diff --git a/README.md b/README.md
index d310ca9..f91c2af 100644
--- a/README.md
+++ b/README.md
@@ -265,6 +265,10 @@ directory, type
 	cd apl
 	sudo install_apl
 
+You should see the following line displayed:
+
+        /usr/share/fonts/truetype/apl385/Apl385.ttf: APL385 Unicode:style=Regular
+
 While still being in the apl directory, you can test the APL character set using
 
 	../tek4010 -APL -noexit ./apltest
diff --git a/apl/apltest b/apl/apltest
index bf121ae..847c41a 100755
Binary files a/apl/apltest and b/apl/apltest differ
diff --git a/apl/apltest.c b/apl/apltest.c
index c11efab..0049a30 100644
--- a/apl/apltest.c
+++ b/apl/apltest.c
@@ -26,7 +26,7 @@ int main (int argc, char *argv[])
 		}
 		printf("%c", ch);
 	}
-        printf("\noverstrike test");
+        printf("\n\noverstrike test");
         putchar(62); putchar(32);
         putchar(79); putchar(8); putchar(63); putchar(32);
         putchar(76); putchar(8); putchar(43);
diff --git a/apl/install_apl b/apl/install_apl
index f0b7c1b..aa15bb2 100755
--- a/apl/install_apl
+++ b/apl/install_apl
@@ -3,4 +3,5 @@
 mkdir /usr/share/fonts/truetype/apl385
 cp Apl385.ttf /usr/share/fonts/truetype/apl385
 
-fc-cache /usr/share/fonts
\ No newline at end of file
+fc-cache /usr/share/fonts
+fc-list 'APL385 Unicode'
\ No newline at end of file
diff --git a/main.c b/main.c
index 0ca57f3..8877d92 100644
--- a/main.c
+++ b/main.c
@@ -181,12 +181,12 @@ static void on_key_press(GtkWidget *widget, GdkEventKey *event, gpointer user_da
                 }
                 else if (argAPL && (event->keyval == 0x006E)) { // "<ctrl>n" switch to alternative character set
                         aplMode = 1;
-                        printf("Setting APL mode to 1 from keyboard\n");
+                        // printf("Setting APL mode to 1 from keyboard\n");
                         return;
                 }
                 else if (argAPL && (event->keyval == 0x006F)) { // "<ctrl>o" switch to normalcharacter set
                         aplMode = 0;
-                        printf("Setting APL mode to 0 from keyboard\n");
+                        // printf("Setting APL mode to 0 from keyboard\n");
                         return;
                 }                
                 else
@@ -207,7 +207,7 @@ static void on_key_press(GtkWidget *widget, GdkEventKey *event, gpointer user_da
         }
                 
         else if (putKeys) {
-                if (aplMode) printf("sending character %d to host\n", ch);
+                // if (aplMode) printf("sending character %d to host\n", ch);
                 putc(ch,putKeys);      // pipe key to child process, if stream open
         }
 }
diff --git a/tek4010 b/tek4010
index 40f9249..22e82fe 100755
Binary files a/tek4010 and b/tek4010 differ
diff --git a/tek4010.c b/tek4010.c
index 7b4c7a5..750d69a 100755
--- a/tek4010.c
+++ b/tek4010.c
@@ -205,7 +205,7 @@ void tek4010_escapeCodeHandler(cairo_t *cr, cairo_t *cr2, int ch)
                 case 14: // SO  activate alternative char set
                         if (argAPL) {            // switch only of argAPL is set
                                 aplMode = 1;
-                                printf("Setting APL mode to 1 from computer\n");
+                                // printf("Setting APL mode to 1 from computer\n");
                         }
                         mode = 0;
                         todo = 0;
@@ -214,7 +214,7 @@ void tek4010_escapeCodeHandler(cairo_t *cr, cairo_t *cr2, int ch)
                         aplMode = 0;
                         mode = 0;
                         todo = 0;
-                        printf("Setting APL mode to 0 from computer\n");
+                        // printf("Setting APL mode to 0 from computer\n");
                         break;
                 
                 case 23: system("scrot --focussed"); mode= 0; break;
@@ -358,7 +358,7 @@ void tek4010_draw(cairo_t *cr, cairo_t *cr2, int first)
                         if (mode != 60) return;         // no char available, need to allow for updates
                 }
                 
-                if (aplMode) printf("Receiving character %d from host\n", ch);
+                // if (aplMode) printf("Receiving character %d from host\n", ch);
                 
                 if (DEBUG) {
                         printf("mode=%d, ch code %02X",mode,ch);
diff --git a/tube.c b/tube.c
index ef0440c..5afb8ff 100755
--- a/tube.c
+++ b/tube.c
@@ -177,13 +177,41 @@ int tube_getInputChar()
                 return -1;
 }
 
+void checkFont(char *fontName)
+// check whether font has been installed
+{
+#define MAXL 255
+        FILE *f;
+        int i, ch;
+        char line[MAXL];
+        sprintf(line,"fc-list \'%s\'", fontName); // prepare system call
+        f = popen(line, "r");
+        if (f != NULL) {
+                i = 0;
+                line[0] = 0;
+                while (((ch=fgetc(f))!=EOF) && (i<MAXL-1)) {
+                        line[i++] = ch;
+                }
+                line[i-1]=0;
+                // printf("%s\n",line);
+                if (strstr(line, fontName) > 0) {
+                        pclose(f);
+                        return;
+                }
+       }
+       pclose(f);
+       printf("Error: APL font \'%s\' not installed. This font is required for the APL mode.\n", fontName);
+       printf("See github.com/rricharz/tek4010 paragraph \'APL mode\'\n");
+       exit(1);
+}
+
 void tube_init(int argc, char* argv[])
 // put any code here to initialize the tek4010
 {
         char *argv2[20];
         size_t bufsize = 127;
         int firstArg = 1;
-        printf("tek4010 version 1.3.2\n");
+        printf("tek4010 version 1.3.3\n");
         windowName = "Tektronix 4010/4014 emulator";
         if ((argc<2) || (argc>19)) {
                 printf("Error:number of arguments\n");
@@ -220,6 +248,7 @@ void tube_init(int argc, char* argv[])
                 else if (strcmp(argv[firstArg],"-APL") == 0) {
                         argAPL = 1;
                         windowName = "Tektronix 4013/4015 emulator (APL)";
+                        checkFont(APL_FONT);
                 }
                 else if (strcmp(argv[firstArg],"-ARDS") == 0) {
                         argARDS = 1;
diff --git a/tube.h b/tube.h
index 974e53b..cd72615 100644
--- a/tube.h
+++ b/tube.h
@@ -2,7 +2,7 @@
 
 // fonts
 #define STANDARD_FONT "Monospace"
-#define APL_FONT "APL385  Unicode"
+#define APL_FONT "APL385 Unicode"
 
 enum LineType {SOLID,DOTTED,DOTDASH,SHORTDASH,LONGDASH};
 extern enum LineType ltype;
diff --git a/versions.txt b/versions.txt
index 754aa58..02f32c2 100644
--- a/versions.txt
+++ b/versions.txt
@@ -1,3 +1,8 @@
+Version 1.3.3 May 12, 2019
+=========================
+New features
+- APL mode with APL character set added
+
 Version 1.3.1 May 4, 2019
 =========================
 Bug fixes