APPENDIX B

DOS ERROR MESSAGES

The following error messages are returned through the DS and DS$ variables. The DS variable contains just the error number and the DS$ variable contains the error number, the error messages and any corresponding track and sector number.

Note: Error message numbers less than 20 should be ignored with the exception of 01, which gives information about the number of files scratched with the SCRATCH command.

ERROR NUMBER	ERROR MESSAGE AND DESCRIPTION
20:	READ ERROR (block header not found) The disk controller is unable to locate the header of the requested data block. Caused by an illegal sector number, or the header has been destroyed.
21:	READ ERROR (no sync character) The disk controller is unable to detect a sync mark on the desired track. Caused by misalignment of the read/write head, no diskette is present, or unformatted or improperly seated diskette. Can also indicate a hardware failure.
22:	READ ERROR (data block not present) The disk controller has been requested to read or verify a data block that was not properly written. This error occurs in conjunction with the BLOCK commands and indicates an illegal track and/or sector request.
23:	READ ERROR (checksum error in data block) This error message indicates there is an error in one or more of the data bytes. The data has been read into the DOS memory, but the checksum over the data is in error. This message may also indicate hardware grounding problems.
24:	READ ERROR (byte decoding error) The data or header has been read into the DOS memory but a hardware error has been created due to an invalid bit pattern in the data byte. This message may also indicate grounding problems.
25:	WRITE ERROR (write-verify error) This message is generated if the controller detects a mismatch between the written data and the data in DOS memory.
26:	WRITE PROTECT ON This message is generated when the controller has been requested to write a data block while the write protect switch is depressed. This is caused by using a diskette with a write protect tab over the notch.
27:	READ ERROR (checksum error in header) This message is generated when a checksum error had been detected in the header of the requested data block. The block has not been read into DOS memory.
28:	WRITE ERROR (long data block) This error message is generated when a data block is too long and overwrites the sync mark of the next header.
29:	DISK ID MISMATCH This message is generated when the controller has been requested to access a diskette which has not been initialized. The message can also occur if a diskette has a bad header.
30:	SYNTAX ERROR (general syntax) The DOS cannot interpret the command sent to the command channel. Typically, this is caused by an illegal number of file names, or patterns are illegally used. For example, file names appear on the left side of the COPY command.
31:	SYNTAX ERROR (invalid command) The DOS does not recognize the command. The command must start in the first position.
32:	SYNTAX ERROR (long line) The command sent is longer than 58 characters. Use abbreviated disk commands.
33:	SYNTAX ERROR (invalid file name) Pattern matching is invalidly used in the OPEN or SAVE command. Spell out the file name.
34:	SYNTAX ERROR (no file given) The file name was left out of the command or the DOS does not recognize it as such. Typically, a colon {:} has been left out of the command.
39:	SYNTAX ERROR (invalid command) This error may result if the command sent to the command channel (secondary address 15) is unrecognized by the DOS.
50:	RECORD NOT PRESENT Result of disk reading past the last record through INPUT# or GET# commands. This message will also occur after positioning to a record beyond the end-of-file in a relative file. If the intent is to expand the file by adding the new record (with a PRINT# command), the error message may be ignored. INPUT# or GET# should not be attempted after this error is detected without first repositioning.
51:	OVERFLOW IN RECORD PRINT# statement exceeds record boundery. Information is truncated. Since the carriage return which is sent as a record terminator is counted in the record size, this message will occur if the total of characters in the record (including the final carriage return) exceeds the defined size of the record.
52:	FILE TOO LARGE Record position within a relative file indicates that disk overflow will result.
60:	WRITE FILE OPEN This message is generated when a write file that has not been closed is being opened for reading.
61:	FILE NOT OPEN This message is generated when a file is being accessed that has not been opened in the DOS. Sometimes, in this case, a message is not generated; the request is simply ignored.
62:	FILE NOT FOUND The requested file does not exist on the indicated drive.
63:	FILE EXISTS The file name of the file being created already exists on the diskette.
64:	FILE TYPE MISMATCH The requested file access is not possible using files of the type named. Reread the chapter covering that file type.
65:	NO BLOCK Occurs in conjunction with Block Allocation. The sector you tried to allocated is already allocated. The track and sector numbers returned are the next higher track and sector available. If the track number returned zero (0), all remaining sectors are full. If the diskette is not full yet, try a lower track and sector.
66:	ILLEGAL TRACK AND SECTOR The DOS has attempted to access a track or block which does not exist in the format being used. This may indicate a problem reading the pointer of the next block.
67:	ILLEGAL SYSTEM T OR S This special error message indicates an illegal system track or sector.
70:	NO CHANNEL (available) The requested channel is not available, or all channels are in use. A maximum of five buffers are available for use. A sequential file requires two buffers; a relative file requires three buffers; and the error/command channel requires one buffer. You may use any combination of those as long as the combination does not exceed five buffers.
71:	DIRECTORY ERROR The BAM (Block Availability Map) on the diskette does not match the copy on disk memory. To correct, initialize the diskette.
72:	DISK FULL Either the blocks on the diskette are used or the directory is at its entry limit. DISK FULL is sent when two blocks are still available on the diskette, in order to allow the current file to be closed.
73:	DOS MISMATCH (VERSION NUMBER) DOS 1 and 2 are read compatible but not write compatible. Disks may be interchangeably read with either DOS, but a disk formatted on one version cannot be written upon with the other version, because the format is different. This error is displayed whenever an attempt is made to write upon a disk which has been formatted in a non-compatible format. This message will also appear after power up and is not an error in this case.
74:	DRIVE NOT READY An attempt has been made to access the disk drive without any inserted diskette; or the drive lever or door is open.