HP 706C, 710F, 710E, 708D, 708E, 706D, 708C, 706A COMPUTER-TO-PRINT MASTER-TO-PRINTER Communication

￿￿￿￿)￿￿%)￿￿￿￿#￿￿￿￿#￿￿￿￿￿

COMPUTER-TO-PRINT MASTER-TO-PRINTER COMMUNICATION

When a computer transmits data to a printer through a Print Master computer port, the data is received and stored in the buffer which in turn retransmits it to the printer through a printer port. During transmission, after the buffer fills to where there is only 4K of memory remaining, Print Master will make the computer port's CTS (Clear-to-Send) line low (negative voltage) or send an XOFF, signaling the computer that it cannot accept any more data. (However, in reality it can accept another 4K before overflowing the buffer.)

When the buffer empties to where more than 4K remains (Print Master's buffer outputs 4K blocks of data), Print Master will make the CTS (Clear-To-Send) line high (positive voltage) or send an XON, signaling the computer that it can accept more data.

When Print Master retransmits the data to the printer and the printer cannot receive any more data, the unit will expect to see a low on the DTR (Data Terminal Ready) line or receive an XOFF. When the printer can receive more data, Print Master will expect to see a high on the DTR line or receive an XON.

36