Feature Request: breakpoint on VDP address

[jedimatt42]

last week I was debugging code that erroneously wrote to the screen when in 80x30 mode. js99er is the only emulator that handles that mode correctly.

I had no idea what code was writing that character.. it was part of some level 2 io code... just shouldn't have touched hte screen at all.. but I could identify visually approximately where the write was in vdp, then pinpoint the address I wanted to break on, but couldn't figure out if there was a way to set a vdp breakpoint.

So I ran in classic99, which does let me break point, to find that the io routine was using a vdpchar routine out of libti99 that we hijacked to automatically fill in the color attribute when writing a byte... anyway, vdpchar in libti99 with extended attributes on is no longer a generalized VSBW routine, so it shouldn't be used as such in the dsrlnk implementation... ( ok that was still a long story )

A breakpoint on VDP write would have allowed discovering and resolving this with one emulator instead of 2.