OSBGET

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Read (get) a byte

Contents 1 Specification 2 Calling from BBC BASIC 3 Special handles 4 Entry points 5 Implementations

Specification

On entry:
Y	= handle

On exit:
A	= Byte read
X	preserved
Y	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:
• 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

Implementations

All filing systems implement OSBGET.

Jgharston 10:57, 2 September 2008 (BST)