With Decimal Programming, each item that is controlled in that CV has a value. It's as simple as adding up the values for the features you want turned on and programming that value into the CV.

CVs are made up of eight bits, numbered from zero through seven (0-7). Each of these bits has a value, starting with bit zero (0) having a value of one (1). Each subsequent bits value is double that of the preceding bit. Therefore, bit 1 has a value of 2, bit two has a value of 4, bit 3 has a value of 8, and so on.

Following is a list showing bits and values:

If you program a zero into the CV, all bits are turned off. If you add up all the values, you'll find that there's a total value of 255. Programming 255 into the CV turns all bits on. Let's get specific for CV29.

If you want the base direction to be forward, you leave bit 0 off.
If you want to run in the 28 or 128 speed-step mode, you turn bit 1 on.
If you don't want Automatic Analog Conversion, you leave bit 2 off.
If you want to use the built-in speed curve, leave bit 4 off.
If you want to use four-digit addressing, bit 5 must be turned on.

Since all other bits must be left off, the only two bits to turn on are #s 1 and 5. The value for bit 1 is 2 and the value for bit 5 is 32. So you add 2 and 32 together to get 34 and program that into CV29.

Simple enough. Yes, but if your system can program only in Hexadecimal, such as with a DT100 or DT300 throttle, that decimal value has to be converted to Hexadecimal. For information about that, refer to Hex/Decimal Conversions.

Also, some values can be higher (especially with SoundTraxx sound decoders), to a point of not being able to calculate it in your head. If your system is capable of Hexadecimal programming, you may want to check out Hexadecimal Calculations. However, if you're stuck with Decimal, you can always get out a pencil and paper (or pocket calculator).