The Hobbit (v1.0): Routine at 7DFB

The entry at 7DFB (from 7DB6) supplies the verb GO ($30 class) for a bare direction; the entry at 7DFD handles verbs typed by the player.

If a verb arrives when a command has already been started and there has been no AND, the parser backtracks: the state saved by the last AND (7DD5) is restored and the AND is reinterpreted as THEN, splitting the line into two commands.

Otherwise the verb must be allowed here (bit 1 of E). It is stored at offset 0 of the frame (7FDE). GO and RUN look ahead (from 7E31) past any adverbs: if the next word is a direction, the verb is dropped and the direction stored as the particle, so that 'go north' and 'north' produce the same frame.

The entry at 7DFB (from 7DB6) supplies the verb GO ($30 class) for a bare direction; the entry at 7DFD handles verbs typed by the player. If a verb arrives when a command has already been started and there has been no AND, the parser backtracks: the state saved by the last AND (7DD5) is restored and the AND is reinterpreted as THEN, splitting the line into two commands. Otherwise the verb must be allowed here (bit 1 of E). It is stored at offset 0 of the frame (7FDE). GO and RUN look ahead (from 7E31) past any adverbs: if the next word is a direction, the verb is dropped and the direction stored as the particle, so that 'go north' and 'north' produce the same frame.
7DFB	LD D,$30	Class of GO (for a bare direction)
7DFD	BIT 3,E	VERB: has there just been an AND?
7DFF	JR NZ,$7E1F	Yes: a new command after AND is fine
7E01	CALL $7CBB	Inside a quotation?
7E04	JR NZ,$7E1F	Yes: accept it
7E06	LD HL,($7C3E)	A second verb without AND: backtrack to the last AND...
7E09	LD ($B5CD),HL	A second verb without AND: backtrack to the last AND...
7E0C	LD D,$B0	...and treat it as THEN
7E0E	LD A,($7C40)	Restore the state saved at the AND
7E11	LD E,A
7E12	LD A,($7C43)
7E15	LD ($B5F7),A
7E18	LD IY,($7C41)
7E1C	JP $7CC4	Close the frame and start a new one
7E1F	CALL $7F29	A verb cancels ALL
7E22	BIT 1,E	Is a verb allowed here?
7E24	JP Z,$7FF3	No: syntax error
7E27	BIT 0,E	Is this a GO followed by a direction?
7E29	JR Z,$7E31	No: look ahead
7E2B	CALL $7FDE	Store the verb in the frame
7E2E	JP $7C7E	Next noun phrase
7E31	PUSH DE	Look ahead past any adverbs...
7E32	PUSH BC
7E33	LD HL,($B5CD)
7E36	PUSH HL
7E37	CALL $7F3D
7E3A	CP $00
7E3C	JR Z,$7E37
7E3E	SET 0,E
7E40	CP $20	...is the next word a direction?
7E42	JR Z,$7E4C	Yes
7E44	POP HL	No: rewind and store the verb normally
7E45	LD ($B5CD),HL
7E48	POP BC
7E49	POP DE
7E4A	JR $7E2B
7E4C	CALL $7FDE	Store GO as the verb...
7E4F	POP HL
7E50	POP BC
7E51	POP HL
7E52	LD L,$02	...and the direction at offset 2
7E54	CALL $7FE2	...and the direction at offset 2
7E57	JP $7C7E	Next noun phrase