Not all old T-2, era Mazaks had background editing capability as this was supposedly an option, but I have yet to find one missing the capability so far.
You have to push cycle start from beginning of program when on one of the 'run side' screens as usual. After machine is rolling, you can then go back to program screen and create a new program in usual manner.
Shape check will function normally while machine is busy cutting chips, but you cannot execute toolpath check at this time as the computer cannot 'chew gum and walk at same time' so to speak. If you push 'feed hold' button, machine is no longer 'preoccupied' with making parts and can execute the toolpath check. After checking the toolpath, you can then go back to run screens and hit cycle start again to continue making parts. It works.
Every once in a while*, my machine will not let me edit a previously run program in the background when cutting chips. To get around this hiccup, I simply create a new program with same header information and then copy the entire program into new work number. I then go back and erase the 'old' program after machine stops. This will only work if you have enough memory space available in the control.
* I do not know if this edit lockout is related to the layout screen being altered from default in that program, but I have not spent the time to investigate the phenomenon. I do know that whenever you copy a program, the layout screen goes back to normal default sequence numerical order.
