Editing Sad Mac Error Codes (section)

=== Test Manager flags (upper word of D7) ===

On expanded-format machines the upper four hex digits of line 1 are not random — they are the live state of the Test Manager. Each bit has a meaning:

{| class="wikitable"
|+ Test Manager flag bits (D7 bits 16–31)
! Bit !! Flag !! Meaning when set
|-
| 16 || Message queued || A diagnostic message is pending in the serial output queue
|-
| 17 || SCC INITed || The SCC serial controller has been initialised
|-
| 18 || No-sleep || Auto-sleep is inhibited (Portable / PowerBook)
|-
| 19 || Star received || A {{code|*}} command character has been received over the serial diagnostic port — Test Manager is active
|-
| 20 || ASCII input || Test Manager expects ASCII command input (clear = hexadecimal)
|-
| 21 || Echo || Echo received characters back over the serial port
|-
| 22 || Timer || Timer-based testing enabled
|-
| 23 || Newline || Emit CR/LF after every Test Manager response
|-
| 24 || Unexpected exception || An unexpected exception was caught — exception code is ORed into the test number
|-
| 25 || Programmer's key || The Programmer's Switch (NMI button) was pressed
|-
| 26 || VIA Test || A VIA test is currently asserting itself on the bus
|-
| 27 || Bus errors OK || Bus errors are expected (used during chip-probe tests)
|-
| 28 || Stop on error || Halt on the first error rather than continuing
|-
| 29 || Loop on error || Loop the failing test indefinitely (for scope/logic-analyser work)
|-
| 30 || Store in PRAM || Persist test results to PRAM
|-
| 31 || Boot after test || Continue booting after diagnostics complete
|}

In practice, when looking at a Sad Mac code in the wild, the upper word usually reads '''0000''' (no flags set, normal boot), '''0001''' (a serial message had been queued before the failure), or a value with bit 24 (0x0100) and/or bit 25 (0x0200) set if the failure was exception-driven or operator-induced.