^ma 1 18 ^pl 0 ^ju ^me EXPAND ^ceTHE AECROM ^ce===**====== ^me NORMAL ^ma 1 38 ^ju This is a ROM which is intended for Architects, Engineeers and others working in the Construction industry. It will also be of great use to those who frequently work with several different units of length and need to make many conversions between them. ^sk1The AECROM can be divided into 6 sections and this review will deal with each in turn. ^sk1[1] UNIT OF LENGTH MODE ^sk0----------------------- ^sk0Four of the functions in the AECROM activate the four unit of length modes:- ^pa^co>DF - Decimal Feet ^pa^co>DI - Decimal Inches ^pa^co>F - Fractions ^pa^co>M - Decimal Metres ^juAll four are programmable. >DF is the normal operating mode of the HP41. Digits to the left of the decimal point represent integer feet and the digits to the right represent the DECIMAL part of a foot . Entering the Decimal Inch mode, by XEQ Alpha >DI Alpha, will convert all numbers in the stack into inches. Clearing the X register will show 00.00 rather than 0.00 (the 'normal' result). Entering the Decimal Metre mode, by XEQ Alpha >M Alpha, will convert the stack contents to metres. Care must be taken when multiplying or dividing Decimal Inch or Decimal Metre quantities by INTEGER values as you will not get the correct answer. This is because of the way that the Units mode stores numbers. You use the '/CONV' function to 'correct' a multiplication and the '*CONV' function to 'correct' a division. 4 metres * 4 will show 52.49 and '/CONV' will correct this to show 16.00; similarly 16 metres / 4 will show 1.22 but subsequent use of the '*CONV' command will correct this to 4.00 - as you would expect ! Remember to carry out a '/CONV'or '*CONV' for EACH multiplication or division : the example on page 27 of the manual is faulty in this respect as the 2nd '/CONV' necessary to provide the correct answer is missing. FRACTIONS mode, activated by XEQ Alpha >F Alpha, is the most interesting of the four units of length modes. It is the only mode which needs anything special in the way of input. Numbers are input in an x.yyz format where x is an integer number of feet, yy is a TWO figure number of INTEGER inches and f is the fraction of an inch. If f is 2 digits, then the fist digit will be the numerator and the second digit will be the denominator. If f is either 3 or 4 digits then the LAST two should be 16 - 516 would be 5/16 ths of an inch and 1516 would be 15/16 ths of an inch. All subsequent quantity calculations will display the result in fractional mode. 5.00316 (5'00-3/16") ENTER 7.0778 (7'7-7/8") + will show the correct result of 12'8-1/16". If a number in fractional mode causes the display to overflow a colon apears on the RHS of the display indicating that the leading digit(s) are not visible. 234567'7-7/8" will show as 34567'7-7/8": showing that at least one leading digit is not shown. If you work through the examples in this section you will understand the Units of Length mode and be able to use it with ease. ^sk1The manual warns the user that an AECROM should not be put in an HP41 at the same time as as a ZENROM or CCD ROM. One of the features of the AECROM is that once an HP41 has been placed in a particular unit of length mode the HP41 remembers that mode - even if the AECROM is removed. Put the AECROM back and the HP41 will be in the same unit of length mode as it was before you took it out - provided you have not used either a ZENROM or CCD ROM in the meantime. If a ZENROM and an AECROM are in the HP41 together then the AECROM unit of length mode will not work and the operation of AECROM programs are likely to be disrupted. AECROM functions, however, seem to work normally. ^sk1[2] THE PROGRAM GENERATOR ^sk0------------------------- ^sk0The Program Generator allows the user to enter an algebraic formula (subject to certain restrictions) into the HP41, prompts the user to give 'labels' to each of the variables used in the formula and then creates a program to evaluate the formula. The restrictions as to what may be entered are:- ^co 1. Left Bracket 12. + 2. Square root 13. - 3. LOG 14. * 4. LN 15. / 5. MOD 16. SIGN 6. Trig functions 17. FACT (!) 7. Hyperbolic 18. A to Z, e & PI functions 8. FRC 19. The decimal point 9. INT 20. The digits 0 to 9 10. EEX 21. - Low priority 11. ^ multiply ^ju^sk1The last named function - LOW PRIORITY MULTIPLY - does the same as '*' but works after '+' and '-'. ^sk1As part of the 'programming' process it will prompt you for the minimum SIZE required. If there is insufficient space in the HP41C then you will be prompted to 'TRY AGAIN'. Having 'written' your program the AECROM leaves the HP41 poised at the beginning of the program - key R/S and program execution begins. Please note that as the AECROM is programming formulas it writes 'top-to-bottom' programs,ie:- NO GOSUBS or GTO's. ^sk1[3] THE CURVE FITTER ^sk0-------------------- ^sk0The AECROM uses a program, "CURVE", and a function, CRVF, to fit data pairs to one of the following 16 curves:- ^co^sk1 1. LINEAR : y=a+bx 2. RECIPROCAL : y=1/(a+bx) 3. HYPERBOLA : y=a+b/x 4. RECIPROCAL OF HYPERBOLA : y=x/(ax+b) 5. POWER : y=ax^b 6. MODIFIED POWER : y=ab^x 7. ROOT : y=ab^1/x 8. EXPONENTIAL : y=ae^(bx) 9. LOGARITHMIC : y=a+b(LNx) 10. LINEAR HYPERBOLIC : y=a+bx+c/x 11. 2nd ORDER HYPERBOLIC : y=a+b/x+c/x^2 12. PARABOLA : y=a+bx+cx^2 13. LINEAR EXPONENTIAL : y=ax/(b^x) 14. NORMAL : y=ae^(((x-b)^2)/c) 15. LOG NORMAL : y=ae^(((b-LNx)^2)/c) 16. CAUCHY : y=1/(a+(x+b)^2+c) ^ju^sk1"CURVE" automatically chooses the best fit curve though the user may specify the curve (from the list above) which is to be used in the curve fitting process. Once the data has been fitted to a curve then Y values can be calculated for given values of X. "CURVE" is menu driven. "CURVE" uses the local label keys 'A'-'E' and 'a' so you should clear these keys of any assigned functions or programs. ^sk1Aside from the number of possible curves, the above is quite normal for any Curve Fitter. What is impressive is the speed - CRVF sees to that. You can, of course, use CRVF in your own curve fitting programs. A good book in that field is "CURVE FITTING FOR PROGRAMMABLE CALCULATORS" by William M. Kolb. ^sk1[4] GEOMETRIC SOLVERS ^sk0--------------------- ^sk0The AECROM provides three geometric solvers in the form of FOCAL programs. They are "SARR" (Slope, Angle, Rise and Run), "TRIA" (Triangle Solver) and "CIRC" (Circle Solver). ^sk1"SARR" - Provides an interchangeable solution for the three sides and slope angle of a right angled triangle. ^sk0"TRIA" - Provides an interchangeable solution for the triangle given three of the three sides and three angles. ^sk0"CIRC" - Given the radius, the sector angle (angle at the centre of the circle) and XDIS (distance along a chord measured away from the centre of the chord) the user can employ "CIRC" to find the diameter, area of the circle, circumference, arc length, chord length, chord rise, sector area and segment area. ^sk1I believe the first two solvers are totally unworthy of inclusion in this ROM. They are a simple application of basic trignometry and unless you have hundreds of such calculations to do, the time saving is irrelevant. The third solver is better, for the calculations are a little more difficult, and would be worthy of inclusion if as part of a spherical geometry capability - as it is I feel the romspace used is wasted. ^sk1[5] HYPERBOLIC FUNCTIONS ^sk0------------------------ ^sk0The hyperbolic functions included are SINH, COSH, TANH, ASINH, ACOSH and ATANH. Hyperbolic calculations, using standard formulae, are not quick, even if done with the aid of a calculator. Provision, therfore, of hyperbolics as functions rather than as FOCAL subroutines will be welcomed by many and their inclusion is definetly deserved. ^sk1[6] UTILITY FUNCTIONS ^sk0--------------------- ^sk0 9 Utility functions are provided by the AECROM :- ^sk1ACD - Accumulates the DISPLAY (not the Alpha register) to the printer buffer. ^sk0PRAD - Prints the information in DISPLAY left justified and the information in ALPHA right justified (similar to FMT which, if I am correct, works with Alpha and X registers). ^sk0PRD - Prints the DISPLAY in a running program. ^sk0VIEWX - Converts the information in the X register into the current unit of length mode. If you want the printed information to reflect the current unit of length mode you should use VIEWX before ACD, PRAD and PRD. ^sk0WAIT - Temporarily halts the program to show the user the display - use it rather than PSE to display information tha was produced using VIEWX. ^sk0CLBUF - Clears the printer buffer ONLY if there is something in it. ^sk0PLC - Prints a line 24 characters long (in CF 12 mode) or 12 characters long (in SF 12 mode) of the first character in Alpha. ^sk0DMS - produces a proper DMS display for an HR angle in the X register. To a field surveyor this is heaven. In my experience the occaisional confusion between D.MMSS and D.DDDD (in FIX4) on site can cause damage out of all proportion. DMS should prevent that and is much quicker than the best FOCAL solutions to the problem. ^sk0LPS - displays the seconds of a DMS angle to the calculator's present FIX mode. ^sk1The first 7 functions make it possible to 'use' the display as a seperate output 'register' and to print the display. The last two functions are unique to the AECROM and provide a solution to one of the most common calculations done by site engineers. ^sk1CONCLUSION ^sk0---------- ^sk0This is a worthwhile module for those who regularly use Metric and Imperial units of length and who need to switch between the two often. The 'Program Generator' is of particular value in those conditions where you need to evaluate a formula and do not have the time to derive an RPN version with suitable prompts. It is unique to the AECROM (save for the recently announced HP28C) and for many will alone justify the cost of the ROM. Provision of hyperbolics as funtions rather than short programs will please those who need them frequently. The Curve Fitter is quicker and more comprehensive than anything else in an HP41 ROM that I have seen. The three Geometric Solvers are, I believe, of dubious value. Most HP41 users should be able to write their own solutions to these problems. The AECROM Utility functions ARE usefull - they allow the user to 'use' the difference between the DISPLAY and the ALPHA register. Surveyors and civil engineers will enjoy the DMS function as well as LPS. Both functions are unique to this ROM. Their speed advantage over FOCAL solutions removes the irritation that the latter possess. I wish I had had this facility when working as a site engineer. ^sk1The AECROM is manufactured by REDSHIFT SOFTWARE and is available from EduCalc for $89.95 + p&p. If you want to try it, then give me a buzz and I will bring it to the next London meeting.