It can be safely concluded that the DOS version of Metal Gear was badly tested before being released. Chock full of bugs, the worst ones being a bunch that block player progress.
-3 essential items don't appear in their respective rooms.
-1 essential item is acquired by defeating a certain boss, or rather, a pair of bosses. Only problem is those bosses disappear off the screen after a few seconds. Sometimes one of them remains on-screen, and you can even kill that one; only problem is leaving and returning to that area respawns the defeated boss and they both go back to the disappearing act.
-One room requires a particular access card number/level to enter its door... except that access card is in the room.
Does anyone know how to contact Charles Ernst, this version's developer? I'd like to ask him how the publisher overlooked how unfinished his game is.