Pin. Pin. Pin. Pin.

Pinouts. Lots of pinouts. Or at least I thought I should properly document the pinouts of the UD-80. This will be the last post on this for a little while as I still have lots of other stuff to look at, including a TV with a faulty SCART input...

First up, SCART.

RGB Cable - 6-pin DIN to SCART

The socket is a 6 pin DIN (240 degrees) socket arranged in the following order:

UD80   Pin            Pin  SCART

GND    1: ---------- : 18  GND

CSYNC  2: ---------- : 20  SYNC (via 470R resistor & 10uf cap)

RED    3: ---------- : 15  RED

GREEN  4: ---------- : 11  GREEN

BLUE   5: ---------- : 7   BLUE

+5V    6: ---------- : 16  RGB BLANKING

Diagram below:

What a lovely diagram.

One key thing here is that I'm not convinced I've got the RGB in the right order. But I would point out that the PX-8 and UD-80 are monochrome, so what difference does it make? :) At least I'm fairly sure that GREEN is in the right place at least...

The CSYNC signal was measuring 5v which is TTL level and a bit over the top for the SCART standard. Sticking the resistor in there, when it's connected to the 75 ohm impedance TV connector, means the output is a much more standard 520mV (thanks to the video by Voultar where he describes the issues with old equipment - see here for that video). The capacitor de-couples any DC bias in the signal.

Here's one I made earlier:

GAAAH!!

And here's one where I put the SCART plug screw on before I re-soldered the plug back on:

Remembered this time...

And, of course, I must not forget the patented DIN plug 'Maximum Assistance Super Hold' (MASH) device i.e. a potatoe:

Hmmmm. Potatoes....

One of the best things to hold the DIN plug so the pins stay in place and don't fall out while you're trying to solder the plug. An excellent tip there. As you can see I did the 8 pin and the 6 pin DIN plugs for the UD-80 with this particular MASH.

Does it work? Of course.

WordStar. You youngsters don't know you're
born. 

A whole 2k free on the A: drive!

Rather interestingly, there is some slight distortion towards the bottom of the screen that looked similar to the composite interference. I suspect this may be related to the UD-80 rather than any issue with my cable but I might investigate at some point.

Next up, the UD-80 connection itself.

UD-80 Serial Cable - 8-pin DIN to 8-pin Mini-DIN

The socket on the front of the UD-80 is an 8-pin 270 degree DIN socket. It can accommodate a 5-pin 180 degree plug since only pins 1 to 5 are actually used. The pins are arranged as follows:

    UD80  Pin            Pin  PX-8 RS232

  GROUND  2: ---------- : 1   GROUND

 DATA IN  1: ---------- : 2   DATA OUT

DATA OUT  3: ---------- : 3   DATA IN

     CTS  5: ---------- : 4   DTR

     DTR  4: ---------- : 5   CTS

     N/C  6:            : 6   N/C

     N/C  7:            : 7   N/C

     N/C  8:            : 8   N/C

The PX-8 can, apparently, use either the RS232 or Serial ports with the UD-80. Everything I have done so far has been with the RS232 port.

UD-80 Operation

The UD-80 replicates and extends the display of the PX-8 from an 8 line LCD display to an 80 or 40 column display with 24 lines via a composite or RGB output (see above for info on RGB). The UD-80 comes with a built-in extension for WordStar to allow the use of the additional screen real-estate. Other applications need to be specifically modified to make use of the additional screen space so they are likely to be few and far between.

This brief 'start-up' guide is based on an PX-8 with no batteries installed and, as such, a lot of the steps taken here would, in the day, only have been required once, particularly if the RAMDisk was fitted (I have one but it's broken. :( ).

Step 1 - Plug in the UD-80 to PX-8 interface cable.

Step 2 - Plug in either composite or RGB monitor according to taste.

Step 3 - Switch on the PX-8 which should default to the start menu.

Step 4 - Switch on the UD-80 which should display a UD-80 banner at the top of the monitor screen.

Step 5 - Run CONFIG.COM and configure 3 blocks of User BIOS space (run the program, select 'B' then press '3' and enter, then ESC twice to get back to the menu).

Step 6 - From the menu or from the CP/M prompt run FILINK.COM

Step 7 - Press 'R' to receive files and then 'Enter' when prompted for a filename.

Step 8 - Press the button on the front of the UD-80. A 'Transmitting...' message should appear and FILINK should indicate it is receiving UD80-DRV.COM and the WSX.COM.

Step 9 - When the downloads in FILINK have completed quit back to the menu and run the UD80-DRV.COM file that will be shown in the A: drive.

Step 10 - Switch the UD-80 off then on again to reset to 'normal' mode. A message should appear indicating that the driver is resident and can be cleared by a 'Reset'.

At this point anything that is typed on the PX-8 will appear on the monitor connected to the UD-80. In the event that the PX-8 manages to get back to it's default menu just press 'Esc' to return to the CP/M prompt and the UD-80 will spring back into life. Note that some 'garbage' appears at the top of the screen when the PX-8 returns to the menu with the UD-80 driver active.

Note garbage at the top from the PX-8 menu

During the use of this device I did have some situations where the UD-80 and PX-8 got out of step. A quick switch off and back on of the UD-80 normally resolved things (the more things change, the more they stay the same...).

So, there you go. A slightly dull but informative post for anyone with an Oval Automation UD-80 serial display adaptor for the Epson PX-8. I promise I'll stop going on about it now.

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.