Once you identify each component and assign it a two-letter code, preferably starting with "AA" you are then ready to interconnect the two-port networks.

There are four two-port interconnection schemes; they're named CAS, CAX, PAR, and SER. Each is shown below.

The CAS code is shorthand for cascade, but, its a special type of cascade. It's used to interconnect adjacent two-ports, or, in two different locations in a network. These two networks do not have to be in alphabetical order. A CAS AA DD command, as shown in the panel on the far left below, will create a new two-port named "AA." However, although the original "AA" will be lost, the "DD" will remain safe in memory.

The CAX code is a modified version of CAS. It allows you to cascade several two-ports simultaneously. However, one caveat. they must be in alphabetical order. Example: A CAX AA CC command will create a new two-port named "AA" using "AA," "BB," and "CC." The original "AA" is gone, but "BB" and "CC" remain untouched.

The PAR code stands for parallel. An easy way to visualize this is the addition of shunt feedback from collector to base in an amplifier. Example: If "KK" is a series resistor-inductor feedback network, (an "SRL"), and "LL" is a transistor, the command PAR KK LL will create a new two-port named "KK."

The SER code means series. Use this if you want to add a resistor into the emitter lead of a transistor, or to add inductance into the base lead if you're designing a CB oscillator. Example: If "RR" is a "TWO," (a two-port), and "SS" is a parallel resistor, the command SER RR SS will create a new "RR" as shown in the sketch on the far right.

Here are sketches showing the various interconnections, what you start with at the top of each panel, and what you end with at the bottom.