6530 Programmer's Guide

Conversational Mode Operation
2-10
6530 Programmer’s Guide
Page Up (Esc V)
The Esc V sequence displays the previous 24 lines of display memory on
the screen. When the first line of display memory is on the screen, further
Esc V sequences are ignored. The cursor remains in the same relative
position.
Page Down (Esc U)
The Esc U sequence displays the next 24 lines of display memory on the
screen. If there are less than 24 lines remaining to the end of memory, the
memory lines are rolled up enough rows to display the remaining lines.
When the last line of display memory is on the screen, further Esc U
sequences are ignored. The cursor remains in the same relative position.
Display Page (Esc ;)
The Esc ; sequence displays either page 0 or page 1 on the screen. The
sequence requires one parameter, which is an ASCII character
immediately following the Esc ;. The character can be either a space
(20H) to represent page 0 or an ! (21H) to represent page 1. If any other
character is used, the 6530 ignores the escape sequence and the page
number remains unchanged.
Selecting page 0 displays a blank screen (except for the status line) and
locks the keyboard. However, it does not alter the contents of display
memory. Your application program can write to page 1 (normal display
memory) while displaying page 0. This is useful for preventing video
flash, which can occur if your program simultaneously displays and
writes video attributes to the same page. Selecting page 1 returns the
contents of display memory to the screen.
Clear Display
Memory
This group of escape sequences clears all or parts of display memory.
Clear Memory to Spaces (Esc I)
The Esc I sequence blank-fills the entire display memory regardless of
which portion is currently displayed. Immediately following the
operation, the cursor is placed in the home position on the screen.
Erase to End of Memory (Esc J)
The Esc J sequence blank-fills display memory starting from the current
cursor position to the end of display memory. The position of the cursor
is not altered by this operation.