I have seen those strange artifacts on my SE/30 screen! I have never had or used a non-stock ROM in my SE/30.
Before I replaced the capacitors on my motherboard, my SE/30 started displaying that pattern instead of starting up (no bong either) and would usually eventually bong and boot. After the replacement of the caps, it doesn't happen very often, but maybe twice a year it'll no-bong and show that.
I just always assumed that that pattern was the values the VRAM took by default when powered-up but not initialized. I was guessing that something was a little flaky in the power-on-reset and the CPU wasn't being told to bootstrap the ROM. Without any processor, the rest of the Mac will just go on its merry default way, so I assumed that was the uninitialized VRAM.
Do we even know where the VRAM lives in an SE/30? Is it stored in system memory? The jail or checkerboard pattern from misinstalled RAM seems to make me think so...
Before I replaced the capacitors on my motherboard, my SE/30 started displaying that pattern instead of starting up (no bong either) and would usually eventually bong and boot. After the replacement of the caps, it doesn't happen very often, but maybe twice a year it'll no-bong and show that.
I just always assumed that that pattern was the values the VRAM took by default when powered-up but not initialized. I was guessing that something was a little flaky in the power-on-reset and the CPU wasn't being told to bootstrap the ROM. Without any processor, the rest of the Mac will just go on its merry default way, so I assumed that was the uninitialized VRAM.
Do we even know where the VRAM lives in an SE/30? Is it stored in system memory? The jail or checkerboard pattern from misinstalled RAM seems to make me think so...