The 6502 machines were a bit more forgiving with hardware issues.
For example - On the Apple II/IIIs, if part of RAM fails, the system would only accept what RAM is left and the machine would work with the smaller RAM amount, depending on where it would fail. It usually was with 16K or 8K blocks. Thus givien an Apple II with 64K RAM:
If memory fails on the top 64K, it would default to a 48K setting.
If memory fails around 48K area, it would default to a 32K setting.
If memory fails around 32K area, it would default to a 16K setting.
If memory fails around 16K area, it would default to a 8K setting.
Now, if memory fails within this 8K area, it could default into a 4K setting or it would give a screen of jumbled characters. The most important part of memory for a 6502 machine is the Zero Page of RAM which is the first 256 Bytes of RAM. If RAM fails in this area, then the Apple (and other 6502 machines) would not be able to boot because this is the area that the CPU uses to store its registers and processor stack information. Anything above Zero Page is for the User to program, mostly taken up by the OS to the first 1K.
Other things that could fail - mostly I/O, would simply not work. If your Disk Drive Card fails, you would not be able to use your disk drives, you would be able to use the rest of the machine. Same with your other cards. Only problem here is if your Octal Buffers Chips which controls the slots - if they fail, then none of your slots would work. But that is an easy fix once you find which chips to replace.
Sometimes the Keyboard Processor Chip fails so you either get dead rows of keys or your keyboard would not work at all. And if your CPU fails, you get a screen of jumbled characters or a blank screen.
All of these issues are simple fixes once you diagnosed the problem. But there are no "Sad Mac" Code for the Apple or most 6502 machines I know of, you just need to know the symptoms effecting the machine and fix as needed.
For example - On the Apple II/IIIs, if part of RAM fails, the system would only accept what RAM is left and the machine would work with the smaller RAM amount, depending on where it would fail. It usually was with 16K or 8K blocks. Thus givien an Apple II with 64K RAM:
If memory fails on the top 64K, it would default to a 48K setting.
If memory fails around 48K area, it would default to a 32K setting.
If memory fails around 32K area, it would default to a 16K setting.
If memory fails around 16K area, it would default to a 8K setting.
Now, if memory fails within this 8K area, it could default into a 4K setting or it would give a screen of jumbled characters. The most important part of memory for a 6502 machine is the Zero Page of RAM which is the first 256 Bytes of RAM. If RAM fails in this area, then the Apple (and other 6502 machines) would not be able to boot because this is the area that the CPU uses to store its registers and processor stack information. Anything above Zero Page is for the User to program, mostly taken up by the OS to the first 1K.
Other things that could fail - mostly I/O, would simply not work. If your Disk Drive Card fails, you would not be able to use your disk drives, you would be able to use the rest of the machine. Same with your other cards. Only problem here is if your Octal Buffers Chips which controls the slots - if they fail, then none of your slots would work. But that is an easy fix once you find which chips to replace.
Sometimes the Keyboard Processor Chip fails so you either get dead rows of keys or your keyboard would not work at all. And if your CPU fails, you get a screen of jumbled characters or a blank screen.
All of these issues are simple fixes once you diagnosed the problem. But there are no "Sad Mac" Code for the Apple or most 6502 machines I know of, you just need to know the symptoms effecting the machine and fix as needed.