not sure if i have bad 4116's still will look On Fri, Sep 13, 2019 at 5:14 PM Jeffrey Birt <bir...@soigeneris.com> wrote:
> It depends on if my insurance company quits fighting paying for the > procedure or not. I'm planning on not being able to make it still. I would > be happy to pay for postage. > > Jeff > > -----Original Message----- > From: M100 <m100-boun...@lists.bitchin100.com> On Behalf Of Josh Malone > Sent: Friday, September 13, 2019 7:00 PM > To: m...@bitchin100.com > Subject: Re: [M100] In search of bad DRA< - 4164, 41256, etc. > > I've got several bad 4164s -- Microns pulled from an Apple 2 repair. > Are you still unable to make it to TASM? I can post a couple to you if so. > > -Josh > > On Fri, Sep 13, 2019 at 7:54 PM Jeffrey Birt <bir...@soigeneris.com> > wrote: > > > > I built a DRAM tester for fun and to brush up on Arduino development. I > have a lot of students I work with use Arduino, so I wanted to build > something to stay up to date and I have not done anything with an Arduino > for more than a year. I found a project online as a starting point and > added an automatic DRAM refresh driven by Timer2 overflow. Even with a > pokey Arduino and the ISR in C it can refresh 64 rows in less and 100us. > > > > I did a quick test with a 41256 just now and was happy I could > read/write all bits successfully. Then I realized I don’t have any known > bad 4164/41256 type DRAM chips on hand. So, if you happen to have a few bad > DRAM chips on hand and you’re in the USA I would gladly take them off your > hands. Otherwise I’ll have to figure out a way to inject a simulated fault. > Maybe writing a wrong value to a known cell after writing the proper > pattern to all cells would be a good enough simulation? > > > > I still have a way to go with the software. The original project I found > online used separate functions for each test pattern. I want to create a > single function that will write a bit pattern that is passed to it and then > verify that pattern is in memory. Maybe a n second pause would be good to > have in place between the write and verify to ensure that the refresh is > working properly? > > > > Thanks, > > Jeff Birt > > > > > > > >
