The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Powering Up
Listing 3-3.
Allows user to read and write to external memory.
10 DO
20 INPUT “Enter 0 (read), 1 (write), or 2 (quit): ”,RW
30 IF RW=0 THEN GOSUB 70
40 IF RW=1 THEN GOSUB 120
50 WHILE RW2
60 END
70 PH0."External RAM ranges from 0 to “,MTOP
80 INPUT “Enter an address to read : ”,A
90 B=XBY(A)
100 PH0.B," is stored in address “,A
110 RETURN
120 PH0."Free memory ranges from “,LEN+512,” to “,MTOP
130 INPUT “Enter an address to write to :”,A
140 INPUT “Enter data to be written :”,B
150 XBY(A)=B
160 PH0.B," has been written to address “,A
170 RETURN
For the timer to be accurate, you must set XTAL to match the timing crystal your system
uses.
Further Experiments
Feel free to continue experimenting with BASIC-52 programs, using the programming
reference as a guide. You can do quite a bit with just these circuits.
Listing 3-4. Real-time clock.
10 CLOCK 1:TIME=0:SEC=0
20 DO
30 ONTIME 1,60
40 WHILE SEC