@Doug
DECwriters real PDP8 machines? I never looked into these, but didn't you mean the DECmate here?
@Tom
I have thought about making a M8650 TTL clone, but in the end I have never started with it. I have managed to find some defective boards just by asking people on the forum and fixed them. Now I even have a spare one. Somehow I think these boards are highly overrated in price. Every PDP8 had at least one or more serial boards in it. But most people just don't want to sell their DEC spares. Spares are often used to swap for another spare.
When you are new in this DEC world, everything seems to be expensive and impossible to find. And if something even smells like DEC some people see the $$ signs in their eyes... When you are in a hurry to find parts, you will pay the price. When you are patient it might play out otherwise...
I remember that I wanted to buy a M847 diode board. Every time I missed the board on Ebay. And every time the next board on Ebay ended about 50 dollar higher in price because the others missed out on the board as well... Then I realised these boards were also very limited with just one bootstrap. So I designed the M847 extended edition... When that got popular the original M847 prices on Ebay got crushed... Now I have two of these original M847 diode boards in my box of spares, but I never even tested them.
I've also kicked out the M849 shield boards because after a while my machines were full of boards. These machines run fine without them, but once I was looking for such a board because I was missing one of these. So things can change over time...
Philipp Hachtmann wanted to do another run of his omni USB boards a few years back. I was interested back then but I never heard anything about these boards again. Since I found real boards I didn't really care about that Omni USB board any more. And to be honest, I didn't like the USB only construction. When I would clone a board I would like to see that it can be used for the original purpose as well... But everyone has his own design goals... I think Philipp's board can be very useful for Doug's project.
The serial disks is really a brilliant tool to start with your PDP8 experience... It is a bit slow trough a standard serial board. But who cares? It helped me to get my first Omnibus PDP8/e machine to become alive. Now I use two cloned floppy controllers for Don's RX02 emulator and a real drive. (So I have RXA0... RXA3) The RX02 emulator is really blazing fast. And I can use the serial disk on the 2nd serial board as data drives. So the speed is not really important for me in this case.
I'm really glad I don't have an 8/i. That would make things a bit more complicated to expand such a machine. So Doug's idea is brilliant to use one serial port for serial disk and the terminal. For my 8/L I have some idea's for a second serial port and a memory expansion. Mostly drawn already, but if doug has succes with his tool, I might remove the 2nd serial port... I was also working on 32K for the 8/L but that takes up a bit (...) more electronics, and you can't access that higher memory part from the front panel. But who cares if your OS can work with it...
Oh well... If one just could buy a container fully loaded with spare time...