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07917: THE 'GO SUB' COMMAND ROUTINE
The address of this routine is found in the parameter table.
The present value of PPC and the incremented value of SUBPPC are stored on the GO SUB stack.
GO_SUB 07917 POP DE Save the address - STMT_RET.
07918 LD H,(IY+13) Fetch the statement number (SUBPPC) and increment it.
07921 INC H
07922 EX (SP),HL Exchange the 'error address' with the statement number.
07923 INC SP Reclaim the use of a location.
07924 LD BC,(23621) Next save the present line number (PPC).
07928 PUSH BC
07929 PUSH HL Return the 'error address' to the machine stack and reset ERR-SP to point to it.
07930 LD (23613),SP
07934 PUSH DE Return the address STMT_RET.
07935 CALL GO_TO Now set NEWPPC and NSPPC to the required values.
07938 LD BC,20 But before making the jump make a test for room.
This routine continues into TEST_ROOM.
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