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NobodyIsHere
July 19th, 2008, 02:36 PM
Hi All,
The N8VEM SBC project seems to be going well. I sold the whole first batch of PCBs and another batch is on its way!

With the SBC working, now I am concentrating on making the ECB backplane working. I have a draft design and am asking for comments and suggestions from any experienced PCB designers, engineers, or people familiar with the ECB.

If you'd like to help, I posted a PDF with the PCB layout and traces at the N8VEM Google Group website.

http://groups.google.com/group/n8vem/files?&sort=rdate

Thanks!

Andrew Lynch

NobodyIsHere
July 30th, 2008, 03:42 AM
Hi!
I did get some help on reviewing the N8VEM ECB backplane PCB.

After I was satisfied with the design, I place the manufacturing order. Due to the special nature of these PCBs, I am only ordering a few. If they turn out to be more popular than I am expecting, I can reorder more when I run out.

The ECB backplane is designed to be completely generic ECB implementation and supports a lot of features not used by the N8VEM SBC.

I am expecting delivery of the ECB backplane PCBs in mid August sometime and will process any orders at that time. Sorry, as before no pre-paid or advance orders.

In the meantime, I am working on an ECB bus monitor project. I am in the schematic and PCB layout portion right now. It will be a while before the routing can begin as this is a fairly complex project. You can see the original design here (caution 28MB download):

http://www.hd64180-ecb.de/assets/download2008/ct_bus_monitor.pdf

The version I am making will have some modifications. It will include LED status lights for all the Address, Data, and Control bus signals. It will use regular DIP switches rather than the Hex input switches and some other minor changes due to parts obsolescence.

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
August 5th, 2008, 04:05 AM
Hi!
The N8VEM ECB backplane PCBs have not arrived yet but I have made some progress on the ECB bus monitor project.

I completed the schematic capture of the ECB bus monitor based on the design in the article. In addition, I added address and control bus status indicator LEDs. Some parts had to be replaced in the design due to obsolescence such as the 74LS01 (quad NAND gate OC), ULN 2003/ULN 2004 (inverters, high power) and a AA119 Germanium Diode.

The PCB has been laid out and is in the auto router at the moment. However, as with any design I would much appreciate some peer review of the schematic to catch any errors/misinterpretations *before* this goes to PCB manufacturing. If you have some electronics experience and are willing to help out this all volunteer amateur home brew computer project, please take a look at this schematic:

http://groups.google.com/group/n8vem/files?&sort=date

The file name is "Printing BusMonitor-sch.pdf" You can compare it against the original published design in the C'T Projekt magazine (German text) at the URL earlier in this thread.

I am happy to answer any questions you may have on the subject. Note: I have *not* built a prototype of the original ECB bus monitor so please don't take the original article as absolute truth. It may contain logic flaws as well.

Thanks in advance for any help!

Andrew Lynch

PS, there have been a few more successful N8VEM SBC builds recently. Last night a builder posted a very nice photo of their completed and working system. It is very nice looking and impressive photography. They did an excellent job. If I were advertising, I'd consider using that photo!

NobodyIsHere
August 13th, 2008, 05:18 PM
Hi!
The N8EM ECB backplane PCBs have arrived. If you are interested in buying one ($20 plus shipping) or an N8VEM SBC PCB, please contact me by email or PM.

Thanks!

Andrew Lynch

http://groups.google.com/group/n8vem