one of today's pickups is this mystery Xebec RAM card. I can't find any information about it, so I think I'll try reverse engineering it.
Tube🌱Time
one of today's pickups is this mystery Xebec RAM card. I can't find any information about it, so I think I'll try reverse engineering it. 31 comments
Tube🌱Time
the chip pins are crimped. this is a huge pain even with the super nice desoldering tool (FR-301)
Tube🌱Time
removed the one PROM chip and, confirmed, it was a pain. the other chips will be easier though...
Tube🌱Time
just clipping the leads of the chips using side cutters will make this much easier. they're just plain TTL anyway.
Tube🌱Time
the sockets are going to be trickier. i'm thinking i need a soldering iron tip that can hit all the pins at once. did a web search and the 5th result was MY OWN DANG TWEET from like 2 years ago, lol. i think i just "Fooned" myself.
vk3kri
@tubetime
Jeff Haluska
@tubetime With as much de soldering that you do, I'm surprised you don't' already have one.
Otte Homan
@tubetime with Stannum melting at 157 °C (100 Pi F), you *should* be able to just dunk the populated PCB into a deep fryer at 180 °C (356 F) and all the chips would just fall out?
Tube🌱Time
routed (except for a few RAS and CAS lines). i also have the schematic, but it needs cleanup work.
Tube🌱Time
so this board looks like it does both XMS (extended memory) and EMS (expanded memory). expanded memory is banked and uses a 64K (iirc) window to access it.
Tube🌱Time
well crap, this board appears to be a clone of the Intel Above Board Plus 8 card. it sure looks the same!
Tube🌱Time
OK, here are the KiCad files. it's not really a fab-able design because there are still DRC errors, but at least the schematic is useful.
Keelan
@tubetime how do you go from PCB layout to schematic? When I did this, I ended up tracing the PCB in a CAD package, the writing a thing that analyzed the lines and spit out a netlist. I then learned that while many tools exist to convert schematics to netlists, I couldn’t find much to go the other way ‘round.
UpLateGeek
@tubetime RSVP all those legless chips. May their logic live on in the schematic, and in your future clones of their board! |
@tubetime There's no switches :o...