# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1425600824 -3600
# Node ID 4ba74d41cfbaafb18778849f764c5601e3b78533
# Parent  e30a75c4b469c13aaeb56f2b0486cb255d60957b
Added region blanking and display suspend notes.

diff -r e30a75c4b469 -r 4ba74d41cfba ULA.txt
--- a/ULA.txt	Fri Mar 06 01:13:10 2015 +0100
+++ b/ULA.txt	Fri Mar 06 01:13:44 2015 +0100
@@ -359,8 +359,15 @@
 bottom 6 lines blank.
 
 See the description of the display suspend enhancement for a more efficient
-way of blanking lines whilst allowing the CPU to perform useful work during
-the blanking period.
+way of blanking lines than merely blanking the palette whilst allowing the CPU
+to perform useful work during the blanking period.
+
+To control the blanking or suspending of lines at the top and bottom of the
+display, a memory location could be dedicated to the task: the upper 4 bits
+could define a blanking region of up to 16 lines at the top of the screen,
+whereas the lower 4 bits could define such a region at the bottom of the
+screen. If more lines were required, two locations could be employed, allowing
+the top and bottom regions to occupy the entire screen.
 
 Enhancement: Screen Height Adjustment
 -------------------------------------
@@ -537,6 +544,10 @@
 performance benefit would be derived from giving the CPU full access to the
 memory bandwidth.
 
+The region blanking feature mentioned above could be implemented using this
+enhancement instead of employing palette blanking for the affected lines of
+the display.
+
 Enhancement: Memory Filling
 ---------------------------