Replacing a 68030 in a Mac Classic 2
- Thread starter Redsward
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- 68030 cpu mac classic 2
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The 68k chips are made by Motorola and were in many other machines other than Mac so you are in luck! You’ll want to make sure it’s the correct speed. This one on eBay should work for you.
if eBay isn’t you’d thing just search for “Motorola 68030FE16B”. I’m not sure what the FE or B stands for but 16 is the speed, 16 mhz.
also if the legs were corroded make sure to check the traces aren’t also corroded.
if eBay isn’t you’d thing just search for “Motorola 68030FE16B”. I’m not sure what the FE or B stands for but 16 is the speed, 16 mhz.
also if the legs were corroded make sure to check the traces aren’t also corroded.
Thank-you I thought this might be the case , but doesn't hurt to consult the oracles ! Attached the dead one - I have got the caps off just in time only a couple of trace repairs , though I haven't seen under this one as yet ....
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Some eBay listings sell fake 68k CPUs. See this thread that discusses spotting fake 68k CPUs.
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And this is an excellent guide from the English Amiga Board identifying the abbreviations on the 68k model numbers.
MC - Fully Certified
XC - Engineering Sample and or Pilot Production
68 - the entire core of features
68EC - Embedded Controller without the MMU
68LC - no internal MMU or internal FPU
RC - Ceramic PGA - Au/Pb finish
RP - Plastic PGA
FE - Quad Flat Package
FG - Thin Quad Flat Package
16 - 16MHz
25 - 25MHz
33 - 33MHz, and so on
B - First revision
C - Second revision
D - Third revision (?)
E - Fourth revision (?)
EDIT: I made a new resource here on identifying the 68k CPUs.
MC - Fully Certified
XC - Engineering Sample and or Pilot Production
68 - the entire core of features
68EC - Embedded Controller without the MMU
68LC - no internal MMU or internal FPU
RC - Ceramic PGA - Au/Pb finish
RP - Plastic PGA
FE - Quad Flat Package
FG - Thin Quad Flat Package
16 - 16MHz
25 - 25MHz
33 - 33MHz, and so on
B - First revision
C - Second revision
D - Third revision (?)
E - Fourth revision (?)
EDIT: I made a new resource here on identifying the 68k CPUs.
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Thank you this is incredibly useful. One more question…. The best way to lift that chip . I have a full rework station. But I am wondering if chip quick would be easier. I have never lifted a chip tha size .
I agree that is a valid technique but I have been practicing on a board and I can’t seem to uniformly heat the pins quick enough to lift it . I don’t have the square hot end fittings I have seen used by professionals. Maybe someone can point me in a direction to find them . I will mainly be working on classic and vintage macs as I have a few in the collection!
This should be:
68EC - Embedded Controller, no MMU, no FPU
68LC - no internal FPU
(the LC variants do have a MMU)
@François, thank you for pointing that out. I will fix that tomorrow in the resources.
EC has MMU. Recall that 68030 and 68040 have MMU, so the EC and LC have MMU. The EC does not have FPU and cannot do software-based floating-point operations.
EC is for embedded systems that do not need any floating point operations.
Right. However, it can do software-based floating-point operations via emulation mode.
EC has MMU. Recall that 68030 and 68040 have MMU, so the EC and LC have MMU. The EC does not have FPU and cannot do software-based floating-point operations.
EC is for embedded systems that do not need any floating point operations.
Right. However, it can do software-based floating-point operations via emulation mode.
No, @François is correct. The ability to emulate FP by SW is part of the specifications, although some XC68LC040 have a bug and it doesn't work properly. All MC680LC040 and MC68EC040 should be able to do it properly.
LC have an MMU and are theoretically usable with e.g. NetBSD (though it requires FPU emulation so XC68LC040 are an issue) in addition to MacOS.
EC have neither MMU nor FPU. They are useless in Macs, which expect the MMU to be present.
See M68040 User’s Manual appendix A (LC) and B (EC).
Hi @Melkhior, thank you for clarifying. I will update for sure!
Correct, the 680LC40 has the specification to fetch the address of the exception to emulate FP by software, as explained on page A-6 of the manual as revised by NXP in 2000:
Yeah, the XC is not certified by Motorola, as it is an engineering sample or pilot production that is not fully vetted. Apple may have implemented the XCs as a cost-cutting measure or in a rush. So, that makes sense about the bug.
Interestingly, I read here that "the MC version is a later revision of the 040 which is more tolerant to heat and overclocking than the XC version."
Yep, I agree.
Ah. I see that now on page B-2 of the manual that two access control units (ACU) replaced the MMU in the 680EC40.
Thank you!
I will update for sure!Correct, the 680LC40 has the specification to fetch the address of the exception to emulate FP by software, as explained on page A-6 of the manual as revised by NXP in 2000:
The information is provided so that the instruction is available for software emulation of floating-point instructions. The processor generates exception vector number 11 for the unimplemented F-line instruction exception vector, fetches the address of the F-line exception handler from the exception vector table, and begins execution of the handler after prefetching instructions to fill the pipeline.
Yeah, the XC is not certified by Motorola, as it is an engineering sample or pilot production that is not fully vetted. Apple may have implemented the XCs as a cost-cutting measure or in a rush. So, that makes sense about the bug.
Interestingly, I read here that "the MC version is a later revision of the 040 which is more tolerant to heat and overclocking than the XC version."
Yep, I agree.
Ah. I see that now on page B-2 of the manual that two access control units (ACU) replaced the MMU in the 680EC40.
Thank you!
I updated the 68000 series identification guide in resources to reflect the discussions above.