Sad Mac Decoder: Difference between revisions
Verification drive: labelled as {{Original research}}; spelled out the FFFFEETT layout so it matches the Sad Mac Error Codes page and the gadget's own parsing; added 512Ke to the short-format model list to match the gadget; noted that the chimes are synthesised rather than sampled |
Add the Sad Mac illustration to the decoder page |
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[[File:Sad Mac.png|thumb|right|A Sad Mac with its error code. The decoder below turns those digits into a named test and, where the code allows, a chip position.]] | |||
{{Original research|The decoder's model list, test tables, exception table and chime synthesis were built by this wiki's contributors from the codes the machines themselves produce.}} | {{Original research|The decoder's model list, test tables, exception table and chime synthesis were built by this wiki's contributors from the codes the machines themselves produce.}} | ||
Latest revision as of 23:30, 23 September 2026
Original research by RetroTechCollection.The decoder's model list, test tables, exception table and chime synthesis were built by this wiki's contributors from the codes the machines themselves produce. This section records work carried out and measurements taken by this wiki's contributors rather than information drawn from a published source. It is offered as first-hand documentation — no external citation exists because the work is the source. Corrections and independent confirmation are welcome.
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
[edit | edit source]How to use
[edit | edit source]- 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, 512Ke and 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 the audio that machine produces alongside the Sad Mac. Compact Macs (128K through Plus) are silent on failure and will show a notice instead.
- The chimes are synthesised in the browser for A/B comparison. They are close enough to identify a machine family by ear; they are not recordings of the original samples.
What the codes mean
[edit | edit source]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, and so on. If an unexpected 68000-family exception interrupted a test, the exception number is ORed in above the test number, so line 1 reads FFFFEETT: a code like 00000304 means "illegal instruction (03) fired during the 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
[edit | edit source]- Sad Mac Error Codes — full reference
- Macintosh SE/30 Troubleshooting
- Macintosh Old World ROM — what the boot ROM is doing when it draws the Sad Mac