XDIR's interrupt 13h handling routine as originally published inadvertently altered the flags register passed back from the BIOS, causing certain diskette operations (such as the DOS FORMAT command) to mysteriously fail. Many thanks to Charles Copeland and John Mullis, who first notified me of the problem and suggested a cure. The second problem was recognized and reported by several readers. XDIR employed the auxiliary timer interrupt (interrupt 1Ch) when it should have attached itself to the primary one (interrupt 8). Although the effects of this probably never showed up on your system, the potential for a crash was there since XDIR sent its own EOI signal to the 8259. The BIOS interrupt 8 handler sends an EOI immediately after regaining control from interrupt 1Ch, so any interrupt being serviced when XDIR's timer routine stepped in was in danger of being ended prematurely. In retrospect, the best solution is to avoid the timer interrupt altogether. The revised XDIR relocates the code responsible for checking the internal DOS flag and popping up the window inside the keyboard interrupt routine. As we often point out when we publish a TSR utility, there are some applications which will be inherently incompatible with it. Some readers have reported trouble using XDIR with QuickBASIC 2.0. QuickBASIC takes over interrupt 9 to detect the press of certain key combinations not recognized by the BIOS. In such situations, the only answer is to take the Sidekick approach of monitoring the interrupt 9 vector and grabbing it back if another program steals it. That violates the ground rules for well-behaved TSR's, though, and renders the utility incompatible with Sidekick. My apologies to anyone inconvenienced by XDIR as it was originally published. These utilities are tested thoroughly by their respective authors, then examined further by the staff of PC Magazine prior to publication. The charter of Programming/Utilities is to provide useful programs that illustrate in their own way programming tactics and principles. Watch for a slate of good ones appearing in coming months, including one that removes TSR's from memory. And sincerest thanks to the many readers who follow the magazine closely, with pen in hand ready to offer opinions, comments, and suggestions. Jeff Prosise