--- a/io.c	Sun Jul 08 16:15:34 2018 +0900
+++ b/io.c	Mon Jul 09 00:40:05 2018 +0900
@@ -49,7 +49,7 @@
  *   IOPAGE ~ IOPAGE+0x7f
  *       for OS9 level2
  *       IOPAGE 0xff80 means ioport beging 0xff80 but IOPAGE itself starts 0xff00
- *       0xff00-0xff7f, 0xffe0-0xffff can be used as ROM in fixed area
+ *       0xfe00-0xff7f, 0xffe0-0xffff can be used as ROM in fixed area
  *
  *   IOPAGE + 0x00   ACIA  control
  *   IOPAGE + 0x01   ACIA  data
@@ -187,13 +187,13 @@
 
 int do_input(int a) {
         static int c, f = EOF;
-        if (a == 0+(IOPAGE&0xff)) {
+        if (a == 0+(IOPAGE&0x1ff)) {
                 if (f == EOF)
                         f = char_input();
                 if (f != EOF)
                         c = f;
                 return 2 + (f != EOF);
-        } else if (a == 1+(IOPAGE&0xff)) { /*data port*/
+        } else if (a == 1+(IOPAGE&0x1ff)) { /*data port*/
                 if (f == EOF)
                         f = char_input();
                 if (f != EOF) {
@@ -202,12 +202,12 @@
                 }
                 return c;
         }
-        return mem[(IOPAGE&0xff00) + a];
+        return mem[(IOPAGE&0xfe00) + a];
 }
 
 void do_output(int a, int c) {
         int i, sum;
-        if (a == 1+(IOPAGE&0xff)) { /* ACIA data port,ignore address */
+        if (a == 1+(IOPAGE&0x1ff)) { /* ACIA data port,ignore address */
                 if (!xmstat) {
                         if (logfile && c != 127 && (c >= ' ' || c == '\n'))
                                 putc(c, logfile);
@@ -253,11 +253,11 @@
                                 xidx = 0;
                         }
                 }
-        } else if (a >= 0x40+(IOPAGE&0xff)) { /* disk */
+        } else if (a >= 0x40+(IOPAGE&0x1ff)) { /* disk */
              do_disk(a,c);
-        } else if (a >= 0x30+(IOPAGE&0xff)) { /* timer */
+        } else if (a >= 0x30+(IOPAGE&0x1ff)) { /* timer */
              do_timer(a,c);
-        } else if (a >= 0x10+(IOPAGE&0xff)) { /* mmu */
+        } else if (a >= 0x10+(IOPAGE&0x1ff)) { /* mmu */
              do_mmu(a,c);
         }
 }
@@ -275,17 +275,17 @@
 
 void do_timer(int a, int c) {
    struct itimerval timercontrol;
-   if (a==0x30+(IOPAGE&0xff) && c==0x8f) {
+   if (a==0x30+(IOPAGE&0x1ff) && c==0x8f) {
         timercontrol.it_interval.tv_sec = 0;
         timercontrol.it_interval.tv_usec = 20000;
         timercontrol.it_value.tv_sec = 0;
         timercontrol.it_value.tv_usec = 20000;
         setitimer(ITIMER_REAL, &timercontrol, NULL);
-   } else if (a==0x30+(IOPAGE&0xff) && c==0x80) {
+   } else if (a==0x30+(IOPAGE&0x1ff) && c==0x80) {
         timercontrol.it_interval.tv_sec = 0;
         timercontrol.it_interval.tv_usec = 0;
         setitimer(ITIMER_REAL, &timercontrol, NULL);
-   } else if (a==0x30+(IOPAGE&0xff) && c==0x04) {
+   } else if (a==0x30+(IOPAGE&0x1ff) && c==0x04) {
       time_t tm = time(0);
       struct tm *t = localtime(&tm);
       mem[IOPAGE+0x31] = t->tm_year;
@@ -295,13 +295,13 @@
       mem[IOPAGE+0x35] = t->tm_min;
       mem[IOPAGE+0x36] = t->tm_sec;
    } else {
-      mem[(IOPAGE&0xff00)+a]=c;
+      mem[(IOPAGE&0xfe00)+a]=c;
    }
 }
 
 void do_disk(int a, int c) {
-   if (a!=0x40+(IOPAGE&0xff)) {
-      mem[(IOPAGE&0xff00)+a]=c;
+   if (a!=0x40+(IOPAGE&0x1ff)) {
+      mem[(IOPAGE&0xfe00)+a]=c;
       return;
    }
    int drv = mem[IOPAGE+0x41];
@@ -325,14 +325,14 @@
 {
 #ifdef USE_MMU
 
-   if (a==0x11+(IOPAGE&0xff)) {
+   if (a==0x11+(IOPAGE&0x1ff)) {
        if (c&1) {
            mmu = phymem+memsize-0x10000+0xffa8;
        } else {
            mmu = phymem+memsize-0x10000+0xffa0;
        }
    }
-   mem[(IOPAGE&0xff00)+a] = c;   // other register such as 0xffa0-0xffaf
+   mem[(IOPAGE&0xfe00)+a] = c;   // other register such as 0xffa0-0xffaf
 #endif 
 }