Disk Basic Summary In addition to the capabilities of Extended Color BASIC, Color Disk BASIC adds the following. -------------------------------------------------------------------------- Disk management commands BACKUP n TO m Copy all files from one disk to another BACKUP n BACKUP a disk using only a single disk drive COPY file1 TO file2 Make a duplicate of a file DIR n List the files that are on the disk DRIVE n Use drive n as the default DSKINIn Initialize (format) a disk KILL file Delete a file from the disk LOAD file,R Load a program, and optionally start it running LOADM file,offset Load a machine-code program, shifting by offset MERGE file,R Load an ASCII program without clearing the old one RENAME file1 TO file2 Change the name of a file RUN file,R Load a program, and optionally start it running SAVE file,A Save a program, optionally in ASCII SAVEM file,a1,a2,ax Save a machine-code program, from a1 to a2, exec at ax VERIFY ON Double-check all writes to the disk VERIFY OFF Don't double-check Programming commands FILES max_f,size Reserve buffers for open files FREE(n) Returns the number of free granules (2304 bytes each) UNLOAD n Close all open files on drive n DSKI$ n,t,s,v1$,v2$ Read track t sector s into v1$ and v2$ DSKO$ n,t,s,v1$,v2$ Write track t sector s from v1$ and v2$ OPEN "I",f,file Open a file for sequential input (ie: INPUT) OPEN "O",f,file Open a file for sequential output (ie: PRINT/WRITE) OPEN "D",f,file,len Open a file for direct access; (ie: GET/PUT); record length len is optional CLOSE #f Close a file Sequential file commands EOF(f) Returns true if file f has been read to the end INPUT #f, var,... Read variables from a file LINE INPUT #f,var$ Read an entire line from a file into a string variable WRITE #f,values Write values to file, with commas, strings in quotes,... PRINT #f,values Write values to file, just as PRINT would display them PRINT #f,USING f$;values Formatted printing; many options for f$ Direct-access file commands FIELD #f, size AS v$,... Give variable names to parts of the file buffer RSET v$ = value$ Fill in a named part of the file buffer, right-justified LSET v$ = value$ Fill in ..., left justified PUT #f,r Write the buffer to record r GET #f,r Read record r into the buffer CVN(var$) Make a number out of a binary string MKN$(num) Make a binary string out of a number LOC(f) Return the current record number in the buffer LOF(f) Return the highest record number in the file In all cases, f is a file number, n and m are drive numbers, file is a filename, and dollar signs signify variables that must be string-variables. Note that filenames must be either string variables or string constants in quotes. Upper-case words are keywords, lower-case words are supplied by the user. Special file numbers are -2=printer -1=cassette and 0=screen ------------------------------------------------------------------------ Syntax for a filename, in BNF. (Things in square brackets are optional, the vertical bar separates alternatives, angle brackets surround nonterminals, and uppercase words denote single-letter constants.) ::= [(DOT|SLASH) ] [COLON ] The name can be up to eight characters long, and cannot include a dot, slash, colon, or zero. The extension can be up to three characters long, and also cannot include those four characters. The drive number is a single digit, from zero up to the highest drive on your system. ------------------------------------------------------------------------ There is one documented subroutine in the Disk BASIC ROM that you can use to access the disk. Its address is stored at $C004 and $C005, so you jump to it using indirection: JSR [$C004] . Before calling that, you should load the X register with the address of a data structure that describes what you want to do. The examples in the manual always load this address from locations $C006 and $C007. I have not tried using this, so I don't know it will work if you put your structure anyplace else. This data structure is seven bytes long: 1 byte op code (0 - 3) 1 byte drive number (0 - 3) 1 byte track number (0 - 34) 1 byte sector number (1 - 18) 2 bytes address of 128-byte data buffer 1 byte error code Op codes are either 0 (restore to track 0), 1 (no op), 2 (read sector), or 3 (write sector). Bits in the error code are defined as follows (since the labels match those in the 1771 data sheet, I assume it is just the 1771 status code being returned, and have taken the much more complete descriptions from that data sheet). Note that some of the bits have different meanings based on which command caused them to be set. 7 Not Ready This bit, when set, indicates that the disk drive is not ready to perform a read or write operation. When reset it indicates that the drive is ready. Thus, this bit is an inverted copy of the READY input signal to the 1771 from the disk drive, and is logically ORed with the *MR signal 6 Record Type/Write Protect On a Read command, this bit is used in conjunction with Bit 5 to indicate the type of data address mark that was read. On a Write command, this bit indicates that the diskette was write protected. 5 Record Type/Write Fault/Head Loaded On a Read command, this bit in conjunction with Bit 6 indicates the type of data address mark that was read. On a Write command, this bit indicates that the write fault input from the disk drive was detected: it is thus an inverted copy of the *WF input signal. On a Restore command, this bit indicates that the read/write head is loaded against the diskette surface. This bit is thus the logical AND of the HLD and HLT signals. 4 Record Not Found/Seek Error On Read or Write command, this bit indicates that the desired track and sector were not found. On a Restore command, this bit indicates that the designated track could not be verified. This bit is reset to 0 whenever a new command is loaded. 3 CRC error On a Read or Write command, if Bit 4 is also set, then this bit indicates that an error was found in one or more ID fields; otherwise, it indicates an error in a data field. On a Restore command, this bit indicates that one or more CRC errors were encountered on a track verification operation. This bit is reset to 0 whenever a new command is loaded. 2 Lost Data/Track 00 On a Read or Write command, this bit indicates that the microprocessor did not respond to the Data Request (DRQ) within one byte time and that a byte of data was subsequently lost. On a Restore command, this bit indicates that the read/ write head is positioned over track 0. This bit is thus an inverted copy of the *TR00 input to the 1771. 1 Data Request/Index On a Read or Write command, this bit is a copy of the DRQ output signal. When set, it indicates that the Data register is full on a read operation or empty on a write operation. On a Restore command, this bit indicates that an index mark was detected on the diskette. This bit is thus an inverted copy of the *IP input to the 1771. 0 Busy When set, this bit indicates that a command is currently being executed. This bit is reset when a command is completed and thus indicates that the 1771 is available to execute another command. The disk control routine modifies the contents of only the condition code register. Finally, note that you can force the drive motor to turn off by writing a zero into address $FF40. This probably also means you could force the motor on by writing non-zero there, but the documentation doesn't explain which bits to what. Disk Basic Error Codes: ---------------------- Err Description (No) /0 Division by zero AE File already exists (33) AO Attempt to open a data file that is already open BR Bad record number (27) BS Bad subscript CN Cannot continue DD Attempt to redimension an array DF Disk full (28) DN Drive number or device number error DS Direct statement ER Write or input past end of record (direct access only) (37) FC Illegal function call FD Bad file data FM Bad file mode FN Bad filename (31) FO Field overflow (34) FS Bad file structure (32) HP High-resolution print error (Color Computer 3 only) HR High-resolution graphics error (Color Computer 3only) ID Illegal direct statement IE Input past end of file IO Input/output error LS String too long NE Cannot find the disk file (26) NF NEXT without FOR NO File not open OB Out of buffer space (29) OD Out of data OM Out of memory OS Out of string space OV Overflow RG RETURN without GOSUB SE Set to non-fielded string (35) SN Syntax error ST String formula too complex TM Type mismatch UL Undefined line VF Verification (36) WP Write-protected disk (30)