Editing Sad Mac Decoder (section)

== What the codes mean ==

A Sad Mac code is a dump of the CPU's D6 and D7 registers at the moment the diagnostic routine gave up. The lower word of D7 identifies which test was running (or which exception fired), and D6 holds the specifics — a bitmask of failing data lines, an address-line XOR, the stack pointer, etc. If an unexpected 68000-family exception interrupted a test, the exception number is logically ORed into the test number, so a code like {{code|00000304}} means "''illegal instruction'' (03) fired during ''RAM Bank A test'' (04)".

For the full breakdown, including the [[Sad Mac Error Codes#Test Manager flags (upper word of D7)|Test Manager flag bits]], every per-model test table, and the [[Sad Mac Error Codes#Macintosh Portable Diagnostic Codes|Macintosh Portable]]'s separate code set, see the [[Sad Mac Error Codes|main reference page]].