diff --git a/docs/IMPLEMNT.md b/docs/IMPLEMNT.md
index 6e55d11a..0d8b74be 100644
--- a/docs/IMPLEMNT.md
+++ b/docs/IMPLEMNT.md
@@ -1,7 +1,8 @@
 PDCurses Implementor's Guide
 ============================
 
-- Version 1.6 - 2019/09/?? - added PDC_doupdate(); removed
+- Version 1.6 - 2019/09/?? - added PDC_doupdate(); removed SP allocation
+                             from PDC_scr_open(); removed
                              PDC_init_pair(), PDC_pair_content()
 - Version 1.5 - 2019/09/06 - PDC_has_mouse(), removed PDC_get_input_fd()
 - Version 1.4 - 2018/12/31 - PDCurses.md -> USERS.md, MANUAL.md; new dir
@@ -254,15 +255,13 @@ The platform-specific part of initscr(). It's actually called from
 Xinitscr(); the arguments, if present, correspond to those used with
 main(), and may be used to set the title of the terminal window, or for
 other, platform-specific purposes. (The arguments are currently used
-only in X11.) PDC_scr_open() must allocate memory for SP, and must
-initialize acs_map[] (unless it's preset) and several members of SP,
-including lines, cols, mouse_wait, orig_attr (and if orig_attr is TRUE,
-orig_fore and orig_back), mono, _restore and _preserve. (Although SP is
-used the same way in all ports, it's allocated here in order to allow
-the X11 port to map it to a block of shared memory.) If using an
-existing terminal, and the environment variable PDC_RESTORE_SCREEN is
-set, this function may also store the existing screen image for later
-restoration by PDC_scr_close().
+only in X11.) PDC_scr_open() must initialize acs_map[] (unless it's
+preset) and several members of SP, including lines, cols, mouse_wait,
+orig_attr (and if orig_attr is TRUE, orig_fore and orig_back), mono,
+_restore and _preserve. If using an existing terminal, and the
+environment variable PDC_RESTORE_SCREEN is set, this function may also
+store the existing screen image for later restoration by
+PDC_scr_close().
 
 
 pdcsetsc.c:
diff --git a/dos/pdcscrn.c b/dos/pdcscrn.c
index 0e790a0a..79a57060 100644
--- a/dos/pdcscrn.c
+++ b/dos/pdcscrn.c
@@ -496,11 +496,6 @@ int PDC_scr_open(int argc, char **argv)
 
     PDC_LOG(("PDC_scr_open() - called\n"));
 
-    SP = calloc(1, sizeof(SCREEN));
-
-    if (!SP)
-        return ERR;
-
     for (i = 0; i < 16; i++)
         pdc_curstoreal[realtocurs[i]] = i;
 
diff --git a/os2/pdcscrn.c b/os2/pdcscrn.c
index 497bc38c..2fecb4a1 100644
--- a/os2/pdcscrn.c
+++ b/os2/pdcscrn.c
@@ -93,11 +93,6 @@ int PDC_scr_open(int argc, char **argv)
 
     PDC_LOG(("PDC_scr_open() - called\n"));
 
-    SP = calloc(1, sizeof(SCREEN));
-
-    if (!SP)
-        return ERR;
-
     for (i = 0; i < 16; i++)
         pdc_curstoreal[realtocurs[i]] = i;
 
diff --git a/pdcurses/initscr.c b/pdcurses/initscr.c
index 2fc135a1..e433bb55 100644
--- a/pdcurses/initscr.c
+++ b/pdcurses/initscr.c
@@ -128,6 +128,10 @@ WINDOW *Xinitscr(int argc, char *argv[])
     if (SP && SP->alive)
         return NULL;
 
+    SP = calloc(1, sizeof(SCREEN));
+    if (!SP)
+        return NULL;
+
     if (PDC_scr_open(argc, argv) == ERR)
     {
         fprintf(stderr, "initscr(): Unable to create SP\n");
diff --git a/sdl1/pdcscrn.c b/sdl1/pdcscrn.c
index 244761a8..31358cd1 100644
--- a/sdl1/pdcscrn.c
+++ b/sdl1/pdcscrn.c
@@ -128,11 +128,6 @@ int PDC_scr_open(int argc, char **argv)
 {
     PDC_LOG(("PDC_scr_open() - called\n"));
 
-    SP = calloc(1, sizeof(SCREEN));
-
-    if (!SP)
-        return ERR;
-
     pdc_own_screen = !pdc_screen;
 
     if (pdc_own_screen)
diff --git a/sdl2/pdcscrn.c b/sdl2/pdcscrn.c
index bafb4521..be52d32b 100644
--- a/sdl2/pdcscrn.c
+++ b/sdl2/pdcscrn.c
@@ -138,11 +138,6 @@ int PDC_scr_open(int argc, char **argv)
 {
     PDC_LOG(("PDC_scr_open() - called\n"));
 
-    SP = calloc(1, sizeof(SCREEN));
-
-    if (!SP)
-        return ERR;
-
     pdc_own_window = !pdc_window;
 
     if (pdc_own_window)
diff --git a/wincon/pdcscrn.c b/wincon/pdcscrn.c
index e9fbb4e4..0e45a67f 100644
--- a/wincon/pdcscrn.c
+++ b/wincon/pdcscrn.c
@@ -385,11 +385,6 @@ int PDC_scr_open(int argc, char **argv)
 
     PDC_LOG(("PDC_scr_open() - called\n"));
 
-    SP = calloc(1, sizeof(SCREEN));
-
-    if (!SP)
-        return ERR;
-
     for (i = 0; i < 16; i++)
     {
         pdc_curstoreal[realtocurs[i]] = i;
diff --git a/x11/pdcscrn.c b/x11/pdcscrn.c
index db54407e..65d1af1e 100644
--- a/x11/pdcscrn.c
+++ b/x11/pdcscrn.c
@@ -561,8 +561,6 @@ int PDC_scr_open(int argc, char **argv)
     if (!strcmp(pdc_app_data.textCursor, "vertical"))
         pdc_vertical_cursor = TRUE;
 
-    SP = calloc(1, sizeof(SCREEN));
-
     SP->lines = LINES;
     SP->cols = COLS;