INKEY

INKEY and INKEY$ are BASIC functions to:

• wait a specified time for a character from the input stream
• test for a keypress
• return a value indicating the machine host/operating system type

INKEY

Availability	Present in all versions of BBC BASIC.
Syntax	<numeric> = INKEY<numeric>	<string> = INKEY$<numeric>
Token (hex)	A6 (function)	BF (function)
Description	Reads an character from the input stream.

Description

INKEY and INKEY$ call OSBYTE &81. INKEY returns a character or -1 for no character, INKEY$ returns a one-character string or a null string if nothing returned.

Wait for input character

   Argument: >=0
   Returns:  >=0, character returned
             -1, timed out
   
   Example:  key%=INKEY(200)
             REPEAT:k%=INKEY(10):PROCtick:UNTIL k%>-1
   
   Some systems allow a delay value with b15 set to return a 16-bit "deep"
   keyvalue distinguishing between special keys, such as function keys, and
   top-bit characters.
   
   Example:  REPEAT:key%=INKEY(&80C8):UNTIL key%>-1
             IF key%=&190 THEN PRINT "Shift-f0 pressed"

Scan for a particular key

   Argument: -1..-128, negative key number
   Returns:  TRUE, key pressed
             FALSE, key not pressed

Scan for a range of keys

   Argument: -129...-255, lowest internal key number to start at EOR&7F
   Returns:  internal key number pressed, or 255 for none

Check machine type

   Argument: -256
   Returns:  A value indicating the host (I/O) machine type:
            &00 BBC B with MOS 0.10
            &00 RM Nimus
            &01 Acorn Electron MOS
            &FF BBC Micro OS 1.00/1.20
            &FE BBC Micro (American MOS 1.10)
            &FE NetBSD
            &FD Master 128 MOS 3.20
            &FC BBC Micro (West German MOS)
            &FC Windows 32
            &FB BBC B+ 64/128 (MOS2.00)
            &FB Beos (Brandy Basic)
            &FA Acorn ABC
            &FA DOS with Brandy BASIC
            &F9 Linux
            &F8 MacOS X (Brandy Basic)
            &F7 Master ET OS 4.00
            &F7 FreeBSD
            &F6 OpenBSD
            &F5 Compact
            &F5 Amiga (Brandy Basic)
            &F4 Master 128 MOS 3.26
            &Ex Spectrum
            &Dx Amstrad 464/664/6128, etc.
            &Cx Commodore 64/64+/128, etc.
            &Ax Arthur/RISC OS
            &A0 Arthur 1.20
            &A1 RISC OS 2.00
            &A2 RISC OS 2.01
            &A3 RISC OS 3.0x
            &A4 RISC OS 3.1x
            &A5 RISC OS 3.50
            &A6 RISC OS 3.60
            &A7 RISC OS 3.7x
            &A8 RISC OS 4.0x
            &A9 RISC OS 4.3x
            &AA RISC OS 5.xx
            &AF Springboard
                (INKEY-256 AND &F0)=&A0 gives TRUE for ARM hardware
            &68 6809 system
            &63 6309 system
            &57 BBC BASIC for Windows (ie ASC"W")
            &53 BBC BASIC for Intel CPU on SDL abstraction (ie ASC"S")
            &73 BBC BASIC for ARM CPU on SDL abstraction (ie ASC"s")

Depending on what the program needs to know, OSBYTE &00 is usually the more appropriate call to make.

See Also

• http://mdfs.net/Docs/Comp/BBC/Osbyte80
• http://mdfs.net/Docs/Comp/Acorn/HostVals
• http://mdfs.net/Docs/Comp/Acorn/Hosts
• What BASIC is running
• Negative INKEY numbers

References

Jgharston 12:27, 28 May 2009 (UTC)