Filled by LIST_DRAWN: record numbers, then $FF. While SORT_AND_DRAW works through the list it sets bit 7 of each entry as that object is drawn, so the list also says what is still to do.

48 bytes: Knight Lore's size, for its forty records. Pentagram has 54, so a turn that listed more than 47 objects would write its later entries and the $FF over the start of SORT_AND_DRAW. The fullest room (87) builds 43 records from the directory, and lists 45 on arrival. Watched in the emulator: with two collectables staged into it the list reached 47 and the game ran on for 300 turns; with three it reached 48, the $FF landed on SORT_AND_DRAW's first byte as RST $38 -- which turns interrupts on -- frame interrupts then pushed onto sprite data mid-draw, and the game hung; with five, a hang after six turns. See the bugs page.