The dispatch status is 0x100 (printed as '22' in the message). A driver-side
transparent low-RAM write log (VT1200_LOWLOG) shows the slot at bit 0x16F0 is
written by the store at 3FDF9090 from a13(0x10), which L3FA7C050 sets to the
literal 0x100 when the memory test L3F2018B0 returns non-zero. L3F2018B0 is the
level-1 video-memory test (base bit 0x04000000, count 0x20000). Its failing
checks: the 16-bit walking-bit read-back at 0x04000000 (baseline, unmapped) and,
with video RAM mapped, the REFCNT (0xC00001F0) 'must change' check.
