Update for 03-11-21 17:15

tech/arduino_nano.wiki

@@ -42,7 +42,6 @@ Pins are controller by the atmega's ports. Each port has different port
 registers. Each bit of the 8 bit register controls a single pin. Port D
 controls pins 0 through 7, C controls the analog pins, and B controls 8 through
 13
-
 * PortC
   - Port C data regiser
   - 0x28
@@ -135,7 +134,7 @@ controlling Timer/Counter 1, along with Timer Counter 1 Control Register B
 compare output mode for channel A and B respectivly. These are controlled with
 2 bit combinations as shown below. 
 
-NOTE These settings only apply to normal mode
+NOTE These settings only apply to normal mode, and are on TTCR1A
 
 | Bits | Description |
 ----------------------
@@ -191,6 +190,8 @@ set when The input capture set by WGM to be used as the TOP value. Bits 2-0 are
 set when TCNT1 matches the value in OCR1B, OCR1A, when when TCNT1 overflows,
 respectivly.
 
+==== Prescaler ====
+
 To make the clock useful, the following will be an example of how to use Timer
 1 to delay a certain amount of time. You will need the following information
 
@@ -203,3 +204,16 @@ the desired freqency. Be sure that the value is smaller than the max timer
 value. If it is to large, choose a larger prescaler. Then place this in the
 OCR** Register and enable the desired interrupt.
 
+To assist in finding the correct value, below are the values of the clock speed
+(16Mhz) over the prescalers.
+
+NOTE to help with calculations, 0xFFFF is 65536 and 0xFF is 256
+
+| prescaler | value |
+---------------------
+| 8    | 2000000 |
+| 64   | 250000  |
+| 256  | 62500   |
+| 1024 | 15625   |
+
+