NEC PC-8201A Laptop and Tandy Model 100
The PC-8201A is an 8 bit laptop computer with an 8 line 40 character LCD display. It has built in Microsoft BASIC and Non-Volatile RAM. It is very similar to the Tandy Model 100 Laptop.

Realtime Moontracking for EME

This program written in BASIC, gives a real time display of the moon's position in Azimuth, Elevation as well as Declination. The doppler shift of 144MHz echoes is also shown in Hz. If the moon is below the horizon then the display is shown in inverse video. The Phase of the moon and the number of days since Perigee are also displayed.
 
Adapted from a moon tracking program by:- Lance Collister (W7GJ) modified by Jay Liebmann (K5JL). Published originally in Eimac EME Notes. Bulletin AS-49-13.Additional 'Moon Age' and 'Days Since Perigee' and 'Doppler Shift' were added from articles in 'Ham Radio Today'July 84 by Charles Suckling (G3WDG).
Program is Freeware, feel free to alter it, provided you rename it and reference it to my release.
Download a listing of moontrk.do for the NEC PC-8201A
 
Tandy Model 100 Computer owners - there is a version of my program which was produced by Clifford Buttschardt K7RR
(Cliff died in 2006 - a sad loss to the amateur radio community).
Download a listing of emetandy.do for the Tandy TRS80/100

Notes

The computer's time and date must be set to UTC (GMT).
Your station location (Lat/Lon) must be edited in line 588
588 L6=3:U6=29:L5=56:U5=4:REM L6 IS LON DEGREES WEST, U6 IS LON MINUTES WEST,
L5 IS LATITUDE DEGREES NORTH,U5 IS LATITUDE MINUTES NORTH
 
The default location is GM4JJJ's at 3 degrees, 29 minutes West. 56 degrees, 4 minutes North.
If you want to, you may change to your Callsign in line 587
587 W$="GM4JJJ"
Known Bugs: Year >1999, this is now partially fixed. Because the NEC clock does not supply the Century information, the software assumes that it is the 20th Century. LINE 760 has been ammended to assume that years < 90 are in the 21st century other wise they are 20th Century.
Note that since this software calculates the day of the week itself all should be OK. However because the computer also calculates the day of the week and assumes that it is in the 20th century, it will think that 2000 is 1900 and therefore not a leap year and will skip a day at February 29th 2000. You will have to reset the computer clock to the correct date.
David Anderson GM4JJJ