WARNING: This section is up to date as of November 21, 2015. Zachtronics has explicitly warned that any “implementation-defined” or “undefined” behaviors may change in future versions of TIS-100.
Commas are treated like whitespace.
Lines containing only comments and whitespace are ignored (not treated as NOPs), do not count toward relative offsets for the JRO instruction, and do not add to your instruction count for scoring purposes. Nodes containing only comments and whitespace remain in the IDLE state and do not add to your node count for scoring purposes.
Numbers and punctuation (except for ':', ' ', '#', '!', ',', and '@') are valid characters in label names.
Nodes are numbered starting at 0 for the top left node and continuing left to right, top to bottom, skipping communication failures and Stack Memory Nodes. The '@' character is used in the save files to indicate the start of each node’s code, and cannot be entered in the game’s interface.
Basic Execution Nodes hold 15 lines of up to 18 characters each. The longest possible instruction is XX:MOV RIGHT RIGHT.
Stack Memory Nodes hold up to 15 values.
Results are clipped to +/- 999 and do not wrap around. Integer literals are clipped before evaluation; i.e. ADD 1000 behaves the same as ADD 999, even when ACC contains a negative value.
Using the LAST pseudo-port when its value is N/A (before it has been initialized with ANY) has the same effect as using NIL.
A JRO forward past the end of a program behaves the same as a JMP to the last instruction. A JRO backward past the beginning of a program behaves the same as a JMP to the first instruction.
Simultaneous reads from a Basic Execution Node that is writing to ANY are resolved in the following priority order. The other destination nodes will block.
Simultaneous reads from a Stack Memory Node are resolved in the following priority order. The other destination nodes will block. If a Stack Memory Node is read from and written to on the same cycle, the read is performed before the write(s).
UPLEFTRIGHTDOWNSimultaneous writes to a Basic Execution Node that is reading from ANY are resolved in the following priority order. The other source nodes will block.
Simultaneous writes to a Stack Memory Node are all completed on the same cycle. The values are written to the stack in the following order after any read operation for that cycle is resolved.
LEFTRIGHTUPDOWNWrites with a color value greater than 4 are ignored, but still advance the cursor. Writes with a negative color value terminate the command sequence.
Writes beyond the right or bottom edge of the display are ignored.
Since any negative value terminates the command sequence, it is not possible to specify X or Y coordinates beyond the left or top edges of the display.