new 6x0x board project

[note: this went out to the N8VEM mailing list. The proposed 6x0x schematic and PCB layout files are at http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=ECB%206x0x ] Hi! Sorry for the long message. I have a lot to say about a new N8VEM board project and am asking for your help. I think the 6x0x host processor, 6x0x IO mezzanine, and 6x0x ECB backplane are in need of a redesign and PCB respin. The three board "sandwich" approach has some major limitations and has led to some really weird and unnecessary complications. All the 6x0x PCBs are out so this is a great time to rethink the whole approach. Some builders and I have been discussing the topic and it dovetails nicely with some other improvements builders have been asking about. For example, it would be nice if we had a form factor that leveraged more easily stock ATX cases and power supplies. Also the ability to use 6U chassis with Eurocard backplanes (aka VME) form factor would help. Attached are notional redesign of the 6x0x board series into a single integrated board. It is still an ECB board but as a bus controller rather than as a peripheral like the 6x0x host processor. The new 6x0x board includes the dual CPU socket for 6502, 6809, and 6802 compatibility as well as all the IO from the 6x0x IO mezzanine (serial, parallel GPIO, timers, etc). As it is no longer a peripheral on the ECB bus it now includes a variant of the ParPropPort built in to provide full builder interface such as VGA display, PS/2 keyboard, SD mass storage, speaker, etc for complete standalone capability. Please review the proposed 6x0x schematic and PCB layout files and send me any changes and/or corrections. The new board is ATX and 6U chassis compatible. You can mount it in a stock ATX case and use a stock ATX power supply unmodified. Likewise with a 6U chassis. I am very interested in any discussion points on the 6x0x however please keep in mind this is an incremental step to addressing broader issues with the N8VEM collection of boards. You can still keep it out of a case altogether and set it on your workbench if you like or mount on some plywood. Assuming the new 6x0x form factor design is successful, I would like to adopt this form factor for other N8VEM boards to provide better and more functionally complete peripherals. Probably the next step would be to redesign the N8 to use the new form factor although it still remains to be seen if and how this works. We already have a notional schematic and PCB layout so the next step is to get some prototype boards. I will get four (4) prototype PCBs from Advanced Circuits as soon as the PCB completes some initial trace route optimization. Please keep in mind though the initial prototype boards will almost certainly not work as intended and will require extensive debugging, cuts and jumpers, dead-bugs, and all sorts of heinous, grisly PCB circuit modifications. As a result the initial build and test team has to be small and limited to the most experienced builders. If you recall the N8 and uPD 7220 GDC build and test phases then you'll know what I am referring too! If you have any questions or comments please feel free to ask. Thanks and have a nice day! Andrew Lynch