help with isp pcb

I am designing a board for programming chips with a usbtinyisp, I am going to use a 28 pin zif socket. I am breaking to the socket out 4 isp headers, one each for 28 dip, 20 dip, 14 dip, and 8 dip chips. The question I had was just for programming the chips can I leave out the decoupling caps you normally use? I know for the attiny84 I can leave them out and it works fine. Here are the schematic and board layout, sorry it's a rat's nest. I'm just learning kicad now and this is my first board. I used an autorouter too :frowning: once I get better at it I'll do them by hand.


It's never a good idea to leave out the main decoupling capacitor between Vcc and gnd, although you might get away with it, especially if you mount a decoupling capacitor between the Vcc and gnd pins of the ICSP socket that you plug onto the pins.

Bear in mind that if you want to reprogram a chip that has already been programmed to run with a crystal or resonator, you also need to connect a crystal + caps, resonator, or external clock source to the chip in order to program it.

It might just be easier then to have one icsp header to multiple sockets. If I can get it to work somehow this way then it will save a lot of space on the board. For the clock source I may just add a 16 and 20 Mhz resonator with a switch or something. Thanks for the input. Has anyone else made anything similar that might be able to help with the design?