You have to google the data sheets for any ICs like the flash or sram chips. Every letter means something. The only way to know if a different part number is ok, is to look at the data sheet and see what every letter of the part number means for both the known-good reference and any potential replacement. A single letter can mean something like a reversed pin-out that won't work at all, or might only mean a temperature rating that doesn't matter at all.
Bitchin100 actually has a copy of the data sheet for the flash chip for the rex: http://bitchin100.com/wiki/images/c/c1/Am29F800BB.pdf Go to page 9 of that. Look at what the 2nd "B" means. I don't know if the rex actually cares about that (maybe it's a feature that rex doesn't actually use, and so it doesn't matter how that feature behaves, or maybe it does.), but clearly that letter totally reverses a part of the chips behavior. The other specs are more obvious. We probably don't need military/automotive temperature ranges, although they don't hurt. The notes from Steven say 90us, and so generally that means faster is ok too. And of course we need the tsop package. -- bkw On Sep 22, 2017 2:03 AM, "Jim Anderson" <[email protected]> wrote: > > -----Original Message----- > > > > All the items are available on eBay at much lower prices. > > > > I bought enough parts for 10 Rex units and 5 Quads in May and the total > > cost for the parts was around USD $70. Here are the links (some of the > > prices have increased since I bought), hope you find them useful: > > The link to the Toshiba SRAM was VERY useful, thank you! Part of the > problem I have trying to source this stuff (on ebay or even on other > electronics retailers' sites) without having a BOM in-hand to refer to is > that I don't know which parts are equivalent. The SRAM is *mostly* the > same part number but I have no idea whether the differences in the last > four letters mean there is something different about it that will make it > unsuitable for use in QUAD, you know? > > I didn't end up ordering the Xilinx chips from ebay though because the > per-chip cost after shipping and currency conversion was only slightly > lower than Digikey's price... > > > Some of the items originate from China however they arrived well before > > the boards from OSHpark which took about 14days for my order, however > > YMMV. At least for the US there were no import charges. > > Yeah, that's unlikely for me - most of the stuff I get from China > (especially anything with free shipping) is usually four weeks or more. > > > I would not recommend programming the boards in your beloved Model T so > > many things can go wrong. Just tack on power wires and use a bench > > supply set to 5V. > > I think the suggestion of putting it in the model T to power it was for > those of us who don't have a bench supply. :( What sort of things might > go wrong? > > > The other issue was grinding down the edges of the REX board, watch for > > the through hole plating it has a tendency to fold into the hole and can > > cause problems. I cleaned that out with a small needle file. if you > > Good tip - I wonder if it would work better sanding in a perpendicular > motion rather than along the length of the board edge? I was also > wondering if this could be improved upon (for those who have one) by use of > a finer-grit paper in an orbital pad sander? > > > As they say Slow is Pro! Above all have fun building them, nothing like > > seeing your efforts come alive on the Model T. > > Keeping my fingers crossed. :) > > > > > > > > jim >
