
006	45,20, 0	RCL × 0	043	42,21,13	f LBL C	080	1	1
007	45 5	RCL 5	044	44 3	STO 3	081	44 0	STO 0
008	34	x↔y	045	31	R/S	082	40	+
009	30	−	046	32 1	GSB 1	083	43,30, 4	g TEST x≤0
010	43 36	g LSTΧ	047	32 2	GSB 2	084	22 0	GTO 0
011	45,40, 3	RCL + 3	048	16	CHS	085	44 6	STO 6
012	43 20	g x=0	049	44 3	STO 3	086	43, 6, 0	g F? 0
013	22 0	GTO 0	050	43 32	g RTN	087	44 0	STO 0
014	10	÷	051	42,21,14	f LBL D	088	45 1	RCL 1
015	16	CHS	052	44 4	STO 4	089	16	CHS
016	43,30, 4	g TEST x≤0	053	31	R/S	090	14	yˣ
017	22 0	GTO 0	054	1	1	091	44 7	STO 7
018	43 12	g LN	055	44 4	STO 4	092	1	1
019	45 6	RCL 6	056	32 1	GSB 1	093	34	x↔y
020	43 12	g LN	057	45 3	RCL 3	094	30	−
021	10	÷	058	32 2	GSB 2	095	43 20	g x=0
022	44 1	STO 1	059	34	x↔y	096	22 0	GTO 0
023	43 32	g RTN	060	10	÷	097	45,20, 0	RCL × 0
024	42,21,12	f LBL B	061	16	CHS	098	45 4	RCL 4
025	44 2	STO 2	062	44 4	STO 4	099	45,10, 8	RCL ÷ 8
026	31	R/S	063	43 32	g RTN	100	20	×
027	48	.	064	42,21,15	f LBL E	101	43, 6, 1	g F? 1
028	2	2	065	44 5	STO 5	102	43 32	g RTN
029	36	ENTER	066	31	R/S	103	45,40, 3	RCL + 3
030	26	EEX	067	32 1	GSB 1	104	42,21, 2	f LBL 2
031	16	CHS	068	45,40, 3	RCL + 3	105	45 5	RCL 5
032	3	3	069	45,10, 7	RCL ÷ 7	106	45,20, 7	RCL × 7
033	43, 5, 1	g CF 1	070	16	CHS	107	40	+
034	42,10, 3	f SOLVE 3	071	44 5	STO 5	108	43 32	g RTN
035	22 4	GTO 4	072	43 32	g RTN
036	22 0	GTO 0	073	42,21, 1	f LBL 1