6530 Programmer's Guide

Overview
6530 Programmer’s Guide 1-5
6530 Display
Memory
Organization
A portion of the 6530 memory is reserved for storing data that can be
shown on the screen. This includes displayable (graphics) characters
entered from the keyboard or received from the host.
Note The message/status and error lines are handled separately.
Enough memory is allocated to fill the screen several times over. Using
various cursor or display control keys, the user can select which portion
of memory actually appears on the screen. How 6530 display memory is
organized and accessed depends on the mode of operation selected.
Conversational Mode Memory Organization
Display memory in conversational mode is organized as one continuous
area, similar to a roll of paper. Only 24 contiguous lines of display
memory can appear on the screen at one time.
The user or your application can move the cursor around and roll display
memory up or down on the screen. Information rolled off the top or
bottom of the screen continues to be stored in display memory until all the
available display memory lines are used. At this point, an attempt to move
the cursor past the last line of memory causes a scroll operation to occur.
The scroll operation deletes the first line of display memory, moves all
remaining memory lines up one line, and inserts a new blank line at the
bottom of display memory
Chapter 2 provides more details about display memory and cursor control
in conversational mode.
Block Mode Memory Organization
Display memory in block mode is divided into logical pages, each
consisting of 24 lines. The maximum number of pages that can be
allocated depends on the number of fields defined when protect submode
is used.
Only one page can be displayed at a time, and the screen display cannot
cross page boundaries, so rolling operations are disabled. Your
application program controls which page is displayed. Typically, the user
requests a new page to be displayed through one of the function keys.