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68 lines
2.9 KiB
Plaintext
68 lines
2.9 KiB
Plaintext
The '''PEEK''' function returns the value that is contained at a certain memory address offset. '''QB64 currently has limited access!'''
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{{PageSyntax}}
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:: variable = PEEK(''segment_offset'')
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* Reads the specified memory ''segment_offset'' value.
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* Use [[DEF SEG]] before PEEK to specify which memory segment to work in.
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* PEEK only reads the memory byte value. Not certain bits. (See [[AND]])
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* Important [[SCREEN (statement)|SCREEN]] segments using [[PEEK]] and [[POKE]] include &HB800 (text segment) and &HA000 (graphics segment).
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* To return to Basic default segment use [[DEF SEG]] without any arguments.
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* '''Warning: DEF SEG, VARSEG , VARPTR, PEEK or POKE access QB64's emulated 16 bit conventional memory block!'''
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: '''It is highly recommended that QB64's [[_MEM]] memory system be used to avoid running out of memory.'''
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''Example:'' Checking the 8 keyboard bit settings using a PEEK return value.
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{{CodeStart}} '' ''
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SCREEN 12
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{{Cl|DEF SEG}} = 0 ' BIOS area
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oldvalue = PEEK(1047) ' IMPORTANT! save initial setting to reset later
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DO: {{Cl|_LIMIT}} 100
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port = {{Cl|PEEK}}(1047)
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IF port > 0 THEN LOCATE 26, 19: COLOR 11:
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PRINT "Turn ALL Locks off to see each key's bit value!"
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END IF
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COLOR 14:LOCATE 2, 25
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PRINT "PEEK(1047) ="; port; "present keyboard port byte value"
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LOCATE 5, 35
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IF (port {{Cl|AND}} 1) = 1 THEN COLOR 10: PRINT "R SHIFT PRESSED " ELSE COLOR 12: PRINT "R SHIFT RELEASED"
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LOCATE 7, 35
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IF (port AND 2) = 2 THEN COLOR 10: PRINT "L SHIFT PRESSED " ELSE COLOR 12: PRINT "L SHIFT RELEASED"
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LOCATE 9, 35
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IF (port AND 4) = 4 THEN COLOR 10: PRINT "CTRL KEY PRESSED " ELSE COLOR 12: PRINT "CTRL KEY RELEASED"
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LOCATE 11, 35
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IF (port AND 8) = 8 THEN COLOR 10: PRINT "ALT KEY PRESSED " ELSE COLOR 12: PRINT "ALT KEY RELEASED"
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LOCATE 13, 35
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IF (port AND 16) = 16 THEN COLOR 10: PRINT "SCROLL LOCK ON " ELSE COLOR 12: PRINT "SCROLL LOCK OFF"
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LOCATE 15, 35
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IF (port AND 32) = 32 THEN COLOR 10: PRINT "NUMBER LOCK ON " ELSE COLOR 12: PRINT "NUMBER LOCK OFF"
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LOCATE 17, 35
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IF (port AND 64) = 64 THEN COLOR 10: PRINT "CAPS LOCK ON " ELSE COLOR 12: PRINT "CAPS LOCK OFF"
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LOCATE 19, 35
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IF (port AND 128) = 128 THEN COLOR 10: PRINT "INSERT MODE ON " ELSE COLOR 12: PRINT "INSERT MODE OFF"
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COLOR 11: LOCATE 21, 20: PRINT "Press mode keys to change or [ESC] to quit!";
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LOOP UNTIL {{Cl|INP}}(&H60) = 1 ' escape key exit
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{{Cl|POKE}} 1047, oldvalue ' IMPORTANT reset to original settings
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{{Cl|DEF SEG}} '' ''
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{{CodeEnd}}
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: '''NOTE: Keyboard Port function key settings cannot be reset on NT machines!'''
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''See Example:'' [[SelectScreen]] (Screen 0 row highlighting)
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''See also:''
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* [[POKE]] {{text|(write to memory)}}, [[INP]] {{text|(read register)}}
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* [[DEF SEG]], [[VARSEG]], [[VARPTR]]
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* [[_MEMGET (function)]], [[_MEMPUT]]
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* [[DEF SEG = 0]], [[Scancodes]] {{text|(demo)}}
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* [[PEEK and POKE Library]]
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* [[Screen Memory]]
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{{PageNavigation}}
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