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SBC6120-RetroBrew Computers Edition - KiCAD, Gerber PCBs & Partial IC Kits

MarsMan2020

Experienced Member
Joined
Dec 19, 2013
Messages
188
Location
Hawthorne, CA
There's a progress update here with some fun pictures of how everything is coming together.

Please read the 'Important Note on HD-6120s' section for some details on the HD-6120 chips that I was able to procure - it's important to me that everyone be happy with what they receive :)
 

acollins22

Experienced Member
Joined
Mar 12, 2007
Messages
248
Location
Leicester, UK
Hi,

That looks like great progress. I am really looking forward to getting my hands on one of these but don't rush. When they are ready will be soon enough.


Cheers,

Andy.
 

hideehoo

Member
Joined
Aug 4, 2015
Messages
44
Location
Prior Lake, MN
Finally found some time to get mine assembled. Came up right away once I figured out the IDC to DB9 cable was not wired correctly, initially it was just throwing garbage on the terminal screen.

IMG_20170123_201400277.jpg
 

MarsMan2020

Experienced Member
Joined
Dec 19, 2013
Messages
188
Location
Hawthorne, CA
Finally found some time to get mine assembled. Came up right away once I figured out the IDC to DB9 cable was not wired correctly, initially it was just throwing garbage on the terminal screen.

View attachment 35667

Nice! Now go play some PDP-8 Adventure :)

As far as my boards and kits go - I have 42 'Hard to find IC' kits tested out of 63 on the original list of interested parties. My day job has been kind of hectic lately, but progress has been steady and I should have things wrapped up soon to start shipping out. Want to get them all tested to make sure everyone will get the kits they asked for before I start shipping.

Andrew B.
 

tingo

Veteran Member
Joined
Aug 12, 2009
Messages
1,480
Location
Oslo, Norway
I got my PCB plus hard to find IC kit from Andrew a few days ago, now I must order the rest of the parts so I can start soldering. Fun times!
 

Tor

Veteran Member
Joined
Mar 14, 2011
Messages
984
Location
Norway/Japan
Yep, got mine on Friday. I'm in the process of collecting the parts, it'll take some time - digi, mouser, or UK equivalents aren't very practical (read: They're costly, due to shipping), so my parts have to come from ebay, ali, and the occasional east european shop. Right now the oscillators seem to be the trickiest parts to find, mostly because I have never known much about canned oscillators and don't know what's equivalent to what.
 

Oscar

Experienced Member
Joined
Sep 11, 2003
Messages
205
Location
Switzerland
The board is VERY nicely made. Gold-plated solder pads as well!
Just did most of the soldering on mine. Only a few parts I have to order.

Maybe one question: HCT logic ICs will not work well? It has to be HC?

Kind regards,

Oscar.
 

tingo

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Joined
Aug 12, 2009
Messages
1,480
Location
Oslo, Norway
Tor, Digi-Key (digikey.no) has free shipping if you order for enough money. You still have to pay VAT when the package arrives, but free shipping is still something. And they had almost all parts in stock (I only had to substitute a few of the sockets).
 

Tor

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Joined
Mar 14, 2011
Messages
984
Location
Norway/Japan
Tor, Digi-Key (digikey.no) has free shipping if you order for enough money. You still have to pay VAT when the package arrives, but free shipping is still something. And they had almost all parts in stock (I only had to substitute a few of the sockets).
The VAT thing implies a customs handling charge too, so it becomes expensive. I vastly prefer to always stay below the NOK 350 limit.
And last time I ordered from DigiKey w/free shipping, FedEx or whatever it was who handled the customs charged me VAT for the free shipping as well. They figured that the "free" shipping was a gift that was taxable. Of course it wasn't, because the shipping is obviously covered by the goods you buy, otherwise it wouldn't be "free". But there's no use arguing with those people. In any case, I don't want to go there again.
 

tingo

Veteran Member
Joined
Aug 12, 2009
Messages
1,480
Location
Oslo, Norway
Understandable. Today, I received my package from Digi-Key. They were quick to pack and ship, and UPS was quick to deliver. As I didn't pay anything when I picked up the package from a nearby UPS delivery point, it is currently unknown how much they will charge me for VAT and handling.
Unfortunately, I had been too quick while punching in my order; I only ordered one SRAM chip. So now I'm looking at eBay and other places for one more.
 

dfnr2

Experienced Member
Joined
Dec 6, 2011
Messages
425
Location
Dallas, TX
Got my kit a bit over a week ago. The board looks very nice. I had to put the kit in the "to do" box, sadly. I hope to build it up before too much time passes. . .

Dave
 

legalize

Experienced Member
Joined
Mar 24, 2006
Messages
387
Location
Salt Lake City, UT, USA
Man, does that sound familiar. I still need to order the remaining parts and solder up the STG board I bought. I'm getting closer, though. Just got myself a nice Hakko soldering iron and some other tools to setup a little electronics bench in my basement.
 

MarsMan2020

Experienced Member
Joined
Dec 19, 2013
Messages
188
Location
Hawthorne, CA
The board is VERY nicely made. Gold-plated solder pads as well!
Just did most of the soldering on mine. Only a few parts I have to order.

Maybe one question: HCT logic ICs will not work well? It has to be HC?

Kind regards,

Oscar.

I always go with ENIG on boards that I might ship to fellow hobbyists overseas just to avoid any chance of a customs snafu with the ROHS rules. :)

I've only tested with HC per the original User's Manual. HCT chips have TTL compatible input voltage levels instead of HC CMOS inputs & are intended for interfacing between TTL & CMOS circuits. Using them in an all-CMOS situation would result in decreased noise tolerance due to the wider input voltage ranges, but other than that I can't think of a physical reason it just wouldn't work.

The POST code in the BTS6120 monitor is pretty comprehensive, so if I had HCT chips on hand I'd probably give them a try first and see what happens. Try 5 Mhz CPU first & let us know how it goes. If we someone finds HCT works, I can add a note to the wiki.

We did have a problem with noise on the original Rev 0.99 prototype board when a tester tried to use 2 74ACT373s and the board would hang partway through POST - but I made a bunch of changes in the routing rules and fill zones on Rev 1.00/1.10 that made it more robust and even those 2 exact problem chips ran fine (at 5 Mhz) the with final design. (I can't thank the guys on the RBC forums enough for helping with testing!). Still, I'd stay away from the ACT series as a result of this experience.
 
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