OSBGET
OSBGET: Read (get) a byte
Contents
Specification
6502 | Z80 | 6809 | PDP11 | 80x86 | 32016 | ARM | 68000 | RISC-V | On entry: | On exit: |
A | A | A | R0 | AL | R1 | R0 | D0 | A0 | - | = byte read |
Y | H | Y | R1 | BX | R2 | R1 | D1 | A1 | = handle | preserved |
Cy=EOF status |
If the byte read is after the end of file, the carry flag is set on exit and the EOF-error-flag is set. After the EOF byte has been read, the next read produces an error. An error is generated if the object is a directory or doesn't have read access.
Calling from BBC BASIC
-
b%=BGET#ch
calls OSBGET.
Special handles
Some systems allow BGET#0
to read from the character input stream via OSRDCH.
Entry points
- BBC BASIC Entry Address: &FFD7
- 6502 Entry Address: &FFD7, vectors via &0216
- Z80 Entry Address: &FFD7, vectors via &FFD8
- 6809 Entry Address: &FFD7, vectors via &FFD8
- 80x86 Entry Address: INT &43, vectors via 0000:010C
- 32000 Entry Address: SVC &0D
- PDP-11 Entry Address: EMT 9, vector &09
- ARM Entry Address: SWI &0A "OS_BGet", vector &0A
- 68000 Entry Address: MOV #&0A,A0:TRAP 12
- RISC-V Entry Address: ECALL &AC0009
Implementations
All filing systems implement OSBGET.
Filing System Calls | |
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Jgharston 16:56, 6 November 2009 (UTC)