Volex TTX2000 S Issue 1.2: Routine at 0280

0280: hamming_decode_hl: Hamming 8/4 decode the byte at address in HL and return it in B.

Used by the routines at NMI_ISR, decode_magazine_number and decode_packet_number.
hamming_decode_hl	0280	LD C,(HL)	Read byte at address in HL into C.
	0281	PUSH HL	Add to hamming_decode_table_pointer to get offset in table.
	0282	LD HL,(hamming_decode_table_pointer)
	0285	LD B,$00
	0287	ADD HL,BC
	0288	LD B,(HL)	Return decoded byte from table in B.
	0289	POP HL	Return decoded byte from table in B.
exit_pointer_RET	028A	RET	This RET instruction is used to return from menus, vectored through exit_pointer.