OSBYTE &81 (129) - Read Key with Time Limit or Machine Type. Called by BASIC's =INKEY function.
Action: Read key with time limit On entry: X=0..255 Y=0..127 On exit: Cy=0, Y=0, X=character read Cy=1, Y=255 timed out Cy=1, Y=27 ESCAPE was pressed The caller can test for either Y=0 or Cy=0 for a valid returned character.
Action: Read machine sub-type Often OSBYTE &00 is a more appropriate call to make. On entry: X=0 Y=255 On exit: X=value identifying a sub-type of the host OS X=&00 BBC A/B with OS 0.10 X=&00 RM Nimus X=&01 Acorn Electron OS X=&FF BBC Micro OS 1.00/1.20/1.23, Reuters OS R0.3 with *UK X=&FE BBC Micro (American OS A1.0), Reuters OS R0.3 with *US X=&FE NetBSD X=&FD Master 128 MOS 3.20/3.50 X=&FC BBC Micro (West German MOS) - see note X=&FC Windows 32 X=&FB BBC B+ 64/128 (OS 2.00) X=&FB Beos (Brandy Basic) X=&FA Acorn Business Computer OS 1.00/2.00 X=&FA Cambridge Workstation OS 2.10 X=&FA DOS with DJGPP extender (Brandy Basic) X=&F9 Communicator X=&F9 Linux X=&F8 MacOS X (Brandy Basic) X=&F7 Master ET MOS 4 X=&F7 FreeBSD X=&F6 OpenBSD X=&F5 Master Compact MOS 5 X=&F5 Amiga (Brandy Basic) X=&F4 Master 128 MOS 3.26 X=&F4 GNU FreeBSD (Brandy Basic) X=&F3 GNU (Brandy Basic) X=&Ex Spectrum X=&E0 ZX Spectrum (INKEY-256 AND &F0)=&E0 gives TRUE for ZX Spectrum hardware X=&Dx Amstrad 464/664/6128, etc. (INKEY-256 AND &F0)=&D0 gives TRUE for Amstrad CPC hardware X=&Cx Commodore 64/64+/128, etc. (INKEY-256 AND &F0)=&C0 gives TRUE for Commodore hardware X=&Bx PDP11 Unix X=&B7 PDP11 Unix Version 7 X=&B6 PDP11 Unix Version 6 X=&B5 PDP11 Unix Version 5 (INKEY-256 AND &F0)=&B0 gives TRUE for PDP11 hardware X=&Ax ARM-based systems X=&A0 Arthur 1.20 X=&A1 RISC OS 2.00 X=&A2 RISC OS 2.01 X=&A3 RISC OS 3.0x X=&A4 RISC OS 3.1x X=&A5 RISC OS 3.50 X=&A6 RISC OS 3.60 X=&A7 RISC OS 3.7x X=&A8 RISC OS 4.0x X=&A9 RISC OS 4.3x X=&AA RISC OS 5.xx X=&AE RISC OS Pyromaniac X=&AF Springboard (An ARM-based development system plugged into a PC) (INKEY-256 AND &F0)=&A0 gives TRUE for ARM hardware X=&8x Texas Instruments Calculator X=&83 TI-83+(SE) X=&84 TI-84+(SE) (INKEY-256 AND &F0)=&80 gives TRUE for TI Calculator hardware X=&68 6809 system X=&63 6309 system X=&73 BBC BASIC on SDL abstraction from C source (ie ASC"s") X=&57 BBC BASIC for Windows (ie ASC"W") X=&53 BBC BASIC SDL abstraction from assembly language source (ie ASC"S") (INKEY-256 AND &DB)=&53 gives TRUE for R.T.Russell's BBC BASIC for Windows/SDL/etc X=&4D Matrix Brandy BASIC (ie ASC"M") for all builds from V1.22.6 except RISC OS.
The known examples of German BBC MOS return X=&FF.
Action: Scan for a range of keys On entry: X=1..127 lowest internal key number to start at EOR &7F Y=255 On exit: X=internal key number pressed (or 255 for none)
Action: Scan for a particular key On entry: X=128..255 internal key number to scan for EOR &80 Y=255 On exit: X=Y=0 for as not pressed X=Y=255 the key was being pressed
The parameter to OSBYTE &81 is a 16-bit number. The standard implementation interprets that as:
<&8000 - wait for keypress &FF00+nn - scan for BBC keypress &FF00 - return host machine type
A parameter of &8000-&FEFF is undefined. Some systems extend INKEY as follows:
&FE00+nn - scan for low level DOS/Window VK_xxxx keypress (cZ80Tube, console library) &FC00+nn - scan for low level SDL1.2 SDK_xxx keypress (Brandy Basic SDL builds) &8000+nn - wait for keypress, return 16-bit character code (cZ80Tube, console library)
- OSBYTE &00
- What BASIC is running
- Negative INKEY numbers
Jgharston 21:56, 26 May 2009 (UTC) Jgharston (talk) 05:20, 23 June 2018 (CEST) Jgharston (talk) 22:09, 25 August 2019 (CEST) Jgharston (talk) 20:03, 16 February 2020 (CET) Jgharston (talk) 07:08, 12 April 2020 (CEST)