iMac superdrive can read bought CDs and DVDs fine, but won't recognise CD ROMs and DVD ROMs.

Urquhart1244 wrote:

• The lens in the drive may get dirty, in the same way that windows may need cleaning, even if untouched. Your room is not a laboratory level clean room, no matter how neat you are.

• Pre-recorded discs are more easily read than recordable discs, because the difference between 0 and 1 has a higher contrast.

Thanks, Urqhart.

That third point about contrast makes sense. I really couldn't think of a logical reason why pre-recorded would somehow magically work but computer burned ROMs fail. You have me convinced.

I have a lens cleaner on order (dismantling iMac and reassembling with glue guns, etc. would certainly be a last-if-ever resort).

I'll post here to say how I got on.

That I don't know, yet. I should have checked when I had it in pieces; it has been a year or two since I last opened up the ancient MacBook Pro (2009) — but their two drives certainly looked pretty similar.

I see that the MacBook Pro's Superdrive is listed as: HL-DT-ST DVDRW  GS23N

The iMac's is almost (but not exactly) identical: HL-DT-ST DVDRW  GA32N

Any advice as to whether that's close enough?

If they are interchangeable, at least that would allow me to verify for sure that the problem (as people here are helping me to appreciate) is definitely with the drive and not the OS. At the end of the day, the MacBook Pro gets less use, and only being able to play films or listen to music might be good enough.

On the other hand, I see I can pick one up on eBay or Amazon for a mere £26 ($30) — which seems pretty **** reasonable (so long as it definitely works).

Well, cleaning the lens with a cleaner disk made no difference. Frankly, I don't think I have it in me to take the computer apart. Apple has made this a discouraging prospect, requiring use of razors, glue, and heat guns. Easier, I suspect, to run an earlier OS and see if it then recognises DVD ROMs.

Frankly, I suspect that it may, since this problem seems to be with all ROMs - CDs and DVDs alike without exception - yet abslutely no published films/music CDs.

Of course, you're right, gary/linda. And I so rarely use the optical drive as storage that it would be no great inconvenience really.

But I must confess that part of what attracted this old Mac veteran (I beta-tested the Lisa) to upgrade and maintain the last superdrived iMac was the idea of a single box into which everything went directly and from which all information and entertainment flowed. 40¢ worth of additional screws would have made this iMac repairable and maintainable for at least another fifteen years.

Perhaps it is only my generation who find it so dispiriting that everything you buy now is designed a) to fail within ten years, and b) to be simpler to replace than repair. From the point of view of extinction rebellion, though, surely it is grotesque that the measure of economic success (GDP) is effectively how many resources you can rip from the ground and return to toxic landfill within any decade.

I do understand conspicuous consumption. If you've got it, why shouldn't you choose to flaunt it — but when a sizeable minority wish to keep their old cars, gramophones and watches ticking over, why would intelligent designers force us not to?

The answer, I suppose, revolves around our interdependence with China, and was coined by Gil Scott-Heron in the early eighties: "What has happened is that in the last twenty years" [now almost fifty], "America has changed from a producer to a consumer. And all consumers know that when the producer names the tune, the consumer has got to dance. "

Farewell Jobs and Wozniak. Ave Trump and Johnson.

Right again.

(Apart from the belt tightening bit: mine is tight; America's should be tighter. Planned obsolescence was never inevitable. The clue is in the word "planned"; that strategy was developed by corporations way back in the fifties, and has been ever more recklessly implemented since then. The inevitable change is in the other direction — and the longer we let businessmen corrupt our government in order to pursue an essentially childish course, the more cataclysmic will be that change. Of course Apple, Microsoft and Dell would respond swiftly to any law which made them responsible for the disposal of waste each time a machine or gadget is repaired or replaced: as I say, a dollar's worth of screws are far cheaper than pitching toxic metals and chemicals into the environment, and our shared municipal services should not be held responsible for the cleanup. The 'free market's sainted Adam Smith warned against corporations' drive to conspire against the general good if people don't hold them to account. Accountants call this particular wheeze "externalisation of costs" and it makes shareholders slightly richer at the far greater expense of everyone else — whether or not they ever chose to be consumers. US citizens need the balls — and the government — to say no.)

Wow, really Mike? Music to my ears.

(— or should that be poetry for my eyes?)

YES! Here is a link for just that operation: https://apple.stackexchange.com/questions/154627/upgrade-mid-2011-27-imac-replace-superdrive-with-ssd-and-create-fusion-drive#154810

Thanks so much for the hint. I take back all my bellyaching about bullying designers and built in obsolescence.

I shall investigate immediately and get back with results.

Now, the first thing I need to acquire is some suction cups....