OSBGET

OSBGET: Read (get) a byte

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
OSFILE : File and directory operations OSARGS : Information on open objects OSBGET : Read (get) a byte OSBPUT : Write (put) a byte	OSGBPB : Read or write multiple bytes of data OSFIND : Open or close an object FSCV : Filing system control

Jgharston 16:56, 6 November 2009 (UTC)