DougDeMartinis Disk Editor dEd is a screen-oriented disk editor utility written in assembly language. It was originally conceived as a floppy disk editor, so the display is organized around individual sectors. It performs most of the functions of Patch, from Computerware, but is faster, more compact, and screen-oriented rather than line-oriented. Individual files or the disk itself (hard, floppy, ram) can be examined and changed, sectors can be written to an output file, and executable modules can be located, linked to and verified. With simple changes, it will run on any CoCo Level I OS-9 and possibly others (CoCo Level II OS-9). To use, type: dEd <pathlist> where <pathlist> is of the form: filename or dirname or /path/filename or /D0@ (edits entire disk) dEd will read in and display the first 256 bytes in the file (disk). This is Logical Sector Number (LSN) zero. You move through the file sector (LSN) by sector using the up and down arrow keys. The current LSN number is displayed in Hex and Decimal in the upper left corner of the screen. If the disk itself was accessed (by appending '@' to it's name when dEd was called), the LSN is the disk sector number. If an individual file is being editted, however, the LSN displayed refers to the file, not to the disk. All numbers requested by dEd must be in Hex format. All commands are accessed by simply pressing the desired key. Up/Down Arrows Display Next/Previous Sector (LSN) Each keypress moves the display to the next or previous 256 bytes. Auto-repeat allows skimming quickly through the file. To halt the key-repeat, type Control-W to pause the display, then hit any key. The LSN displayed represents the most-significant byte of the offset of the bytes from the start of the file (module), so byte number $1457 would be found in LSN $14 on row 50, column 7. A Command APPEND Current LSN to Output File This command writes the sector currently displayed to the file opened with the O command. Append is inactive unless an Output file has been created. This mode is useful for recovering files with unreadable sectors in them, as all the sectors before and after the crashed sector may be accessed and saved to a new file. Append also increments the display to the next LSN automatically to speed this process. At the end of a file, generally fewer than 256 bytes will be displayed, as the length of most files is not an even multiple of 256. The Append command will only write out the bytes that are displayed, and the display will remain on the same LSN. Pressing 'A' twice on the last LSN of a file results in it being written to the output file twice. C Command CLOSE Output File This command closes the file opened with the O command and removes the file name from the display, making Append inactive. D Command Diddle with the File Length This command displays the current file length, in Hex, then allows you to change it. This is potentially very dangerous (e.g. if you use it on loadable modules). If you just press <ENTER> at the prompt, you will be returned to the command mode (this is useful for just checking the file length). If you enter a valid length (number of BYTES, not sectors, in Hex), the file will be expanded or contracted to that length. This is useful for stripping the Control-Z's ($1A) off the end of files downloaded with the XModem protocol. Remember, the LENGTH of a file is 1 greater than the number of the last byte in the file (remember, counting from 0!) E Command EDIT the displayed Sector This is the heart of dEd. The cursor will appear over the first byte or character in the LSN. If it's over the BYTE, you can change the value by typing 2 new nibbles in Hex, e.g. 6c. The display will be updated and the cursor will move to the next BYTE. If the cursor is over the CHARACTER part of the display, you can change the value by typing a new ASCII character. Again, the display will be updated and the cursor will shift to the next character. You switch between the BYTE and CHAR modes at any time by hitting the <BREAK> key, as noted at the bottom of the display. You navigate through the sector to individual BYTEs or CHARs using the 4 Arrow keys. The Right and Left Arrows wrap the cursor around to the next or previous row on the display. The Up and Down Arrows wrap around from top to bottom and vice-versa. Once you are done Editting, pressing <ENTER> will exit the Edit mode, as noted at the bottom of the display. As with Zap, the sector is NOT written back to the disk unless the Write command is then used (unless in Expert mode). F Command FIND This searches the file for a given character or byte string You will be prompted with 'Find byte string $'. Enter a series of up to 16 Hex bytes, without spaces (you MUST enter leading zeroes for the numbers 00 - $0F) then press <ENTER>. The search begins at the start of the LSN currently displayed. If a string is located that EXACTLY matches the string you input, the LSN in which it is located will be displayed, with the first byte/character in the string highlighted. By pressing the <BREAK> key at the prompt, you can toggle between the BYTE and CHARACTER search modes. In the character mode, the prompt is 'Find char string: '. Enter up to 16 ASCII characters, then press <ENTER>. In this mode, dEd will locate any string that matches the one you input, regardless of the Upper/Lower case status of either string. As well, characters with bit 7 set (e.g. file names in directories) are treated as if bit 7 was clear. If no matching string is found, you are returned to the command prompt. If you enter an invalid character or byte string, a beep sounds and the same prompt is re-issued. If you just press <ENTER> at either prompt, you will be returned to the command mode. If you wish to abort a search in progress, just press the <BREAK> key. This will simulate a "string not found" and return you to the CMD: prompt. H (or '?') Command HELP This displays a Help screen. L Command LINK to a Module/LIST Modules If you are editting a file that consists of various executable modules merged together (e.g. OS9Boot), this command allows you to 'Link' to one of the modules. It will be treated as if it is an individual file, i.e. the start of the module will be displayed as LSN 0 and only THAT MODULE will be accessible for display and/or Editting. The LSN displayed is referenced to the MODULE, not to the main file or the disk. You will be prompted with 'Link to which Module? '. You may enter a valid name and press <ENTER>. If that module can be located AND if it's header information is correct, it will be 'Linked'. The top row of the display reflects this by displaying the module name and it's offset, in bytes, from the beginning of the main file. At the 'Link to which Module? ' prompt, if you just hit <ENTER>, all the valid modules and their offsets from the beginning of the main file as well as their lengths, in bytes Hex, will be Listed. Hitting any key after this redisplays the current LSN. The Link mode is useful for changing a given byte in a module using the offset one would use for Debug. For example, to permanently change the printer baud rate, you would call 'dEd /D0/OS9Boot'. Then hit 'L' for Link. At the prompt 'Link to which Module? ', Type P and hit <ENTER>. If P is in your OS9Boot file, the top row of the display will have MODULE: P and give the offset of it from the beginning of the OS9Boot file. Enter the Edit mode by hitting 'E' then use the arrows to move the cursor to byte number 27 (row 20, column 7). Type in the new value for the baud rate then hit <ENTER> to exit Edit mode. Hit 'W' to write the sector, then 'V' to verify the modules. If a module is linked, the 'Find' command only searches for strings in that module. N Command Find Next occurrence of String This is used in conjunction with the 'Find' command. Once a Hex byte or ASCII character string has been located with 'F', the next occurrence may be located by pressing 'N'. This search starts where the 'Find' search left off, IF the LSN hasn't changed since the string was initially located. If the LSN has changed, the search starts at the beginning of the current LSN. If the search is successful, the string will be highlighted, as with 'Find', otherwise you are returned to the command prompt, with a beep. O Command OPEN an Output File You will be prompted with 'OUTFILE: '. Type in a file name or path (that does not already exist) and press <ENTER>. A new file will be created and opened, with the name displayed on the second row of the screen. Individual sectors can be written to this file using the Append command. To abort the O Command, just press <ENTER> or <BREAK>. P Command Push an LSN onto the Sector Stack This pushes the current LSN onto a funtional Stack of sectors. The 'R' command then can remove (pull) them from the Stack in the reverse order (Last In, First Out) that they were pushed. Up to 16 LSN's can be saved on the Stack. This is very useful when trying to reconstruct a deleted file that was fragmented on the disk. By pushing each sector examined onto the Stack, you can retrace your steps backwards without having to remember the sector number of each sector along the way. Q Command QUIT dEd This exits dEd immediately. You should be sure to Write any Editted or Zapped sectors back to the disk before Quitting. R Command Remove an LSN from Sector Stack and Display This removes (pulls), from the Sector Stack, the last LSN that was pushed (with the 'P' command) and displays it. S Command SKIP to a given LSN You will be prompted with 'LSN=$ '. Type a sector number (in Hex) and press <ENTER>. That LSN will then be displayed, if possible. If the LSN entered is greater than the last LSN in the file, nothing will happen. U Command Unlink a Module This 'unlinks' a module that has previously been 'linked' using the 'L' command. The first sector in the file (LSN 0) is displayed. Using this command when no module has been linked has no effect. V Command VERIFY All Modules This command calculates and writes a new CRC value for EACH module in a fale. It must be used after Editting executable modules or they will not be loadable. Verify is terminated if an error is located in the header of a module, but each module is verified individually and the CRC is rewritten to each before moving to the next module in a file, so modules in front of one with an error will be verified. W Command WRITE the Sector displayed to the Disk WARNING!!! This command can be very dangerous to the well- being of your disk data. It writes the sector displayed back to the disk (at the same location from whence it came, but not necessarily with the same information, hence the danger). After Zapping or Editting a sector, you must use this command to make the changes on the disk (unless you're in the Expert mode). Because you can effectively maim your data with this command, you will be prompted with 'Are you sure (Y/N)? '. If you hit any key other than 'Y' (or 'y') the Write command will be aborted. Otherwise the sector will be written, with the display advising you that dEd is 'Writing Sector...'. On a hard disk or RAM disk, this is very quick. X Command EXPERT Mode This command is potentially the most dangerous of all. It should be used only by those who are very brave (fools?) or those who never make mistakes. In this mode, any sectors changed by Edit or Zap will be automatically written to the disk. The Write command is not needed, and is inactivated in the Expert mode. Any errors made during Edit or Zap WILL be transferred to the disk, making this mode very good for crashing directories, etc. Having noted this, there is one route of escape from errors made in this mode. After Editting or Zapping a sector, the sector is not actually written back to the disk until after Edit or Zap is exitted and the next command is issued (i.e. the next Command Key is pressed). If you hit Shift-BREAK , before hitting any other Command Key, the automatic Write will not occur. You must type Shift-BREAK before any other command or the sector will be written to the disk. This is a one-time escape, so any further errors made will require hitting the Shift-BREAK key again at the appropriate time to avoid writing the bad sector to the disk. Unless you fully understand the OS-9 disk structure (or enjoy toying with the life of your data), this mode should probably be avoided. It is entered after responding with a 'Y' or 'y' to the 'Are you sure (Y/N)?' prompt, and the display advises you that you are in this mode. The 'X' command is a toggle switch, so to exit Expert mode, just hit 'X' again and the 'Expert Mode' message will be erased. Z Command ZAP the displayed Sector You will be prompted with 'Zap Byte: ' or 'Zap Char: '. Enter either a Hex byte (e.g. 6c) or an ASCII character (e.g. $) and press <ENTER>. That byte or character will be written to the ENTIRE SECTOR. You can toggle between the BYTE/CHAR modes by hitting the <BREAK> key. In the CHAR mode, hitting ALT-Char then <ENTER> will Zap the sector with that char with bit 7 set. Unless you're in the Expert mode, only the buffer will be Zapped with the Zap command. To put this Zapped sector on the disk, you must use the Write command. If you decide not to Zap the sector, just hit <ENTER> without first entering a byte or character. You can redisplay a sector that has been Zapped, but not Written back to the disk, by going to the next LSN using the Up Arrow, then returning to the original LSN with the Down Arrow (again, provided you're not in the Expert mode). $ Command Fork a SHELL A new Shell is forked to allow access to OS-9 without terminating dEd. To return to dEd, press Ctrl-BREAK (ESC). <CR> Command Clean up screen display Pressing <ENTER> at the CMD: prompt will clear and re-write the screen which may have been trashed by an error. Current editing to the displayed sector is not lost or written. This command only resets the screen display.