A surgical stapling apparatus (stapler) is provided. A tool assembly includesfirst andsecond jaw members. A cartridge assembly includes an actuation sled and aslide. A drivemember having a working end is configured to translate through the toolassembly when the firstand second jaw members are in a closed configuration. A lock assemblyincluding a latch ismovable from a locked position to an unlocked position. The latch is urged tothe lockedposition to engage the working end to prevent distal translation of the drivemember through thetool assembly. The slide is configured to move the latch from the lockedposition to theunlocked position upon installation of an unspent cartridge assembly onto thefirst jaw member.The slide is movable by the drive member upon actuation of the staplingapparatus to allow thelatch to move back to the locked position.
