Klaas Robers wrote:In the past we had EPROMs 2716. And then there came 2708 chips. They had half the storage capacity. But if you tried to program them beyond this limitation, it worked! The 2708 chips were in fact 2716 chips that had "a problem" in the higher part of the memory space. You never knew where it was, so a certain chip would work, while another chip woud cause problems. On the other hand, the faulty 2716's could still be sold as a 2708.
But if there was a problem in the first 8k.....
I expect that there was someting, a bonding pad, that when grounded, inverted the highest address line, so that the second 8k was swapped to the first 8k. During production it was grounded or not.
Steve Anderson wrote:Very little done on this or anything else in almost a month, a major upheaval/re-organisation of my workshop/office has been underway, almost complete. It's amazing the amount of junk one accumulates over just a few years!
But I hope to be 'back on the case' once the weekend is over.
Steve A.
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