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1088XEL Alternative Mother-Board Project


mytek

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I´m just curious... wha´s for an PCB layout program you´re using?

 

Jurgen

 

I'm using the ExpressPCB schematic capture and PCB layout programs. Manual routing only. So yes a bit more work on my part, but believe it or not I find it oddly satisfying. I route a section at a time until I'm bored, and then just pick it up at another time. In the past I have used Eagle and it's autorouting feature, but I remember having to do a lot of fine tuning to the layout afterwards to get things to where I wanted them to be. Also my brain ages, and due to the infrequency of using PCB layout programs, I like the simplicity of ExpressPCB vs trying to remember how to do something in a more complicated program. Call me crazy :-D

 

- Michael

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I'm using the ExpressPCB schematic capture and PCB layout programs. Manual routing only. So yes a bit more work on my part, but believe it or not I find it oddly satisfying. I route a section at a time until I'm bored, and then just pick it up at another time. In the past I have used Eagle and it's autorouting feature, but I remember having to do a lot of fine tuning to the layout afterwards to get things to where I wanted them to be. Also my brain ages, and due to the infrequency of using PCB layout programs, I like the simplicity of ExpressPCB vs trying to remember how to do something in a more complicated program. Call me crazy :-D

 

No, I won´t :P

 

Thanks for feedback. I´m always curious to find out what other hardware wizards are using. I take a look at DipTrace for example, but this program is not my best friend. I´m using Eagle for years, but the last three projects I also start to route manually or route all power traces and important signals (video, audio etc.) by hand and let the autorouter make the rest on data-/adresslines. My intentions is also "a silly one": It looks better ;-)

 

Jurgen

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No, I won´t :P

 

Thanks for feedback. I´m always curious to find out what other hardware wizards are using. I take a look at DipTrace for example, but this program is not my best friend. I´m using Eagle for years, but the last three projects I also start to route manually or route all power traces and important signals (video, audio etc.) by hand and let the autorouter make the rest on data-/adresslines. My intentions is also "a silly one": It looks better ;-)

 

Jurgen

 

I totally agree with that last statement about it looking better ;-)

 

Also reliability is key. I like to run stuff under Linux and/or Wine in Linux, and ExpressPCB is absolutely rock solid with this set-up, never crashing. When you're routing traces this is extremely important. Even loosing the last 10-15 minutes of work can make you cry :_(

 

- Michael

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Milestone Acheived!!! PCB Layout Completed

 

XJFFbJP.png

 

1WGLVg4.png

 

Updated Schematic and PCB Design View Document: 1088XEL_V1_X_3-20-2017_schema.pdf

 

Believe it or not, I was able to use 12 mil traces and inter-track spacing on about 99% of the layout, only needing to drop down to 8 mil traces for a few of the tighter spots. For me this board marks an achievement in my life, being the most complicated PCB that I ever laid out, and likely will hold that record for the rest of my life ;)

 

Yesterday I was showing Bob Woolley where this project was at, and he asked me if I was going to make an announcement when I had completed the board routing (at the time I was only 1 trace route away from completion). I said probably not until I had a completed 'working' board in my hands. Obviously I rethunk that. What made me change my mind was that this project has been disclosed bit by bit through out this topic, sharing my journey in the process. I thought... why stop doing that? If it fails to work when I get my first boards, that too is a part of this journey, and you'll see me grumble and then sit back down and fix whatever is wrong :grin:

 

Design Changes

 

There have been some minor changes. For one thing I had the logic backwards on the power control circuit related specifically to what state the gate of the P-Channel MosFet (Q1) needs to see to turn on. That happens to be GROUND and not +5 as I originally presumed. So luckily I was able to correct this oversight by doing a slight reconfiguration of the existing circuit where I had already provided an NPN transistor to optionally switch on an ATX style PSU (LOW = ON). Now I share that inverted output. The other change worth noting is that what I was calling my EUI (Enhanced Upgrade Interface), now has a new name and a new pin assignment. Basically I can thank Bob for giving me the idea of also including the /$D1xx select signal, so that in essence this thing really is a mini version of something akin to the PBI. So now I call it MPBI (Mini Parallel Bus Interface). Basically it provides an abbreviated version of a full PBI, and also provides some additional page select bits and a few other goodies as well. Its interface connector is a 30 position 0.1" pitch double row header, which is easily connected to via a ribbon cable. In its new form, it provides signals for both the Rapidus and VBXE, and makes for a simple parallel port as well. For full parallel bus applications, I have retained the original ECI card edge connection.

 

There might have been a few other changes, but it all becomes a blur after putting in hours and hours of layout time. Download the attached PDF file to see where the 1088 XEL is presently at. It also includes the board front and back images as above, but you'll be able to zoom in for a much finer detail.

 

What's Next?

 

After taking a few more days to verify that everything is good from a design rules standpoint, I'll be ordering 10 boards. Some of these will make there way into the hands of a few beta testers I've used in the past on some of my other projects, and the rest will be for me to stare at in wonder as I think "Where the heck did I find the time and the drive to take on such a project!" And of course I'll put a few to actual use, creating a couple of cased Mini-ITX systems to play with (and eventually demo at a future Atari gathering).

 

So yet another MIni-ITX Atari motherboard will soon take its place in history :)

 

- Michael

 

 

Edit: I did remember a few of the other changes: Had to correct orientation of pin 1 on several connectors (Joy Sticks, MPBI, and RGB-Thru), also added left channel audio to pin 1 of RGB-THRU which automatically superimposes this signal onto the Sophia D-Sub 9 RGB connector by simply crimping a 10 pin IDC female 1" from where the ribbon cable leaves the Sophia board. BTW, Sophia when connected to my board in this fashion, will still have the originally provided connector as well as being routed out to the DIN-13 jack on the 1088 XEL. So either interface jack can be used for Sophia's RGB output.

Edited by mytekcontrols
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Thank you Stephen :)

 

Yeah I have to pat myself on the back on this one for sure. It's always nice to see a board design get to this stage, because in the beginning the outlook was rather bleak when faced with the enormity of the task at hand. And about a week into it I was seriously reconsidering if I still wanted to do this ;-) Luckily I stumbled across a great helper program for ExpressPCB called eCheck which basically puts in what ExpressPCB lacks, and that is a good verifier tool to insure that everything between the schematic and PCB match net list wise, and also does a Design Rules Check to see if there are any potential manufacturing issues. It's free to use, but since it works so well and saved me lots of headaches, I gladly payed the author's donation fee of $20.

 

xCheck
v2.3

 

xcheck_small2.png

 

Download xCheck

 

 

Yes Mr Fish... I guess I was destined to do this. And if I had these tools and knowledge back in the 90's it would have been a world changing event :grin:

 

- Michael

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A custom 3D printed case would be fantastic :thumbsup: Hopefully we'll see some examples of this emerge.

 

Just for grins I submitted my files to OSH Park to see how much it would cost through their service. Not surprisingly it came to $495 for 3 boards :-o . Their service is geared towards being able to put a lot of mixed boards on a single panel, which works well for something the size of my former projects (TK-II, JOY2PIC, ect). But not so good with something the size of a Mini-ITX motherboard. And although I'll never have the 1088 XEL produced by OSH Park, it's nice to at least have the gerber files backed up there under my account. When I know the board design is solid, I'll enable 'sharing' of the files on that site. But for those that are curious as to what an OSH Park version would look like in all of its purple and gold glory, here you go (click on the image to enlarge it).

 

 

6416fbdd27cbdbe3af1c1500f73c0210.png

 

 

You'll notice that the silk screen has been updated from my last post. I used Copper Connection to enhance a few things, such as add a few more graphics, and smooth out the text.

 

 

 

A little over a year ago the first concept schematic for this project was created, and the idea had been brewing in my mind probably starting 6 months before that.

 

NtJXMqx.png

 

Boy how time sure flies by when you're too busy to notice ;)

 

- Michael

Edited by mytekcontrols
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Good thing I am double checking everything, because I found something on the silkscreen that needed updating (the RGB THRU connector pin assignments).

 

So here are the corrected pin assignments...

 

iLjkZ9b.png

 

As I probably mentioned before, this exactly matches Sofia's ribbon cable connection if you add an additional IDC-10 crimp-on connector about 1" where it leaves the Sofia board (making sure that pin 1 lines up, since there is one unused position). The RGB THRU passes the signals on to the DIN 13 Jack on the rear side of the 1088 XEL board, and should be pin-for-pin compatible with an ST color monitor (VBXE boards can also use this same RGB THRU to also have their RGB output passed on). For those that don't know what Sofia is (which is unlikely), it is a recreation of the GTIA chip in CPLD having a selectable RGB or Component video output (Link to Sofia Topic). It's a cool little board that greatly improves the A8 video experience, yielding super clean video output.

 

Sofia: GTIA in CPLD

 

post-26134-0-97810000-1484002601.jpg

 

- Michael

Edited by mytekcontrols
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The bullet has been bit! First 1088 XEL board order was submitted today. Well I guess my time machine is also working since the receipt is dated for tomorrow (China time).

 

ObZ1QFj.png

 

Layout that was sent to be manufactured...

 

Hi Rez Image of Top Side

HnCFwPg.png

 

Hi Rez Image of Bottom Side

48JuKCr.png

 

Final Version 1.0 Schematics: 1088XEL_V1_0_3-21-2017_schema.pdf

 

I'll be seeing boards within 1 week for an individual cost of $18.28 (much faster than Itead or OSH Park, and very inexpensive).

 

Now I'll just pray that the smoke stays inside the chips when i assemble and test my first one ;)

 

- Michael

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I gotta say, this is incredibly awesome work. What a blast to see this thing go from concept to hardware. You guys never cease to amaze me!

 

Now this is the kind of reaction I truly love to see, and the main purpose behind starting this topic... sharing the journey. Thank you tuf :)

 

On a different subject...

 

So that no one gets their hopes up, this first batch of boards is already spoken for, and will be used for beta testing the hardware. But don't worry once things have been ironed out with the design and all is considered good to go, it appears pretty certain that there will be a future quantity order placed for both the boards and the components that go into it. When that happens, people will be able to join the pre-order. But for the time being that is really all I know about that, since it will be handled by a 3rd party and not myself. I prefer not to get involved with the selling of things, and instead would rather focus on the creation of things.

 

- Michael

Edited by mytekcontrols
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170mm x 170mm 4 layer PCB for $15 each? Wow.

 

Looks great, I can't wait to see your progress as you bring the board up!

 

Well after you kick in the DHL shipping it comes out to $18.28 per board. still a bargain in my book, especially considering that I only had to purchase 10 boards to get that pricing :thumbsup:

 

So in case you missed it. This board will be 4-Layers with independent +5 and GND planes sandwiched in the middle, 2 mil board thickness, 1 oz copper, lead free process, blue solder mask with white silk screen. Basically a professional PCB. I'm hoping that with the independent power planes this ends up being one of the quietest Atari 8-Bit computers ever made, maybe only rivaled by the 1400 series. throw in Bryan's UAV as the composite/S-Video solution and either the VBXE or Sofia and hopefully those video problems that plague the existing 8-Bit series will be totally and completely gone. Also having no dynamic RAM should help with this as well.

 

 

This is truly amaze balls in awesome sauce work Michael! A huge undertaking and wonderful that you 'blogged' it with us, for me the 'journey is better then the destination'. Thanks for sharing :)

Yogi

 

Thanks Yogi :) Yeah the likeness to a blog is what I was shooting for, glad to see that's how others perceived it as well. Like you, I really enjoy following threads like this showing something going from idea to reality. Perhaps that is also why I enjoy documentaries like the Nova series.

 

BTW isn't it totally awesome that this year we are seeing two Mini-ITX projects coming into reality (ÉclaireXL) :grin:

 

- Michael

Edited by mytekcontrols
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Maybe I missed it, but is our only option for a keyboard just a ps/2 one?

 

Would be kinda nice to use a more Atari like one.

 

Well you could always have something like this made...

 

wasd-a8-iso.png

www.wasdkeyboards.com

 

This is based on an ISO keyboard using relabeled key caps. Alternative key mapping in the TK-II firmware presently supports this (which is the basis for the PS2 keyboard in the 1088 XEL). For more info on this check out : TK-II Device Compatibility

 

But yeah only PS2 keyboards are going to be supported. Other options would be to create a Pokey piggyback that incorporated the 4051 mux chips on board to scan the original keyboard matrix.

 

Keep in mind that this new motherboard is targeted at use in a Mini-ITX case where the stock keyboard really wouldn't make a lot of sense anyway.

 

- Michael

Edited by mytekcontrols
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