Method 1.

Connect OSC2 from the PIC with the Crystal, to OSC1 of the PIC's without. Disadvantage: If you are driving more than about 2 or three slave PICs, you will need a simple CMOS or TTL driver/buffer as it will load the Master's oscillator too much. You have to set the Master for HC Oscillator (even at clock rates of 4MHz or under) to provide extra drive on the Oscillator if you have more than one slave PIC. I have many thousands of a design in the field with one master and two slaves without any problems whatsoever using this method.


Method 2.

Connect OSC2 from the PIC1 with the Crystal, to OSC1 of PIC2 without. PIC2's OSC2 connects to PIC3's OSC1. PIC3's OSC2 connects to PIC4's OSC1... ad infinitum... Disadvantage: If one of the PICs failed, all the PICs down the chain from that PIC will cease operating also.


You can use any combination of Method 1 and Method 2 to construct Oscillator arrays as big as you wish.


Method 3.

Use a CMOS HEX Inverter/Driver IC and build a simple conventional Oscillator (as you would do if you were building a standard non-PIC logic design. Fan this out to heaps of PICs on your PCB as each HEX inverter/buffer stage should be able to fan-out to over a dozen PICs.


Method 4.

Use a ready-built 'canned' Oscillator... careful though, some of those TTL ones generate heaps of RFI...