The cad files are right up there on oshpark. I did have to sand down the edges a little because the "rat bites" landed right in the middle of the edges, which screws up 2 half-holes on each side. You can see it on 2 of the pictures of the bare new boards before sanding. Just zoom in.
As for spacer, yes, also shown in the pictures. You definitely need a spacer bock to prevent the board from going too far into the socket, beyond the "peaks" of the socket pins. I found some thick paperboard stock at the hobby shop where I got the extraction ribbon from, but you can also just use 3 or 4 layers of cereal box. I just hot-glued the ribbon and card stock. I clipped the backs of the jumper pins close to the board and used the hot glue to level up the ribbon and card stock so the spacer ends up parallel with the board. The ribbon is just common 3/8" ribbon from a craft or fabric store. Michaels in my case. I am not the designer just to be clear. He just whipped this up after I said I wished it existed, supplied the pinout reference, and then I made several suggestions which he did, and then I ordered a set from oshpark and finally now have tested it. I think he's going to make at least one more small change, which is just to make the half-holes slightly larger so the socket pins drop in better. But obviously it's already working as it is. I think some silkscreen indication to show which way the module goes in the socket would be good. There's no good way to key the pcb like how the original molex carrier is keyed, unless you poke holes in the ribbon which would not be ideal. -- bkw On May 26, 2016 11:17 AM, "Mike Stein" <mhs.st...@gmail.com> wrote: > As a matter of fact I was thinking about making a RAM ExtRam clone (poor > man's REX ;-) and was wondering the same thing, how to avoid having to > shear/grind the edges. > > How'd he do that? > > m > > ----- Original Message ----- > From: "Stephen Adolph" <twospru...@gmail.com> > To: "Model 100 Discussion" <m100@lists.bitchin100.com> > Sent: Thursday, May 26, 2016 6:43 AM > Subject: Re: [M100] New option rom module > > > > well that's very interesting; I had assumed that since my layout tool > > would fail the design if I put the board edge down the middle of the > > vias, that no one would build with that error. So, I hand grind REX. > > > > > > On Thu, May 26, 2016 at 6:40 AM, Stephen Adolph <twospru...@gmail.com> > wrote: > >> hey, cool. didnt you get a board violation for putting the board > >> perimeter in the middle of the via? > >> do you need a spacer under the board when in the socket? > >> > >> On Thu, May 26, 2016 at 1:04 AM, Brian White <bw.al...@gmail.com> > wrote: > >>> Just verified a new option rom module design. > >>> > >>> Adapts a 28C256 SOIC to a Model 100/102/200 option rom socket. > >>> > >>> Allows re-programming the eeprom after the chip has been soldered to > the > >>> module. A pullup resistor and a jumper on-board allows > enabling/disabling WE > >>> on the eeprom as needed. > >>> > >>> There is a special programming adapter to make it convenient to > re-program > >>> after soldering the chip, but there's a problem with that, so at the > moment > >>> you can still program (re-program) using a dip28 test clip and manually > >>> arranging 28 jumper wires. Not the most convenient but functional. > >>> > >>> This is essentially the same as "ROMBO" or "MOMBO", but now it's an > open > >>> source design up on oshpark and anyone can get one whenever they want. > >>> > >>> Home/self assembly isn't too bad. You don't need anything but the > parts and > >>> a plain soldering pencil and some flux and solder. The soic chip was > simple > >>> using the "drag technique". It's simple, just search "solder drag > technique" > >>> on youtube. The trick is just the extra flux pooled around for surface > >>> tension. > >>> > >>> https://oshpark.com/shared_projects/4dLqXOs0 > >>> > >>> https://goo.gl/photos/Zs8ZnmDco9BwgDDBA > >>> > >>> -- > >>> bkw >
