Sinclair QL User Manual

Programming
30
proc getnum; m$,min,max
rem ***** get number in range *****
local wrong
let _rong=1
whi le wrong
print m$; "? II;
error readnum
let wrong=errnumO
if not wrong
if num<min or num>max
let wrong=1
print "Allowed range ;s ";min;" to ";max
endif
endif
if wrong
print "Try again"
end if
endwhi le
endproc
Since error must be followed by the name of a procedure. we define readnum to input
a value
for the vanable num.
proc readnum
input num
endprac
Suppose you want a procedure thaf checks that a number is within the range 1 to 10
You can do this uSing getnum in the following way:
prac check
getnum; "Numeric value?",1,10
endproc
12/S-l

Sinclair QL Specifications

General

Processor	Motorola 68008
Clock Speed	7.5 MHz
RAM	128 KB (expandable to 640 KB)
ROM	48 KB
Operating System	Sinclair QDOS
Release Year	1984
Storage	Microdrive tape loop
Graphics	256x256 pixels, 8 colors
Ports	RS-232, ROM cartridge
Sound	Beeper (internal speaker)