Epson 8900 Series manual Host

The following figure shows a simplified block diagram of the printer receive buffer and the data path between the host and the print mechanism.

host

communication

interface

printer

receive print

buffer mech.

printer receive buffer and associated data path

The host transfers characters in the form of 7-bit or 8-bit data bytes, depending on which character set is selected. To ensure that no data is lost between the host and the printer, all data-transfer operations involve the following steps.

1.The host transfers characters via the communication interface into the printer receive buffer and then the printer transfers them at a fixed rate from the receive buffer to the print mechanism.

2.If the host-to-receive buffer transfer rate exceeds the buffer-to-print mechanism transfer rate, the receive buffer eventually approaches its capacity.

3.The printer signals the host to suspend data transfer operations as the printer continues to transfer characters at a fixed rate from the receive buffer to the print mechanism.

4.When the supply of characters in the receive buffer is sufficiently depleted, the printer signals the host that it is ready to receive additional data.

Communication Interfaces 10-5