1 <!doctype linuxdoc system>
4 <title>Diskette Sector I/O Routines
5 <author>Christian Groessler, <htmlurl url="mailto:cpg@aladdin.de" name="cpg@aladdin.de">
9 The cc65 library provides functions to read and write raw disk sectors.
10 Include the dio.h header file to get the necessary definitions.
13 <!-- Table of contents -->
16 <!-- Begin the document -->
18 <sect>Opening the disk for low level I/O<p>
20 Prior to using these functions a handle to the drive has to be obtained. This
21 is done with the <tt>dio_open</tt> function. After use, the handle should be
22 released with the <tt>dio_close</tt> function.
25 dhandle_t __fastcall__ dio_open (driveid_t drive_id);
28 The <tt>drive_id</tt> specifies the drive to access, with 0 being the first
29 disk drive, 1 the second, and so on.
32 unsigned char __fastcall__ dio_close (dhandle_t handle);
35 Closes a handle obtained by <tt>dio_open</tt>. Returns status code.
38 <sect>Reading and writing sectors<p>
40 The read and write functions are:
43 unsigned char __fastcall__ dio_read (dhandle_t handle,
48 This function will read the sector specified by <tt>sect_num</tt> into the memory
52 unsigned char __fastcall__ dio_write (dhandle_t handle,
57 This function will write the memory contents at buffer to the sector specified
58 by <tt>sect_num</tt>. No verify is performed.
61 unsigned char __fastcall__ dio_write_verify (dhandle_t handle,
66 This function will write the memory contents at buffer to the sector specified
67 by <tt>sect_num</tt>. A verification is performed.
70 Use the <tt><ref name="dio_query_sectsize" id="sectsize"></tt> function to query the size of a sector.
72 All these functions will return 0 for success and an OS specific error code in
76 <sect>Querying sector size<label id="sectsize"><p>
78 Some systems support multiple diskette formats which have different sector sizes.
79 The following function returns the sector size of the currently inserted disk:
82 sectsize_t __fastcall__ dio_query_sectsize(dhandle_t handle);
85 On the Atari platform, the sector size is handled specially. Please refer
86 to the DIO section in the <htmlurl url="atari.html" name="Atari">
87 specific platform documentation.
89 <sect>Converting sector numbers<p>
91 Since the read and write functions expect a sector number, for systems where
92 the sectors aren't addressed by a logical sector number (e.g. CBM drives),
93 there are 2 conversion functions. One of them converts a logical sector number
94 to a head/track/sector triple. The other conversion function works the other
98 unsigned char __fastcall__ dio_phys_to_log (dhandle_t handle,
99 const dio_phys_pos *physpos,
103 This function converts track/head/sector to logical sector number.
106 unsigned char __fastcall__ dio_log_to_phys (dhandle_t handle,
107 const _sectnum_t *sectnum,
108 dio_phys_pos *physpos);
111 This function converts a logical sector number to track/head/sector notation.
114 Note, that on systems which natively use logical sector numbers (e.g. Atari),
115 the conversion functions are dummies. They ignore head/track
116 (<tt>dio_phys_to_log</tt>) or return them as zero (<tt>dio_log_to_phys</tt>).
117 The logical sector number is returned as physical sector and vice versa.