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Tube🌱Time

the chip pins are crimped. this is a huge pain even with the super nice desoldering tool (FR-301)
14 April at 20:06 | Open on mastodon.social
25 comments
Tube🌱Time

removed the one PROM chip and, confirmed, it was a pain. the other chips will be easier though...
14 April at 20:22 | Open on mastodon.social
Tube🌱Time

just clipping the leads of the chips using side cutters will make this much easier. they're just plain TTL anyway.
14 April at 20:33 | Open on mastodon.social
root42
Darryl Ramm

@tubetime Just makes those chips slightly harder to resell on EBay 🙂

14 April at 20:46 | Open on hachyderm.io
Tube🌱Time
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.

twitter.com/TubeTimeUS/status/

15 April at 23:01 | Open on mastodon.social
vk3kri

@tubetime
Some decades ago I filed a 16 pin DIP desolderer from a lump of copper , with a bit that fit a normal soldering iron. Not hugely sucessful as the irons I had then didn't really have enough power to get it hot enough. The cut all the pins off and desolder one by one method won in the end.

15 April at 23:16 | Open on mastodon.radio
Jeff Haluska

@tubetime With as much de soldering that you do, I'm surprised you don't' already have one.

16 April at 1:07 | Open on mastodon.social
Tube🌱Time

phew, that was a lot of work.
19 April at 21:04 | Open on mastodon.social
Tube🌱Time

scanned and loaded into Kicad!
19 April at 21:32 | Open on mastodon.social
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?

19 April at 22:00 | Open on theblower.au
Tube🌱Time

routed (except for a few RAS and CAS lines). i also have the schematic, but it needs cleanup work.
20 April at 23:34 | Open on mastodon.social
Tube🌱Time

dumped the PROM. it seems to be part of the address decoding process or memory mapping.
21 April at 0:59 | Open on mastodon.social
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.

21 April at 2:05 | Open on mastodon.social
William D. Jones

@tubetime Ahhh, so it's like the AST RAMpage 286 :D!

21 April at 2:06 | Open on mastodon.social
Tube🌱Time

well crap, this board appears to be a clone of the Intel Above Board Plus 8 card. it sure looks the same!
21 April at 2:06 | Open on mastodon.social
Tube🌱Time

yeah sure looks identical. welp, now we know how it works, lol.
21 April at 2:11 | Open on mastodon.social
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.

github.com/schlae/XebecAboveBo

21 April at 18:00 | Open on mastodon.social
root42

@tubetime but has it ever been reverse engineered before…? That would be a bummer. But if not: success!

21 April at 6:30 | Open on chaos.social
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.

21 April at 3:27 | Open on mastodon.sdf.org
Tube🌱Time

@keelan i'm running a trace in layout, seeing where it goes, then creating the connectivity in the schematic and pushing it to layout to create the connection.

21 April at 3:42 | Open on mastodon.social
UpLateGeek

@tubetime RSVP all those legless chips. May their logic live on in the schematic, and in your future clones of their board!

19 April at 22:56 | Open on bitbang.social
Jeff Haluska

@tubetime I suspect that this will be the hardest part of this project.

19 April at 23:58 | Open on mastodon.social
Taki

@tubetime when I was a kid and new parts where out of reach, as well as a desoldering pump, I used this 👇, googles and an old jacket. Melted the solder in a region and hit my hand with the PCB on the table, with the parts side down. Inertia did the rest...
19 April at 21:23 | Open on mastodon.social
Tube🌱Time

@old_Taki good idea but i don't want to burn the board.

19 April at 21:32 | Open on mastodon.social
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