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New Board Development - SBC6120-RBC Edition [message #454] Thu, 07 April 2016 21:27 Go to next message
Andrew B is currently offline  Andrew B
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All - I'm happy to announce the development of a new RBC SBC board, the SBC6120-RBC Edition

This is a re-layout of the Spare Time Gizmos SBC6120 into a 2-layer board routed in KiCAD.

I have setup a page for it on the Wiki here - SBC6120-RBC Edition

For those who aren't familiar with the SBC6120, it is a single board computer using the Harris HD-6120 "PDP-8 on a chip" which can be used to run vintage DEC software such as OS/8, FOCAL, and of course, Adventure! Robert Armstrong of Spare Time Gizmos licensed the design files under the GNU FDL and the software under the GPL, so I've taken advantage of that to create a new version of this workhorse board.

Right now I have a "minimum changes" version of the board already routed in FreeRouter. I've:
*Re-routed the board as a 2-layer board, with double-width traces for VCC and GND and flood-fills for VCC and GND on the top and bottom of the board.
*Added a jumper which allows either 27C256 EPROMS (original design) or 28C256 EEPROMs to be used (one of the address pins goes to a different location on the two chips).
*Made some slight changes to the POST display to allow standard rectangular LEDs to be used, and a slightly different reset switch.
*Tweaked a few locations of things to make the new silkscreens look better.
Everything else is unchanged from the original design.

Are there any other changes anyone would suggest before I go to prototypes on this?

[Updated on: Thu, 07 April 2016 21:28]

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Re: New Board Development - SBC6120-RBC Edition [message #457 is a reply to message #454] Fri, 08 April 2016 13:57 Go to previous messageGo to next message
Wayne W is currently offline  Wayne W
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Sounds great Andrew.

Is your new board entirely compatible with the form factor of the original? I have one of Bob Armstrong's SBC6120's with a front panel, but I like some of the changes you are making (especially the EEPROM). I might be interested in swapping the host board and/or just having a working spare.

-Wayne
Re: New Board Development - SBC6120-RBC Edition [message #458 is a reply to message #457] Fri, 08 April 2016 15:13 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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The overall board footprint, mounting holes, and expansion/IDE/Serial connectors are all in the exact same locations. (I don't have the FP6120 front panel or the IOB6120 I/O expansion board, but I want to maintain compatibility with them)

The LEDs and reset switch shifted a little bit.

I'm also looking at switching the RAM from qty 3 64k x 4-bit HM6208s to qty 2 512k x 8-bit AS6C1008. The larger 32-pin 0.600" wide ICs will require moving a few of the other ICs on the board closer together, but if it I can get it to route in a reasonable way it will remove one of the "less standard" parts from the design which I think is a net improvement.
Re: New Board Development - SBC6120-RBC Edition [message #460 is a reply to message #458] Sat, 09 April 2016 17:59 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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Here's a new version with the 2 8-bit-wide SRAMs:

index.php?t=getfile&id=42&private=0

I think this is what I am going to go forward with for prototypes.

Re: New Board Development - SBC6120-RBC Edition [message #461 is a reply to message #454] Sun, 10 April 2016 03:32 Go to previous messageGo to next message
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Any suggestions for where one might source a Harris HD6120?
Re: New Board Development - SBC6120-RBC Edition [message #462 is a reply to message #461] Sun, 10 April 2016 08:17 Go to previous messageGo to next message
Wayne W is currently offline  Wayne W
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UTSource

http://www.utsource.net/Product/Details/HD1-6120-8

That is where I got a couple previously.

Wayne
Re: New Board Development - SBC6120-RBC Edition [message #463 is a reply to message #462] Sun, 10 April 2016 08:33 Go to previous messageGo to next message
pbirkel is currently offline  pbirkel
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Wayne W wrote on Sun, 10 April 2016 08:17
UTSource

http://www.utsource.net/Product/Details/HD1-6120-8

That is where I got a couple previously.

Wayne


Try: http://www.utsource.net/ic-datasheet/HD1-6120-8-701534.html

Although the part-description is a bit ... discouraging :-<.
Re: New Board Development - SBC6120-RBC Edition [message #464 is a reply to message #463] Sun, 10 April 2016 10:11 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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As I've emailed Andrew privately, this is tremendous - Bob Armstrong's design is fantastic, but hasn't been available for some time.

Kudo's to Andrew for reproducing the PC board!

I wouldn't worry about the SRAM personally - the 64Kx4 types have many equivalents. I used Sharp LH52252AD-45's in the boards I built in the past. We could certainly arrange a bulk purchase of CPU/SRAM/GAL's for folks.

The HD1-6120's come in -2, -8 and -9 varieties. All work fine (the only difference is that the -9 is commercial temperature rated, the other two have a slightly wider range.

- Gary
Re: New Board Development - SBC6120-RBC Edition [message #465 is a reply to message #464] Sun, 10 April 2016 10:26 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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The RAM change is something that a lot of people have asked Bob for over the years, since I've got it all routed I'm going to go ahead with it for my initial run of prototypes. If it poses any kind of a problem, we'll go back to the original design.
Re: New Board Development - SBC6120-RBC Edition [message #466 is a reply to message #465] Sun, 10 April 2016 11:34 Go to previous messageGo to next message
will is currently offline  will
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Brilliant, ordered the CPU, please put me down for a prototype board.
Re: New Board Development - SBC6120-RBC Edition [message #467 is a reply to message #466] Sun, 10 April 2016 13:55 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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I'm planning to do a run of 5 prototypes, so far I have Gary and Will and myself down for 3 of them.

Re: New Board Development - SBC6120-RBC Edition [message #468 is a reply to message #463] Sun, 10 April 2016 18:14 Go to previous messageGo to next message
Wayne W is currently offline  Wayne W
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pbirkel wrote on Sun, 10 April 2016 08:33
Wayne W wrote on Sun, 10 April 2016 08:17
UTSource

http://www.utsource.net/Product/Details/HD1-6120-8

That is where I got a couple previously.

Wayne


Try: http://www.utsource.net/ic-datasheet/HD1-6120-8-701534.html

Although the part-description is a bit ... discouraging :-<.


Yeah, I assume the description is just wrong. Not totally unusual for UTSource to have the wrong description or picture. I have never had a problem getting the correct part though. I got two of this exact part from them in January 2015.
Re: New Board Development - SBC6120-RBC Edition [message #469 is a reply to message #468] Sun, 10 April 2016 22:04 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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The 5 prototype boards are spoken for at this point:
Me
Gary (has original STG board as well)
Wayne (has original STG board as well)
John C.
1 gentleman from the Spare Time Gizmos group who contributed a fixed Gerber of the original board to help get this done.

Should be about 2 weeks to get them in.

I am really glad to get this board re-captured into an open source EDA program and available for other hobbyists. It's a very well thought out design and the BTS6120 monitor ROM is very powerful!
Re: New Board Development - SBC6120-RBC Edition [message #470 is a reply to message #469] Mon, 11 April 2016 08:03 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Fantastic!

I should have all parts waiting here for construction. (Just saw new diagrams on the Wiki, using 128Kx8's)

As a follow up project, might be neat to have a S-100 "carrier" board with a simplified front panel that the SBC6120-RBC can piggy-back onto Smile

- Gary

Andrew B wrote on Sun, 10 April 2016 22:04
The 5 prototype boards are spoken for at this point:
Me
Gary (has original STG board as well)
Wayne (has original STG board as well)
John C.
1 gentleman from the Spare Time Gizmos group who contributed a fixed Gerber of the original board to help get this done.

Should be about 2 weeks to get them in.

I am really glad to get this board re-captured into an open source EDA program and available for other hobbyists. It's a very well thought out design and the BTS6120 monitor ROM is very powerful!

[Updated on: Mon, 11 April 2016 12:13]

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Re: New Board Development - SBC6120-RBC Edition [message #471 is a reply to message #470] Mon, 11 April 2016 12:59 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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Changes from the original board in the BOM:

*RAM is 2x AS6C1008-55 (either -55PCN or -55PIN should work).

*POST LEDs are 4x rectangular 5mm x 2mm w/2.54mm lead spacing - Digikey example Jameco example

*Each post LED needs a 150 ohm resistor (yields a 20ma LED current)

*Reset switch is a switch with the spacing between the pins at 4.5 mm, the spacing between the mechanical "legs" at 7.0 mm, spacing between the two sets of holes at 2.5 mm, and a plunger depth of ~5.85-6.00 mm - Digikey example Jameco example (there are several switches which will fit made by different manufacturers).
Re: New Board Development - SBC6120-RBC Edition [message #472 is a reply to message #469] Tue, 12 April 2016 11:54 Go to previous messageGo to next message
Wayne W is currently offline  Wayne W
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Andrew B wrote on Sun, 10 April 2016 22:04
The 5 prototype boards are spoken for at this point:
Me
Gary (has original STG board as well)
Wayne (has original STG board as well)
John C.
1 gentleman from the Spare Time Gizmos group who contributed a fixed Gerber of the original board to help get this done.

Should be about 2 weeks to get them in.

I am really glad to get this board re-captured into an open source EDA program and available for other hobbyists. It's a very well thought out design and the BTS6120 monitor ROM is very powerful!


Sounds great Andrew. I have a couple of spare HD6120 already, so I am good on the hardest to procure part. I will review the rest of the parts list shortly and try to get everything ahead of the board's arrival.

As I reviewed the state of my previous build, the one point of frustration for me was the ROM versions. Based on email's from Bob Armstrong, the latest ROM version is 271 (ignoring a branch of ROM version for the -RC hardware version which is not relevant). However, the only ROM version source/hex files I have ever found are 266. I asked for the latest version on the SpareTimeGizmos Yahoo! Forum some time ago, but radio silence. If you have any contacts that might be able to get us the latest version, that would be very nice. Not a show-stopper since v266 should be quite functional.

-Wayne
Re: New Board Development - SBC6120-RBC Edition [message #473 is a reply to message #472] Tue, 12 April 2016 12:02 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Wayne -

I'm fairly certain I have the 271 version of the ROM at home. I'll check tonight and can upload it to the wiki.
Re: New Board Development - SBC6120-RBC Edition [message #474 is a reply to message #472] Tue, 12 April 2016 12:04 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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My plan is to get a working board and then ask about the source code for v271. Another person (Jim Kearney who designed the IOB6120) contributed code to the monitor ROM at one point and his code is licensed under the GPL, so the source code for the later versions should be made available to anyone who received a binary versions in the ROM.......

v271 fixed some bugs in the fron panel switches/rotary knob, so it would be nice to have that version. Otherwise we'll need to start from v266 and re-create the fixes.

But I think once we have working boards, it's very likely I'll be able to get us a copy of the source.

I'd be hesitant to upload the binary version to the wiki without the source due to the GPLed code.

[Updated on: Tue, 12 April 2016 12:05]

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Re: New Board Development - SBC6120-RBC Edition [message #475 is a reply to message #473] Tue, 12 April 2016 13:10 Go to previous messageGo to next message
Wayne W is currently offline  Wayne W
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gkaufman wrote on Tue, 12 April 2016 12:02
Wayne -

I'm fairly certain I have the 271 version of the ROM at home. I'll check tonight and can upload it to the wiki.


That would be great. I would love to upgrade my current board at this point.

-Wayne
Re: New Board Development - SBC6120-RBC Edition [message #477 is a reply to message #475] Tue, 12 April 2016 14:41 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Wayne -

I uploaded what I think is a later version of the design files to the Wiki at:
https:// www.retrobrewcomputers.org/doku.php?id=boards:sbc:sbc6120-rb c-edition:start

Unfortunately I don't see any source for the v2.71 ROM's, but the .hex files are there.

I'll keep looking thru my somewhat disorganized downloads to see if I have more.

- Gary

Wayne W wrote on Tue, 12 April 2016 13:10
gkaufman wrote on Tue, 12 April 2016 12:02
Wayne -

I'm fairly certain I have the 271 version of the ROM at home. I'll check tonight and can upload it to the wiki.


That would be great. I would love to upgrade my current board at this point.

-Wayne

Re: New Board Development - SBC6120-RBC Edition [message #478 is a reply to message #477] Tue, 12 April 2016 15:25 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Hope it was ok to upload the files to the WIKI, but it's a file that I believe came from Bob's site in the past and includes all of the original license info.
Re: New Board Development - SBC6120-RBC Edition [message #479 is a reply to message #478] Tue, 12 April 2016 15:38 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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Regardless of what was up on Bob's site, if we have a v271 binary on the wiki, we technically need to have the v271 source available as well - since Jim K's code contributions are under the GPL which requires the source be offered with the binary.

I'll take it down later (only admins can delete things right now...)

My plan was to link to the resources on the STG site on the wiki for now until we have working boards at which point I'll make new RBC Edition Design and Source archives for the wiki with all the appropriate license info.

[Updated on: Tue, 12 April 2016 15:39]

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Re: New Board Development - SBC6120-RBC Edition [message #480 is a reply to message #479] Tue, 12 April 2016 16:13 Go to previous messageGo to next message
Wayne W is currently offline  Wayne W
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Andrew B wrote on Tue, 12 April 2016 15:38
Regardless of what was up on Bob's site, if we have a v271 binary on the wiki, we technically need to have the v271 source available as well - since Jim K's code contributions are under the GPL which requires the source be offered with the binary.

I'll take it down later (only admins can delete things right now...)

My plan was to link to the resources on the STG site on the wiki for now until we have working boards at which point I'll make new RBC Edition Design and Source archives for the wiki with all the appropriate license info.


OK, understood. Hopefully, the v271 sources are available. They are definitely not posted on the STG site.

Appreciate your efforts Gary.

-Wayne
Re: New Board Development - SBC6120-RBC Edition [message #482 is a reply to message #480] Tue, 12 April 2016 18:07 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Found the Source for 2.71!

Appended.

Andrew, hopefully we can re-zip this in with the file I previously posted and satisfy the GPL?

- Gary
  • Attachment: BTS6120.PLX
    (Size: 355.60KB, Downloaded 550 times)
Re: New Board Development - SBC6120-RBC Edition [message #483 is a reply to message #482] Tue, 12 April 2016 18:38 Go to previous messageGo to next message
Wayne W is currently offline  Wayne W
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gkaufman wrote on Tue, 12 April 2016 18:07
Found the Source for 2.71!

Appended.

Andrew, hopefully we can re-zip this in with the file I previously posted and satisfy the GPL?

- Gary


Excellent. Thanks Gary!
Re: New Board Development - SBC6120-RBC Edition [message #484 is a reply to message #482] Tue, 12 April 2016 18:51 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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AWESOME! You made my day!

Yeah, as long as they are in the same .zip it will be fine.
Re: New Board Development - SBC6120-RBC Edition [message #485 is a reply to message #484] Tue, 12 April 2016 20:04 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Ok, updated the .zip file on the WIKI to include the source.

Sometimes being a pack rat pays off Smile

- Gary
Re: New Board Development - SBC6120-RBC Edition [message #486 is a reply to message #485] Wed, 13 April 2016 01:05 Go to previous messageGo to next message
computerdoc is currently offline  computerdoc
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Hi Gary,
I agree Gary! I wish I could convince my family that being a pack rat is a good thing. Smile


Kip Koon
computerdoc at sc dot rr dot com
http://www.cocopedia.com/wiki/index.php/User:Computerdoc
Re: New Board Development - SBC6120-RBC Edition [message #533 is a reply to message #486] Tue, 19 April 2016 10:05 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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I received the shipping notice that the prototype boards are on their way to me via DHL Express from Hong Kong. Since I am on the "left coast" (15 minutes from LAX) I expect they will be in my hands by the end of the week.

I spent the weekend searching over 50 independent stocking distributor websites in the US hoping to find some HD1-6120-2,8,9s for this project from a source other than China. A handful (~5) supposedly had stock. So far only one distributor has replied to my RFQs saying they had any of them available, and they wanted $75 each Sad

Re: New Board Development - SBC6120-RBC Edition [message #534 is a reply to message #533] Tue, 19 April 2016 10:50 Go to previous messageGo to next message
jcoffman is currently offline  jcoffman
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I have found both the 6120 & 6402 on eBay for $16 & $5, respectively. Both, of course, are coming from China.
Re: New Board Development - SBC6120-RBC Edition [message #535 is a reply to message #534] Tue, 19 April 2016 11:03 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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Jameco has the 6402, they are pulls but I'd trust them over China - http://www.jameco.com/webapp/wcs/stores/servlet/Product_1000 1_10001_43158_-1
Re: New Board Development - SBC6120-RBC Edition [message #536 is a reply to message #535] Tue, 19 April 2016 11:24 Go to previous messageGo to next message
rhkoolstar is currently offline  rhkoolstar
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u-barn? they shipped me 2 bogus Z80 SIO chips. After I complained I got the right ones.
Make sure you check the wares

RHK
Re: New Board Development - SBC6120-RBC Edition [message #537 is a reply to message #535] Tue, 19 April 2016 11:26 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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I also believe that many 5v only standard UART will interchange. Fortunately I have a few 6402's in the parts draw.

I've purchased 6120's from China in the past, and just received one from UTSource last night. I'll test it shortly and report back to the group, but it looks like a clean new part.

Excited to get the board, all parts are now here...

- Gary
Re: New Board Development - SBC6120-RBC Edition [message #539 is a reply to message #537] Tue, 19 April 2016 15:37 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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Delivery date is confirmed as Thursday (6/21).
Re: New Board Development - SBC6120-RBC Edition [message #541 is a reply to message #539] Wed, 20 April 2016 03:49 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Tested the Intersil HD1-6120-8 from UTSource last nite, worked fine in a SBC-6120 using 5mhz clock (higher speed not tested).
Purchased thru their phone app, so after 10% discount price was $18.75 + $2.00 shipping. 14 days to arrive.
Re: New Board Development - SBC6120-RBC Edition [message #543 is a reply to message #541] Wed, 20 April 2016 08:34 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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Could you post some pictures of the chip? I'm curious, I feel like they may be remarked (Harris only became Intersil in 1999, which I believe was after the 6120 was discontinued) but I can't think of why that was needed.
Re: New Board Development - SBC6120-RBC Edition [message #545 is a reply to message #543] Wed, 20 April 2016 11:23 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Looks like the part in auction #311454981484

Light colored ceramic, etched markings, clean pins.

Andrew B wrote on Wed, 20 April 2016 08:34
Could you post some pictures of the chip? I'm curious, I feel like they may be remarked (Harris only became Intersil in 1999, which I believe was after the 6120 was discontinued) but I can't think of why that was needed.

Re: New Board Development - SBC6120-RBC Edition [message #548 is a reply to message #454] Thu, 21 April 2016 20:45 Go to previous messageGo to next message
Andrew B is currently offline  Andrew B
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The boards are here!

index.php?t=getfile&id=45&private=0
Re: New Board Development - SBC6120-RBC Edition [message #550 is a reply to message #548] Fri, 22 April 2016 06:54 Go to previous messageGo to next message
gkaufman is currently offline  gkaufman
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Very nice!
Re: New Board Development - SBC6120-RBC Edition [message #556 is a reply to message #550] Sat, 23 April 2016 15:12 Go to previous messageGo to previous message
Andrew B is currently offline  Andrew B
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Prototype boards shipped out to Gary, Wayne, John & Will today.
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