# Metal diagnostic — read the colors

Two independent diagnostics are built into this ISO. Boot the NVS 295 from it
(Rufus, DD mode) and watch closely.

## A) Boot-stage markers (small squares along the TOP-LEFT)

As the kernel boots it paints four small squares left-to-right. Whatever is the
LAST one you see (frozen, or the last thing before it reboots) tells us how far
it got:

  [GREEN][CYAN][YELLOW][WHITE]
     |     |      |      |
     |     |      |      +-- WHITE : entered the C64 run loop (furthest)
     |     |      +--------- YELLOW: C64 built + display initialized
     |     +---------------- CYAN  : heap memory manager constructed
     +---------------------- GREEN : heap about to initialize (earliest)

If you then see the **BLUE C64 screen**, all four passed — good.

## B) Exception freeze (a small square in the TOP-LEFT CORNER)

If a CPU fault happens, the machine now HALTS (no memory-heavy paint that could
re-crash) and shows a tiny corner square whose color names the fault:

  RED     = General Protection fault
  MAGENTA = Page fault (touched unmapped/reserved memory)  <-- my top suspicion
  YELLOW  = Invalid opcode
  GREEN   = Divide by zero
  DK BLUE = Double fault
  WHITE   = other

## What to tell me — ONE of these:

1. "It still reboots instantly, I see no squares at all" (reboot is very early /
   not a catchable exception — I look at the boot/GRUB path)
2. "It freezes showing [COLOR] square(s)" — tell me which marker colors you saw
   AND any corner fault color. That pinpoints the exact failing stage + fault.
3. "It reaches blue then reboots" (fault is inside the C64 loop specifically)

This turns the reboot into a specific answer instead of a guess.
