Retro Review: TI Investment Analyst

 Retro Review:   TI Investment Analyst

Today's review will be on a specialized calculator that had a very short life in the market:  the Texas Instruments Investment Analyst.  

Quick Facts:

Model:  Investment Analyst

Company:  Texas Instruments

Years:  1979-1980

Type:  Specialized Finance

Batteries: 2 x LR44

Operating Mode:  Chain

Features: Stocks, Bonds, Options

*  The [CIF] key:  which calculates (1 + i%)^n.  Used in time value of money calculations.

* Days between Dates allowing for four digit years.  The manual states that this function is accurate for the range March 1, 1900 to February 28, 2100.  The date format is mmdd.yyyy.  Example:  March 28, 2022 is 328.2022.

* The [ 2nd ] (Sec Typ) sets the security type mode.  

Stocks (Security Type A)  

We can solve for the purchase price (buy), selling price (sell), and yield.   Variables include:

**  the number of days until the first dividend is paid (B→P), the number of days from 

**  the last dividend until the stock is sold (P←S)

**  capital gains tax rate and income tax rate 

**  commissions rate when the stock is bought and sold

**  dividends, and dividend growth rate

**  The Investment Analyst has two modes for stocks:  annual yield and ownership period yield.  The latter mode is simpler.  

Bonds (Security Type B)

The keys to operate calculations for bonds are the mostly the same set of keys used for stocks.  We still solve for price (buy), selling price (sell), and yield. 

**  Annual yield mode is automatic

**  payments during investments are now coupons, which the coupon rate is entered with the [ CPN ] key

**  commissions, capital gains tax rate, and income tax rate are still included

I do believe that bonds make it into later calculators, such as the TI BA II Plus.   

Options (Security Type is "Blank")

Generally the same concept, solve for price (buy), selling price (sell), and yield; with variables including commissions, capital gains tax, and income tax.   What is different is the use of call and put prices.  

I realize that this is a short introduction, as I plan to learn more about the features of the Investment Analyst.  

Keyboard

The keys are little hard, careful pressing of them are required. I find this to be the case of TI's calculators from the late 1970s/early 1980s. Thankfully the keyboard is still workable.  

I wonder if the keyboards were lot better, calculators outside of the "mainstream" such as the Investment Analyst and the TI-54 (which I reviewed in 2018) would have been given another edition.  

Closing Thoughts

This is a curious calculator that fit a specialized niche: stocks, bonds, and options.   Not too many calculators go into this area, I believe Calculated Industries had one dedicated to Wall Street calculations.  I have a feeling I am going to learn a lot about investments from going through the well detailed manual.  

This is definitely a collector's item.  

Source:

"Texas Instruments Investment Analyst"  Datamath Calculator Museum.  December 5, 2001.  Last retrieved March 4, 2022.    http://www.datamath.org/Sci/Slimline/Investment-Analyst.htm   

Until next time,

Eddie

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Retro Review: Texas Instruments Personal Banker

Retro Review:   Texas Instruments Personal Banker

Quick Facts:

Models:  Personal Banker

Company:  Texas Instruments

Years:  1987 - 1988

Memory Register:  1 independent memory, 5 financial registers

Battery:  Solar

Finance in a Clamshell Calculator

The Texas Instruments Personal Banker is a basic solar financial calculator.   The calculator opens up like a book.  The gray case gives the calculator a professional look.

On the left side, we have the arithmetic functions with the memory functions (M+, M-, MRC).   There are three keys of note:

[ AC ]:  The key clears everything, resets the format to 2 decimal fixed mode, clear the memory register, and the financial register.  

[ CE/C ]:  Clear the last entry but keeps everything in the memory register and financial registers intact.

[ DEC ]:  This sets the fixed decimal format.  The default is 2 places.  [ DEC ] [ . ] (decimal point) sets the Personal Banker to floating mode.  

On the right side are the Time Value of Money keys:

[ 1st Amt ]:   Present Value  (PV)

[ # Pmts ]:  Number of Payments (n)

[ Int Rate ]:  Interest Rate per Period (i%)

[ Pmt Amt ]:  Payment (PMT)

[ Final ]:  Future Value (FV)

The [ Solve ] and [ Recall ] keys work exactly the way you expect.  

The cash flow convention (positive for inflows, negative for outflows) is followed.

It is very simple.  A four function calculator with a full time value of money solver.

To help the user, included with the Personal Banker are four cards:

Blue Car Symbol:  Loans & Mortgages

Red Dollar Symbol:  Savings with Periodic Deposits

Gold Stock Graph Symbol:  Investments

Green House Symbol:  Loans & Mortgage with a Balloon Payment

Keyboard

The feel of the keys are solid.  However, the keys take a small fraction of a second for the key to register, so make sure the key registers before typing the next key.  

Verdict

The Personal Banker is a basic financial calculator.  I really like the folding design on this calculator and how the keys work.  Unfortunately, the high price point of $50 (see source) and it's basic set of functions (arithmetic, percent, time value of money, but no cost-sell-margin solver, amortization, statistics, logarithms, or exponents) did not help sales of the Personal Banker.  

It is a good collector item, since vintage solar-powered Texas Instruments financial calculators yield premium prices.

Source

Woerner, Joerg.  "Texas Instruments TI-2600 Personal Banker"  Datamath.  Updated July 22, 2002.  Retrieved January 23, 2021.  http://www.datamath.org/Sci/Modern/PersonalBanker.htm

On Sunday, we'll take another trip back in time.  

Eddie

All original content copyright, © 2011-2021.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

HP Prime: Combined Internal Rate of Return

HP Prime: Combined Internal Rate of Return

Introduction

An investor has several projects, each with their own initial investments and discount rate.  The net present value is calculated (NPV) for each project.  If the investor combined all the projects into one set of cash flows, what is the effective internal rate of return (IRR)?  The program COMBIRR tackles this question.

For example, an investor has the following projects, each lasting five years:

Project A:  NPV:  -$3,500, discount rate: 10%

Project B:  NPV:  $18,000, discount rate: 12%

Project C:  NPV:  $20,000, discount rate: 9%

If the investor combines all three projects, what would be the combined internal rate of return?  I use the following steps:

1. Calculate the NUS (net utility stream) of each project.  Since we are only given the net present value in this case, will need to determine a payment flow.  The NUS calculates the cash flow of each year, assuming they are equal.  Setup:  N = number of years, I/YR = discount rate, PV = -NPV, FV = 0, P/Y = 1.

2.  Combine the present values from each project, along with net utility streams calculated from each project.  Calculate IRR.  Setup:  CF0 = -ΣNPV, Cash Flows = ΣNUS, frequency length of project

This procedure, like the program COMBIRR, assumes that each project has the same length.  With some adjustments, you can calculate combined IRR using projects of the same length.

Going back to our example:

 
Project A:  NPV:  -$3,500, discount rate: 10%, NUS: -$569.61

Project B:  NPV:  $18,000, discount rate: 12%, NUS: $3,185.71

Project C:  NPV:  $20,000, discount rate: 9%, NUS: $3,116.40

ΣNPV:  $34,500, ΣNUS:  $5,732.50

Calculate IRR with CF0 = -34500.00, Cash Flows:  5,732.50 with a frequency of 5

Result:  10.49  (Combined IRR: 10.49%)

How to Run COMBIRR:

1. Enter the length of each of the projects.  COMBIRR assumes each project has the same length.

2.  Enter the NPV and discount RATE for the first project.  Each time the program will ask you “ENTRY?”.  Select YES for additional entries, NO to stop entering amounts.

3.  The combined IRR is calculated. 

HP Prime Program: COMBIRR

sub1(); // data subroutine

EXPORT COMBIRR()

BEGIN

// EWS 2018-05-10

// Combined IRR using

// same length projects

// initialize

LOCAL L1,U,T,L,C;

LOCAL h,N,I;

// input

INPUT(L,"Number of Periods",

"LEN: ");

// entry routine

REPEAT

L1:=sub1(); N:=L1(1); I:=L1(2);

T:=T-N;

U:=U+Finance.TvmPMT(L,I,−N,0,1);

CHOOSE(h,"ENTRY?","YES","NO");

UNTIL h==2;

// calculate combined IRR

C:=Finance.CashFlowIRR(

{T,{U,L}},1);

RETURN C;

END;

// data entry subroutine

sub1()

BEGIN

LOCAL x1,x2;

INPUT({x1,x2},"Data Entry",

{"NPV: ","RATE: "});

RETURN {x1,x2};

END;

Eddie

All original content copyright, © 2011-2018.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.  Please contact the author if you have questions.