There are several directions to take this.
- An exact replacement for the M8340 and M8341 using the original components. An exact copy of the last revision.
- A replacement for the M8340 and M8341 interchangeable with factory versions using available thru hole TTL parts.
- A replacement for the M8340 and M8341 interchangeable with factory versions using CPLD's.
- A single card combining the M8340 and M8341 functionality. This should be doable with either surface mount TTL, CPLD's, or an FPGA and level shifters/bus drivers.
- A single card that replaces the M8330 in slot 1, M8340 in slot 2, M8341 in slot 3, M8310 in slot 4, and M8300 in slot 5. This will no doubt require an FPGA to attain sufficient logic density. The M8320 (bus termination) would still need to be a separate card at the other end of the omnibus.
#1 is hands down the easiest to accomplish but it really doesn't get you to your goal because , finding the parts to populate the cards, while not impossible is going to be very difficult.
#2 seems like it would be a good choice for a new project. It keeps the changes to the design compartmented to individual IC's. I suspect that
parts availability is only going to continue to decline which will make this the same as #1 in a few years.
#3 is probably the closest to done. Vince has already made hardware. He needs to find time and motivation to finish and debug it.
#4 would be my personal choice to add an EAE to an existing system. I believe this would cost the least to manufacture but also be the most work.
#5 is a project I discussed with Warren Stearns a couple of years before his passing. I wanted to also have the memory, console port, and RF01 or DF32 on this board as well. It is a multi year project all by itself and I came to realize that I probably would not be able to keep motivated to complete it. The chance of this one ever happening seems to be nearly zero.
I am sure others have thought of this as well but Warren and I did come up with an idea that makes fixing DEC boards and #1 more practical. And that is to make replacement IC's using a surface mount board with the outline of the IC it is replacing and substituting available logic to associated pins. This isolates the problem to something that can be dealt with in a couple of evenings. And when the parts used go away you can just redesign that one piece rather than have to redo a whole quad board. FPGA's have a much shorter life than old TTL. I only half joke about the FPGA of the month club.
I have two sets of EAE boards. I am pretty sure neither of them is functional. Too many hobbies and not enough time in retirement.