DISK DIRECTORY HEADER¢---------------------¢¢Document version II¢¢May 1993¢¢Written by John Foskett¢¢¢¢Looking at the directory of many commercial disks, it can be seen that in many cases the directory contains some form of header which can be viewed and read by DOS. The header is normally stored at the top of the directory in sector 361 and usually consists of characters which are quite illegal for file name use such as inverse video or control characters, therefore it is not sufficient to simply SAVE a null file to disk. A disk sector editor can be used to create a header and write it into the first directory sector (sector 361) but this can prove confusing and hence inconvenient and time consuming. The answer to the problem was to write a small program to create the header using a more user friendly means and so the 'Disk Directory Header' was born.¢ The Directory Header is capable of creating a header consisting of upto eight lines (that is completely filling sector 361 if required), each line can consist of upto eleven characters (i.e. normal file name length).¢*¢THE SCREEN¢¢Apart from the title at the top, the screen is split into two sections. The top section is used to display the header as it is being created line by line, exactly as it will appear within the disks directory. The lower section is used for creating each line and to display the various menus and comments.¢*¢USING THE DIRECTORY HEADER¢¢Each line is entered at the prompt thus: ">" together with the instruction "Please enter line X" (where X is the current line number). Editing a line is achieved by using the DELETE BACK SPACE key, the left/right arrow keys in the usual way with CONTROL and ESCAPE to exit.¢ Upon pressing RETURN to enter the line, a menu is displayed which again allows ESCAPE to exit. "C" is pressed to continue with the next line or "E" is pressed to end the header creation and to pass on to the next stage.¢*¢PREPARE DISK¢¢Prepare disk allows a disk to be formatted in either single or enhanced density, ESCAPE again is used to exit. "S" is pressed to select single density or "E" is pressed for enhanced density. After selecting, a cautionary comment is displayed which requires "Y" to be pressed to continue. Any other key will return back to the previous stage to select the format density.¢ Upon pressing "Y", the disk which is currently in drive #1 is formatted and the header written into the disks directory (sector 361).¢ After the header has been written, the option to write the DOS.SYS file is given and upon pressing "Y" the DOS.SYS file is written and locked.¢ Whether or not the DOS.SYS file is written to disk, the option to prepare another disk is presented. Pressing "Y" will allow the format density for this disk to be selected. Any other key will exit.¢*¢TECHNICAL DETAILS¢¢A small VBI routine controls the type of characters used at any time by using one of the unused locations in page zero, that is location 203. When this location contains a zero, only uppercase characters can be used. This cancels any accidental press of the CAPS key or the inverse video key when selecting from the various menus. When memory location 203 contains a non-zero value, any character can be used, this is the case when entering line details.¢ Two further locations in page zero are used, (204 and 205) which are used to store the status of the key board from locations 694 and 702 respectively and restoring them after selecting from the menu. This is to ensure that if for example inverse video characters were being used then they will be returned for the next line after pressing "C" to continue from the menu.¢ All possible errors are trapped and are displayed on screen together with an appropriate message. RETURN must be pressed to continue.¢
