Assuming that everything MECHANICAL (ie, camshaft, timing chain) is working properly: pull the #1 plug, put your compression gauge tube in the hole WITHOUT connecting the compression gauge (assuming you have a 2 piece compression gauge), put your finger over the hole in the compression gauge tube, turn the engine by hand, using a long rachet and socket until you feel the compression. At this point you have 2 options, slowly turn the engine by hand until pressure stops and you start feeling vacuum, then turn the rachet the other direction a couple times until you have split the difference between compression and vacuum. It's actually a pretty good guess, but if you can see the timing mark you can get it EXACTLY on TDC.
the piston in cylinder #1 at the top on the compression stroke
It is when the number one cylinder has reached top dead center on the compression stroke.
That would be the top of the compression stroke on the number one cylinder.
The location of the ECU is in the engine bay dead center...
The TDC is when the number one cylinder is at the top or top dead center of the compression.
There is no direct connection between compression ratio and pressure. Ratio is a mathematical calculation of the cylinder volume from bottom center to top center. Actual cylinder pressure will depend on the volumetric efficiency of the engine. Factors the affect volumetric efficiency include rpm, intake design, throttle plate size, amount of restriction in the exhaust, size of the valves, shape of piston and combustion chamber.
No, it is in crankshaft degrees, an example: intake centerline of 108* degrees, means the centerline occurs 108 degrees past Top dead center on cylinder 1.
This means the timing is set to fire the spark plugs at 10 degrees before top dead center on the compression stroke.
Look at the distributor and make a mark on the housing where the #1 cylinder connects. Then pull the distributor cap. The mark is so you know where #1 is with the cap off. Next, bring #1 cylinder to top dead center on the compression stroke. The rotor should be pointing at the mark you made. If you need directions on how to get #1 to TDC on the compression stroke - another topic..
In the field of automotive repair, we always refer to top dead center as. The #1 cylinder being at the TOP MOST POSITION during its compression stroke. The 22RE is no exception.
Presumably we are talking 4 stroke? If so, none or the exhaust - it will be at the top of the compression or the exhaust stroke