Current draw on step C surface?

[Altitude]

ball park figure? using 4x 6581's but i am most concerned with the 5V rail

[Wilba]

Be most concerned with any LED backlit LCD display. That will be the biggest single current draw, I think... You'll also need to calculate the draw of each LED, as it will depend on the type of LED and the current limiting resistor you're using (and to some degree, max current the DOUT can source).

Ballpark figure: 5V at 1A is usually enough. Note that a lot of people have used the C64 PSU with step C control surface.

[Altitude]

I wont be using the c64 psu since i will need +/- 12V. The 7805 in the TO-220 can only go up to 1 amp and i am using a low current LCD so hopefully it will be enough