Re: Ortonview PCB
 

Yes, dont fit load capacitors where not needed, leave the locations empty if not required. I only put in 12 in case I needed to experiment with them, because it was easier to put them all in than ask if they might be useful.

At the moment the buffer option isn't working, there is an idea to see if we can fix it (see the image in this post) but as yet it is untested.

Re: Ortonview PCB
 

I've already done the buffer enable mod (minus one needed capacitor) so I will be trying the buffers option first.

Re: Ortonview PCB
 

I'm trying a different type of Phono (video out) socket. You can find them by searching on this part number.

TruConnect LP-0841-3Y-05A

No idea if they are a good fit for the pinout in Slothie's OV PCB, I just like the idea of having the socket colour coded yellow (for video).

Re: Ortonview PCB
 

Groan, it's back to front isn't it? The single 'foot' needs to be at the back. Back to the internet...

Re: Ortonview PCB
 

From the look of the data sheet it will fit into the holes, but the pinout is different. However the tracks can be cut and re-connected with wire links easily.

Re: Ortonview PCB
 

The "foot" at the front is GND on both the PCB and the connector, the left and right connections are GND on the PCB and signal connections on the connector. You could cut the traces connecting the gnd to the pins and re-route things.
If you're buying from Rapid then the "RVFM Black PCB Skeleton Phono Skt" and the red one will fit. If from Farnell or someone else then the Cliff FC68391 works.

I got mine from eBay, and naturally I looked just now and they are nowhere to be seen and its full of the truconnect style! Looks like I made a poor choice (again),

Re: Ortonview PCB
 

On your Cliff type socket it looks to me as though the centre contact pin is set furthest away from the plug entry hole, whereas on the one I described in #163 I think the centre contact pin is offset towards the plug entry hole. I'll see when it gets here.

I see Farnell etc appear to have your original recommended Cliff part, so I may have to get it from there. In the meantime I have an inline socket dangling on the end of a short bit of slim RF Coax - I can use that.

Edit: Thanks for the further info. Main mistake I made was deciding to order a connector when I do not have the PCB to hand - it is at work at the moment.

Re: Ortonview PCB
 

Yes, on the socket I used the pin furthest from the hole is the signal and the other 3 are ground. The trueconnect one has ground nearest the hole but the other 2 are connected to the signal, one switched the other unswitched. It has no "rear" pin.

Re: Ortonview PCB
 

I did for testing purposes but, when I finally fitted them to the top I dropped back to the lowest value that worked on the basis of simplicity.

Re: Ortonview PCB
 

I can send you one if you want -the minimum order was 10 from Farnell of the cliff non colour coded ones!

Re: Ortonview PCB
 

Hmm, that's a huge diffference from the value (150pF or greater) that I had to use to get to the same point. The optimum value of the capacitors could also vary depending on what else is on the A8-A11 lines. This is why I want to get away from the capacitor bodge if possible, to arrive at something which works for every one, every time.

I thought of another interesting issue as well, specifically relating to Mark. He's in a 60Hz country and the original SOC VDU and Ortonview are both designed to produce a 50Hz framerate. My Philips CM8524 monitor will run at 60Hz although the picture flattens a bit, but I think the ability to tolerate the difference will vary from display to display.

Modern flatscreens will probably cope with it quite well as they essentially rescale whatever they detect to fit on their screen. I imagine most will cope with 50Hz or 60Hz equally well.

One thing Mark could try is to find a crystal (or signal generator) with a frequency of around ((16/5) x 6) MHz = 19.2Mhz, which I think would produce a framerate of around 60Hz. Luckily 19.2MHz is comfortably inside the 20MHz maximum clock frequency of the 877 and it seems to be a commonly available off the peg crystal.

Who knows what issues this might raise, though. This is just one more reason why we need Mark involved in this phase of testing.

Re: Ortonview PCB
 

Oh, yes please.. you have a PM.

Re: Ortonview PCB
 

One problem Mark may find is that the US 60Hz standard only has 525 lines per frame rather than the 625 of the 50Hz standard. It might be possible to tweak the firmware to allow for this however. I'm not sure how it affects the line time either. But it would be unfair if Mark didn't have any challenges to deal with!

Re: Ortonview PCB
 

I think virtually all modern screens will have firmware and chipsets which travel all around the world and are equally happy with the 50Hz / 625 line and 525 line / 60Hz standard, and a lot of the late generation CRT TVs and monitors probably do too.

At least the VDUs (SOC and Ortonview) are mono-only so PAL vs. NTSC is one thing we won't have to worry about.

Re: Ortonview PCB
 

I brought a small Samsung lcd tv to Canada from the Uk, as it runs on 110 to 240v and supports both PAL and NTSC, as most uk tvs do. The advantage of a company paid move was I just brought everything, including boxes of magazines going back to the 60s.

Unfortunately Canadian TVs don’t work on PAL, so my old LG DVD player only worked in monochrome on the big TV even though I had the region unlock code, but it stopped working last year and I haven’t tried to get it working again yet. Suspect it might be bit rot, but could just be battery backup.

I use the small TV for experimenting with the TMS9x18 and was planning to try with the 29 version at some point. I’ll use it for the Ortonview but I can also try on an NTSC only TV later.

Re: Ortonview PCB
 

Briefly OT, does your DVD player have RGB-out and the TV have RGB-In? You can bypass any PAL / NTSC colour encoding problems that way.

Unfortunately I think 'Component' (YPBPR) video has always been more popular than RGB stateside and much less commonly available on European video equipment, so you could find that while the DVD player only has RGB-out the TV only has 'Component' in.

Re: Ortonview PCB
 

It has composite, s-video and scart. I’m not sure what features are supported, I think I tried RGB, but not sure now if that was with UK or Canadian TV, I think I blamed the SCART cable I picked up cheap in a pound shop one time I was visiting the UK. Maybe it was RGB to Component issue. It doesn’t power up correctly anymore, after about 30 second delay with blank display from the standby light changing from red to green the display shows all segments on. Its an LG DVD-3200E, if anyone has any idea what the fault could be.

Re: Ortonview PCB
 

Probably one for the 'Modern Technology' section, that's where the people who still work on current and recent tech mostly hang out. A very helpful bunch.

'Component' normally uses phono output and input connections colour coded Red, Green, Blue (which is what you would expect RGB to use, but never mind) - as opposed to the Yellow / Red / White of "AV" (Composite video +stereo sound).

That explains how your MK14 went along for the ride. I've lost count of the number of times I've heard that people lost or discarded them in house moves, so yours was extremely lucky to make it past that point.

Re: Ortonview PCB
 

I wouldn’t of parted with the MK14, though it had been stored in less than ideal conditions, a jiffy bag in a damp garage for about ten years, it survived in remarkably good condition. I did unfortunately get rid of a few things that I wish I had kept, including an old phillips MDCR that probably only really needed a belt, an old dot matrix printer that I couldn’t find print ribbon for and an old tektronix D10 scope.

Re: Ortonview PCB
 

I found some SMD 220pF capacitors, so I soldered one in place in the buffer enable delay mod and brought the board home. I decided to try it straight off, with buffers and extra RAM fitted. Unfortunately it doesn't look good on first try, there is a lot of noise on the displays between the address and data fields and the VDU itself is producing an abormal - height screen.

So I removed the PIC and the buffers leaving only the 6116 and 7402 address decoder in place, powered up to find a normal MK14 display and found that the memory by itself works fine, with any data entered over the range 0200-07FF 'sticking' as it should.

Next, I'll try powering the fully populated OrtonView from 5V-only - in those circumstances it should just display the random start-up content of the 6116 but should otherwise give me a normal 16 x 32 character VDU display output.