On Wed, Sep 7, 2016 at 3:43 PM, CuriousMarc <curiousma...@gmail.com> wrote:
> > > On Sep 5, 2016, at 9:30 AM, Josh Dersch <dersc...@gmail.com> wrote: > > > > > > At the LCM, I used an Apple II to test out the Alto's memory -- the > > > Alto II XM uses 4116 RAM chips. I swapped in a row at a time and wrote > a > > > little BASIC program to test for obvious errors. This was > > > time-consuming, but eliminated the obviously bad chips, which helped > immensely. > > > > Oh, that's so simple and clever! Are these 16k chips? I don't have an > Apple II, > > but I wonder if I could use the same trick and plug them in my HP 85 > > for which I just managed to burn the service ROM, which has a memory > > test built in. > > Josh, > I checked, and the mysterious HP 1818-1396 or 1818-0341 RAM chips used in > the HP-85 appear to be NEC uPD416-2 or MOSTEK 16k chips. They appear to be > pin for pin, voltage and speed compatible with the MOSTEK 4116-3 used in > the > Alto. So it looks like I could check the Alto Xerox II-XM RAM chips on my > HP-85. > 8 at a time, that might take a while :-). Thanks for the tip, I'd never > have > thought about it! > Marc > > Yep, the NEC uPD416D's are what we have in the Alto we recently restored. And yeah, it takes awhile, but it's worth the effort :). Have fun! - Josh
