This is a simple and short test program I wrote while testing out emulators.
PROG : 16509
D-FILE: 16703
VARS : 17496
E-LINE: 17497
STKBOT: 17497
STKEND: 17497
9999 means line number
PRINT means treat as KEYWORD P
10 REM **TEST**SLR/2020**
20 LET X=5+INT (RND*10)
30 PRINT AT 21,X;"ZX81"
40 LET R=INT (RND*3+1)
50 LET X=X-(R=1 AND X>0)+(R=2
AND X<28)
60 SCROLL
70 GOTO 30
100 SAVE "TEST"
110 RUN