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Slot 8 Support Daughterboard for XT-IDE

glitch

glitch

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Feb 1, 2010
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As promised:

1qc0Sbz.png


This is a little bit of board that will get soldered down to the back of the EEPROM footprint. You'll need to make three wire connections to the XT-IDE. Now, I'm sure we're going to get some posts about how this is a stupid project :) But, this little board should work with ALL of the existing N8VEM XT-IDE boards, unless you've got one of the XT-IDE rev 1 boards that doesn't have the /CARDSEL edge pin on the connector.

Ordered boards from OSH Park, 3 boards cost less than $5 shipped. Yes, it's surface mount, but I'll be providing them assembled as well as kit form. Of course, if you want one installed on an XT-IDE board I can do that at assembly time, or you can mail me an existing board and I'll tack it on for you. If you've never tried surface mount soldering, this board should be about as easy as it gets -- 1206 resistors and capacitors, and a 14-pin SOIC chip. Solderable with a 15 Watt Rat Shack iron.

Once it's verified working, I'll probably order a panelized batch to make my assembly easier. KiCad project files will of course go up on GitHub once it's verified.
 
That looks awesome. Let us know when you are ready for beta testers. Kits would be great, but I'd be willing to source my own parts if that would make it easier. When you mentioned the tabs to secure it, I assumed they would be just for mechanical attachment but your image looks like they make electrical connections to the eprom. Am I correct?
 
ibmapc said:
That looks awesome. Let us know when you are ready for beta testers. Kits would be great, but I'd be willing to source my own parts if that would make it easier.
Click to expand...

I'll just plug it into my IBM 5160 PC/XT and see if it works, no need for others to test it when I've still got some of the tin plated XT-IDE rev 3 prototype boards to experiment on :) It should work fine, it's not that complicated of a thing -- you're just signalling a bus driver on the XT motherboard to turn on. I don't suspect this will be in huge demand, but you're certainly welcome to one of the purple OSH Park prototypes if you'd like!

ibmapc said:
When you mentioned the tabs to secure it, I assumed they would be just for mechanical attachment but your image looks like they make electrical connections to the eprom. Am I correct?
Click to expand...

Yep, that's right! Inspired by some of the console mod chips I've seen :) I may have the attachment holes v-scored so they can be snapped into a half-pad when removed from the panel. I figure this way there's no gluing and four less jumper wires. Plus for people who don't want to try surface mount at home, I can provide this as an assembled module, and you can still build the rest of the XT-IDE yourself.
 
Is there a way to add a jumper to disable it if one wants to take the card out of slot 8 and put it in another slot or a clone? Since the daughter board will be on the solder side, the jumper would need to be bent over so that it would not interfere with other cards. Is that necessary? Or can the "Slot 8 mod" stay active when used in other than 5160 slot 8?
 
ibmapc said:
Is there a way to add a jumper to disable it if one wants to take the card out of slot 8 and put it in another slot or a clone? Since the daughter board will be on the solder side, the jumper would need to be bent over so that it would not interfere with other cards. Is that necessary? Or can the "Slot 8 mod" stay active when used in other than 5160 slot 8?
Click to expand...

Even better -- I was going to write up the instructions to have users route it through the eigth switch on SW2, it's unused and I left both ends disconnected.
 
Because I apparently can't leave a design alone, I'm working to do the legends as solder mask relief so I can run the board with no silkscreen. One manufacturer I use does excellent photolitho but their silkscreen is awful. If I can use them by getting rid of the silkscreen, I can get the cost per board down around $1. I feel like this should be a $1 board.

EDIT: Results are now!

ys6o4gt.png


Think I'll order them both ways. The nice thing is, you can export the Gerbers either way, so if people in the future need to run them and do it through e.g. OSH Park, they can just use silkscreen if they like.
 
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SkydivinGirl said:
Will this work on the old XTIDE Rev 2?

http://www.vcfed.org/forum/showthread.php?29202-XTIDE-Rev2

Looks nice!

Heather
Click to expand...

As long as it has all of the gold edge fingers -- I don't know if any rev 2 boards were made with the unused fingers removed, like some of the rev 1 boards. I have a few rev 2 boards here, I plan to test on one to get a definite answer and write up instructions. I'll have to look at the schematic, but it may not work with the built-in serial port.

EDIT: Just looked over the rev 2 schematic, it will be slightly different than installation on a rev 3 or rev 1 card but it should fully work including the built-in serial port!
 
Added the parts onto today's Mouser order. My prototype quantities are probably sufficient for parts kits! I bought enough for 10 boards.
 
Mouser parts arrived today, everything looks correct! I also ordered some parts for measurement confirmation for another sort-of XT-IDE related project :D

OSH Park says they expect the board back by 28 SEP. I'll dig out my IBM 5160 PC/XT by then.
 
Boards have shipped! They'll probably be in Tuesday or Wednesday next week. That gives me plenty of time to build a few up and test in my PC/XT that weekend.
 
Boards are in!

ek3nOCi.jpg


I used my Stickvise (stickvise.com, you can buy through the Hack a Day store) to assemble. If you don't have one, just solder the board down to the XT-IDE first.

K3NGHR5.jpg


Surface mount components installed. Notice that I filed the ends off of the mounting through-holes. I plan on having the final version routed so that the holes come from the fab already cut in half. I think I will reposition the R1 legend, the copper break in the middle makes it far less readable than I was hoping.

tzczLZ8.jpg


Mounted to the back of the board behind U10. It helps to remove the solder from U10 pins 14, 20, 22, and 28 to get the daughterboard flat against the XT-IDE board. I just used a bit of solder wick, no need to fire up the vacuum station.

kBp8TC8.jpg


All wired up! Notice how TP1 on the daughterboard goes over to SW2? This lets SW2, switch 8 disable/enable Slot 8 functionality. This is a prototype rev 3 board, so there's no test point for the /CARDSEL pin. Production rev 3 boards (what everyone who bought one from me received) have a solder pad so you won't need to tack on to the edge finger. Rev 2 boards will need tacked on to the edge finger. Rev 1 boards will as well, if you've got one that has all of the edge fingers populated -- the ones I've got don't.

I don't have my IBM 5160 PC/XT set up at the moment, I'll dig it out this weekend and test. I'll build up another for the rev 2 card I've got and test with that as well.
 
glitch said:
... Rev 1 boards will as well, if you've got one that has all of the edge fingers populated -- the ones I've got don't...
Click to expand...

My Rev 1 Boards don't either, IIRC it was only the very early prototype Rev 1 boards that had all the fingers and the unused fingers got removed a bit later on in the stage, before the main production run.

Nice looking mod :)
 
Didn't have time to dig out the XT this weekend, should be able to get it tested next weekend. Glad to see people are interested in it :)
 
Finally had time to test, it works fine with the rev 3 boards! I'll put together a rev 2 test tonight or tomorrow evening and test with the serial port.
 
Works with the Rev 2 board, and the wiring is even cleaner than the Rev 3 board! It's like I meant it to work like that :) I'll post pictures and a full write-up later.

Since I'm not sure how much interest there's going to be in these boards, if you're interested in one, would you be OK with buying a prototype run board? They work fine, and are high-quality OSH Park Made in the USA items.
 
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