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Section A:
System interface
************************************************************************
*
*
*
20 -
Read Sequential
*
*
*
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On entry:
c
14H
DE
Address of FCB
Error code
On return:
A
H
Number of blocks transferred, resp. physical error code.
Possible logical errors:
1
Read past logical end of file
9
Invalid FCB
Possible physical errors:
l
Read/write error
4
Drive not selectable
9
Question marks in file name
Differences to CP/M plus:
The multisector count has been extended to 256, instead of 128,
Differences to CP/M 2.2 resp. DiCOS:
Up to 256 blocks, corresponding to 32 KBytes of data, may be transferred
by one read operation.
According to the current multisector count, l to
256
blocks of
128
bytes
each
are read sequentially from disk and deposited in the memory buffer
specified
by
function
26.
Reading begins in the current extent
at
a
position
specified
by the Current record byte (byte 33
in
the
FCB),
Hence,
a
user program which performs sequential disk input should
set
the
Current record byte to
0
after opening the file.
When the value of
the
Current record byte exceeds 127,
the next extent is
opened
auto-
matically.
After
a successful read,
A and H are set to 0.
If reading had
to
be
aborted due to an end-of-file condition or a gap in a Random file,
A is
set to land H holds the number of blocks transferred so far,
which can
be
0
to 255.
EOS System manual
Daeumling & Zimmermann
Page 53
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