Sad Mac Decoder: Difference between revisions
Create standalone Sad Mac Decoder page (host for the saddecoder gadget) |
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== What the codes mean == | == 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 | 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]]. | 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]]. | ||
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* [[Sad Mac Error Codes]] — full reference | * [[Sad Mac Error Codes]] — full reference | ||
* [[Macintosh SE/30 Troubleshooting]] | * [[Macintosh SE/30 Troubleshooting]] | ||
[[Category:Apple Troubleshooting Guides]] | [[Category:Apple Troubleshooting Guides]] | ||
Revision as of 20:46, 20 May 2026
The Sad Mac Decoder is an interactive tool for decoding Sad Mac Error Codes across every 68k Macintosh model. Enter the hex codes shown on a non-booting Mac, pick the machine model, and the decoder will tell you which test failed, identify the specific failing RAM chip (where applicable), and play back the corresponding Chime of Death.
For the underlying reference tables, worked examples, and background on how the codes are generated, see the full article at Sad Mac Error Codes.
Decoder
How to use
- Pick your machine from the Machine dropdown. The format of the codes (short vs. expanded two-line) is set automatically.
- Enter the hex code shown below the Sad Mac icon. Compact Macs (128K, 512K, Plus) display a single six-digit code; everything from the SE onwards uses two lines of eight hex digits.
- Click Decode. For RAM-fault classes you'll also see a board diagram with the failing chip(s) highlighted in red.
- Click ▶ Play this machine's Chime of Death to hear a synthesised approximation of the audio that machine produces alongside the Sad Mac. Compact Macs (128K through Plus) are silent on failure and will show a notice instead.
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 00000304 means "illegal instruction (03) fired during RAM Bank A test (04)".
For the full breakdown, including the Test Manager flag bits, every per-model test table, and the Macintosh Portable's separate code set, see the main reference page.
See also
- Sad Mac Error Codes — full reference
- Macintosh SE/30 Troubleshooting