Read. The. Freakin'. Manual.

Those of you who know me will know that I am a bit of an idiot. Not as much as the young man who just rode past my house on a bike, on the wrong side of the road, busy looking at his phone. But a bit of an idiot nonetheless.

The PX-8 came with a massive amount of stuff and the donor had mentioned the documentation that he provided with it included the technical manual etc. I didn't remember seeing it but while I was tidying up the workspace (which does happen every now and again), I came across a non-descript folder that had an Epson printer manual tucked into the front cover. It was the documentation. Original documentation. An original Technical Manual. With A3 schematics and everything. Nice.

But most importantly, it contained this:

Is this the info I need??

YES! The Holy Grail!
UD80 I/O Port Pinout!

So, after looking at this innocent piece of paper I realised that my efforts to get the UD80 to work were never going to work, because I was connecting up the wrong wires (I was trying to use DTR and DSR). As mentioned above, I am an idiot.

There are five wires, and they are actually:

• Ground
• TxD
• RxD
• DTR (Handshake in)
• CTS (Handshake out)

More importantly, the pin numbers are specified at the UD80 side! 

A quick re-configure of the cables and....

Correctly wired up.

....no difference. I did see that if I try to send the B:WS.COM file to the UD80 I actually got 'R's instead of garbage. This is good though, as it is the FILINK program indicating it's waiting to send a file. Obviously, we're waiting to receive a file so the UD80 isn't listening.

Then I remembered the push button on the front. I pushed it. No difference. But was the switch actually working? To cut a long story short, it wasn't really. It had a resistance of over 50 ohms when the switch was pressed, which is probably not really what a push button switch is supposed to do. To get around this I soldered a couple of wires to the bottom of the original switch, fed them through the hole in the front and attached an Acorn Electron keyswitch (not a pristine one I should add).

A bit Heath-Robinson.
Electron keyswitch at the end of the
red and black wires.

After booting up the PX-8, connecting all the cables, switching the UD80 on and firing up FILINK I got... Nothing. 

Then I remembered and pushed the button. *DOH*  And, would you believe it, this is what I got:

WHAT??

It only bloody works!

I was so surprised it worked I hadn't made a note of exactly what I'd done. In my haste I also managed to download the WSX.COM file and copy it over the UD80-DRV.COM file. So I had to go back to the beginning and try again. 

To say this is finicky is putting it mildly. Everything has to be switched on in the right order, at the right time. I can successfully download the UD80 driver to A: but it tries to overwrite the UD80 driver with the WSX.COM file. If I stop it and try to give it another name I get 'ERROR' on the UD80 although it's probably because it's just sending it and doesn't expect me to get in the way trying to find the 'X' key... (Of course, it turns out that I don't need to enter a filename and, if I don't, then the files are received as they are named from the UD80 ROM. Doh.)

ERROR - Also out of focus...

Once the UD80 driver is run, there doesn't seem to be anything to do and the output of the screen is sent to the UD80. It's confusing at first because the PX-8 has a 'menu' system it runs by default and the UD80 sees this as graphics characters. Pressing 'Esc' switches out of that and brings the display on the UD80 back to a system prompt.

And from there, it looks just like any other early 80's PC like computer running CP/M. 

The PX-8 'CONFIG' program

WordStar but without the extension installed..

Basic operation - note garbage at the top from the 'Menu'
system on the PX-8

Running a DIR and STAT command from the command 
prompt. Looks almost like any early PC like computer.

Of course the first thing I did after recovering from the shock, was try the games. They don't work. Boo! The UD80 automatically switches to 40 column mode and instead of graphics characters there's a random selection of letters and block graphics. I didn't think that they would work properly but it was worth a go. :)

Things left to do:

1) Document exactly what I need to do to get this running properly. The big issue here is that there are no batteries in any of this kit, having been removed for preservation reasons. As a result a lot of what's needed to configure this setup would only have needed to have been done once back in the day, as the resulting config would be retained in the RAM/RAMDisk. Everytime I turn the PX-8 on it's like I'm turning on a brand new unit with no non-volatile storage. If I leave the mains charger plugged in then it keeps the settings and the driver file stays in memory but as soon as it is unplugged they are gone. But this is a minor inconvenience to ensure that this system does not die from battery vomit...

2) Get some proper photos of everything and organise the ROM dumps. There's a superb resource on the PX-8 here and the curator of that site might find this sort of stuff useful.

3) Try the output in a different telly*. That monitor screen and driver really does NOT seem like that composite signal.

4) Build an RGB cable. I wonder if it will work with SCART..?

So, finally, a success. And one that I'm really pleased with. Without the documentation from the previous owner this would probably have been sat in a box for another twenty years having never been used again. As the title says, you should always Read The Freakin' Manual!

*BREAKING NEWS

I tried the output in a different TV and the output is still not great, so it's just the way it comes out of the UD80. So, time to try an RGB cable...

Hmmm.