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document register_screen and readline in the readme

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1 parent 74fd51d commit 7c1e226898843666a1481c00f70e90b0a9f41960 @fhars committed
Showing with 21 additions and 3 deletions.
  1. +21 −3 readme.md
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24 readme.md
@@ -191,9 +191,11 @@ displayed on the screen below the status lines. That process is also
said to "have focus". The user can cycle between the processes using
tab (and, in some emulators, Pg_Up and Pg_Dn).
-The current implementation is quite primitive: everytime the user
-switches to the next process, the screen is cleared and output starts
-on the top of the screen.
+By default, everytime the user switches to the next process, the
+screen is cleared and output starts on the top of the
+screen. Alternatively, a process may register a 320 word buffer to use
+a a backing store that is uses for the video content while the process
+is not running.
Key presses will be deliverd to the process that has the focus. dcos16
stores one key per process, additional keys pressed before the
@@ -209,6 +211,13 @@ containing the characters in their lower seven bits.
The output functions have no effect if the process does not have
focus.
+register_screen
+---------------
+
+Call this method if the process should have a persistent video output
+even if it loses focus. The process must provide a 320 word buffer to
+store the video content.
+
getch
-----
@@ -222,6 +231,15 @@ readch
either the last key pressed, suspending the process until a key has
been presse if none is available.
+readline
+--------
+
+```readline``` reads a line of up to 32 characters (including the
+terminating zero) into the buffer pointed to by A, blocking until
+characters are available. B contains the length of the buffer. For
+```readline``` to be useful, the process must have reserved screen
+memory, as the effects are undefined otherwise.
+
println
-------

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