Volex TTX2000 S Issue 1.2: Routine at 1938

1938: block_downloaded: See if there are undownloaded blocks remaining.

Used by the routine at telesoftware_main.
block_downloaded	1938	LD HL,(page_receive_buffer_pointer)	Set HL to page_receive_buffer_pointer + 927 (row 23, column 7).
	193B	LD DE,$039F
	193E	ADD HL,DE
	193F	LD A,(HL)	Load low 6 bits of byte into DE (block number).
	1940	AND $3F
	1942	LD E,A
	1943	LD D,$00
	1945	LD HL,$4800	Add to $4800 to get offset in map of received blocks.
	1948	ADD HL,DE	Add to $4800 to get offset in map of received blocks.
	1949	LD (HL),$3F	Store $3F at offset.
	194B	XOR A	Decrement blocks_remaining.
	194C	LD HL,blocks_remaining
	194F	DEC (HL)
	1950	JR NZ,block_downloaded_0	If blocks_remaining is zero return $00 else return $01.
	1952	INC A
block_downloaded_0	1953	RET