adding Teensy

GPIO/Arduino/ring.ino

+//
+// ring.ino
+//
+// ring oscillator test
+//
+// Neil Gershenfeld 8/12/21
+//
+// This work may be reproduced, modified, distributed,
+// performed, and displayed for any purpose, but must
+// acknowledge this project. Copyright is retained and
+// must be preserved. The work is provided as is; no
+// warranty is provided, and users accept all liability.
+//
+
+void setup() {
+   pinMode(0,OUTPUT);
+   }
+
+void loop() {
+   while (1) {
+      /*
+      if (digitalRead(1))
+         digitalWrite(0,LOW);
+      else
+         digitalWrite(0,HIGH);
+      */
+      if (digitalReadFast(1))
+         digitalWriteFast(0,LOW);
+      else
+         digitalWriteFast(0,HIGH);
+      }
+   }