Epson 8900 Series manual Parallel data timing sequence

The following figure shows the timing sequence for host-to-printer character-transfer operations. The table on the following page lists the timing requirements for the operation.

a	b		c	d	e	f	g	h
	▲	▲▲						▲▲
			▲
DATA1-8				valid data				valid data
STROBE-
BUSY
ACK-
		▲
reference
line
parallel data timing sequence

The reference points, a through h in the preceding figure, are keyed to the table on the following page and to the following character-transfer sequence.

1.The host writes a character to the parallel data lines (a). (The data stabilization time, a-b, must elapse before the transfer cycle can begin and the minimum data hold time, b-c, must elapse before the host can write a subsequent character.)

2.After writing the character to the interface, the host monitors the BUSY line to ensure that the printer is ready to receive a character. If BUSY is inactive, and the required data stabilization time has elapsed, the host activates STROBE- to begin the transfer cycle. The leading edge of STROBE- (b) clocks the character into the printer receive buffer and activates BUSY.

Communication Interfaces 10-11