6530 Programmer's Guide

Overview
1-4
6530 Programmer’s Guide
In block mode, the 6530 displays characters typed on the keyboard and
stores them in display memory. The 6530 does not transmit any data until
the host application issues a read request. Thus, a user can enter multiple
lines of data or even a complete screen between transfers to the host. The
6530 transmits data as a block. A block can be a full screen or page of
data. Each block begins with a start of text (STX) or start of header
(SOH) character and is terminated by an end of text (ETX) and
longitudinal redundancy check (LRC) character.
Block mode has two submodes:
Nonprotect (default). The user can position the cursor anywhere on
the screen and enter any type of data.
Protect. Your application program can divide the screen into fields
with assigned video and data attributes.
Chapter 3 describes the details of block mode operation.