Yup, "OTP" EPROMs. There are microcontrollers of that sort as well, same chips in different packaging. Quartz windows and ceramic packages (which are essentially required for quartz windows) are expensive, whole plastic is cheap. The idea is to develop and debug on erasable EEPROMs, then move to OTP for production with no PCB changes. Of course most of that has been supplanted by flash memory technologies now, but EPROMs are still around. -Dave -- Dave McGuire, AK4HZ New Kensington, PA On May 25, 2016 7:14:46 AM Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
The EPROM on the drive now doesn't have a window. I thought that means it's only one time programmable?
Dave, I'll drop you a line off-list. Thanks for the offer!
-J
On Tue, May 24, 2016 at 11:54 PM, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Yes. The problem with EPROMs forgetting their contents is charge leakage from the floating gates, not chip failure.
I have a metric assload of EPROMs (literally thousands) of nearly every type, especially the really common ones like 2764s, if anyone needs them.
-Dave
On 05/24/2016 11:52 PM, Ian Primus via vcf-midatlantic wrote:
Even if an EPROM has gotten corrupted, the chip itself should still be fine. Just erase and reprogram. I've yet to have a problem with doing this, it's quite rare to have a dead EPROM.
Almost every EPROM I have has been scavenged from some sort of junk board or another. 2764's and 2732's are quite common, should not be hard to find.
-Ian
On Tue, May 24, 2016 at 11:22 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jason Perkins
-- Dave McGuire, AK4HZ New Kensington, PA
-- Jason Perkins 313 355 0085