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SiriusHardware 31st Jul 2021 8:03 pm

Re: Ortonview PCB
 
Ref: #139 - or just put a .OR 0x200 statement at the start, assemble it and use the uploader to load it directly into screen memory.

Slothie 31st Jul 2021 8:37 pm

Re: Ortonview PCB
 
Quote:

Originally Posted by SiriusHardware (Post 1394440)
Quote:

Once again the vital trace that needs cutting is on the top and runs near the DIP sockets!!
Can you cut the cross spars on the relevant socket out leaving only the two sides of the sockets left in the board? That will give you some leeway to see where you need to be.

Yes, I could probably do something like that. I think it also goes over to the other side of the board for a short bit so I might be able to scrape it there if its not too close to something else.

Slothie 31st Jul 2021 8:51 pm

Re: Ortonview PCB
 
1 Attachment(s)
Well that works well. It does make me look like I've got a handlebar moustache though :) But its a good proof of concept. I'll do a quick guide to what I did tomorrow.

SiriusHardware 31st Jul 2021 9:12 pm

Re: Ortonview PCB
 
1 Attachment(s)
Yes, I thought you were sporting a bit of a Wilf Lunn there. ;)

It goes to illustrate the point that if you're trying to represent something as detailed and individual as a face in so few pixels you have to get in quite a bit closer. Now we just have to go looking for as many suitable SOC / Sinclair related images as we can find. It's a shame we don't have a nice one of Karen.

The python 3 code I used to rip the image from the .BMP is even cruder than I remembered - it doesn't even output the .ASM code to a file, it just outputs it to the terminal window in the IDLE IDE and from there I cut and pasted it into Notepad and saved it with a .asm extension. Here it is, I know your python skills are much more polished so feel free to use as-is or improve. As written, it only works on 1-bit 64 * 64 pixel .BMP files.

Timbucus 31st Jul 2021 9:47 pm

Re: Ortonview PCB
 
To my great concern I was going to ask her daughter again for the photos but I just looked and when work swapped my phone all my contacts were lost so I no longer have her phone number - that is so sad.

SiriusHardware 31st Jul 2021 9:53 pm

Re: Ortonview PCB
 
I've thought a little more thought about it, Karen always struck me as a very private person who preferred to let her projects be her interface to the world - so she might have been rather horror stricken at the thought of her image being put 'out there', no matter how grainy or low-resolution.

Timbucus 31st Jul 2021 10:06 pm

Re: Ortonview PCB
 
That was my original assumption which is why I shied away from it in the Video I did but, I had discussed it with Emma just never chased it up in our conversations which obviously had other more important topics.

So on that note I will take some close ups that would work of the Mk14 related devices - we can do a slide show of those.

Mark1960 31st Jul 2021 10:40 pm

Re: Ortonview PCB
 
Another option for the ram instead of adding buffers might be to switch the ground connection to the ram using a diode from the battery and an npn transistor for 5v ground. With 5v switched off all inputs to the ram are pulled high.

SiriusHardware 2nd Aug 2021 5:18 pm

Re: Ortonview PCB
 
I'm about 80% of the way through the Ortonview build now - like Tim I don't seem to have any of the required skeleton phono sockets but I can just use the socket-on-a-bit-of coax which I used with the original lash-up until I get one.

Main jobs left are to add the timing mod for the 74LS365 buffers (I did have the foresight to make the necessary discrete track cuts before I fitted the buffer sockets) and to strap whatever needs to be strapped to make the 6116 work, ignoring the battery backup setup for the time being. One thing I don't have which I thought I did are 220pF capacitors, so I have some of those on the way. I either need four to run the board with the 'primitive' fix or one to use on the buffer timing mod, so either way, I am stalled until they arrive.

Following Slothie's observation that OrtonView + Memory adds very little to the supply current drawn from +5V I have for now just linked the incoming +5V from the MK14 to what would be the output terminal of the regulator if it was fitted. I've fitted as many 0.1uF supply decoupling capacitors as I can see holes for.

The additional reg could still come into its own when we start running other bits of hardware, so it is good that there is already a place for it on the PCB.

Slothie 2nd Aug 2021 5:51 pm

Re: Ortonview PCB
 
Its worth pointing out that many of the headers on the board are optional, the only ones you are likely to use the "options" ones and perhaps the I/O pins near the edge connector if you are going to drive the options from IO pins. And the 'noise' pins in the unlikely event you are going to build that part.

SiriusHardware 2nd Aug 2021 6:03 pm

Re: Ortonview PCB
 
It strikes me that a more realistic first 'Killer App' for the MK14 + VDU would be a clone of 'Pong', entirely in graphics mode with the score rendered as pixel digits. The noise generator would be useful for randomizing the insertion point and initial angle of travel of the 'ball'.

We just need to get the basic VDU stuff working absolutely flawlessly first, then we can start to have some fun. I doubt we'll ever get ELITE running on the MK14, but we should be able to come up with something vaguely amusing.

SiriusHardware 3rd Aug 2021 4:37 pm

Re: Ortonview PCB
 
A circuit query regarding the circuit as given in the project document - I notice the NWDS pullup resistor (R3) is 10K - when Tim and I were looking around for ways and means to observe and cure the corruption problem, one thing we did find was that raising the value of the NWDS pullup to 10K made the corruption problem happen more 'reliably', in order to observe it more easily.

If you (Slothie) are still getting occasional flickers in the display cell one step to the left of the data field (so, third one in from the right) even with the four capacitors fitted on A8-A11, try taking that resistor down to 4K7, which is actually the recommended value for the NWDS pullup in the original VDU docs anyway, and the value I had fitted all the time I was playing with my original lash-up version of OrtonView.

220pF capacitors still have not arrived yet, alas. To disable the battery-back feature and just use my 6116 as 'normal' RAM I take it I can either fit a schottky diode (which I happen not to have) in D2 or just link out D2 for now, link pins 2 and 3 of the write protect switch and don't fit the battery or D1. Did I miss anything?

Timbucus 3rd Aug 2021 4:39 pm

Re: Ortonview PCB
 
Just going through the bits that arrived today to see if I can build mine yet - I only have a standard 6116 as well.

SiriusHardware 3rd Aug 2021 4:45 pm

Re: Ortonview PCB
 
My 6116 is an ...LP, but I think Slothie has found the RAM retention feature does not work as he hoped, so he was looking at redesigning that, until we distracted him with talk of QWERTY keyboards.

Once I have the 220pF caps the only thing I will be short of is the correct Phono socket but I have a leaded one which I can use in the meantime.

Am I right about the NWDS pullup resistor? You tended to have yours at 10K, only with the actual intention of causing trouble?

Slothie 3rd Aug 2021 4:51 pm

Re: Ortonview PCB
 
Quote:

Originally Posted by SiriusHardware (Post 1395220)
220pF capacitors still have not arrived yet, alas. To disable the battery-back feature and just use my 6116 as 'normal' RAM I take it I can either fit a schottky diode (which I happen not to have) in D2 or just link out D2 for now, link pins 2 and 3 of the write protect switch and don't fit the battery or D1. Did I miss anything?

No thats about it,

As for the NWDS, when the write protect switch is closed there are 2 10k resistors (R1, R3) in parallel pulling up NWDS, making 5k. I didnt want to make that any lower.

SiriusHardware 3rd Aug 2021 4:54 pm

Re: Ortonview PCB
 
Ah, right. Changing the value of that pullup resistance may have unintended consequences, as observed earlier. The value seems important, or to be more precise, based on earlier observation, it ideally needs to be no more than 4K7.

If you remember, the capacitors appear to fix some sort of timing relationship between the rate of change of the states of A8-A11 and NWDS but raising the value of the pullup resistor (thereby slowing the rate of change of NWDS) actually cancels out some of the effect of the capacitors.

Timbucus 3rd Aug 2021 5:10 pm

Re: Ortonview PCB
 
Mine is 4.7K with a changeover switch to 10K to make the problem appear - my caps are only 47pF on mine (I cant remember if the 10K makes it appear with the the 47pF I will try again) but, I have some 220pF arrived today so will build this board with them - only four are needed right? Links on the others?

I am also not clear what other track to cut before soldering the sockets on - I have the first diagram but, maybe missed something in the later discussion on the battery etc.

Slothie 3rd Aug 2021 5:16 pm

Re: Ortonview PCB
 
Quote:

Originally Posted by SiriusHardware (Post 1395228)
Ah, right. Changing the value of that pullup resistance may have unintended consequences, as observed earlier. The value seems important, or to be more precise, based on earlier observation, it ideally needs to be no more than 4K7.

If you remember, the capacitors appear to fix some sort of timing relationship between the rate of change of the states of A8-A11 and NWDS but raising the value of the pullup resistor (thereby slowing the rate of change of NWDS) actually cancels out some of the effect of the capacitors.

Well there's no reason not to change R3 to 4.7k, so that the pullup is always at least 4.7k. With the WE switch closed it will only go down to about 3.2k which isn't going to cause a problem. I will change the schematic appropriately.

SiriusHardware 3rd Aug 2021 5:17 pm

Re: Ortonview PCB
 
Quote:

only four are needed right? Links on the others?
NO links on the others, unless you have a reason to want to short A0-A7 to 0V. Just fit the ones on A8-A11 and only if you are NOT intending to try the buffers as it's either / or. (Buffers + mod to the buffer enable circuit, OR direct connection without buffers and 4 x capacitors on A8-A11)

If you are not going to use the buffers you need to link across each of the 6 gates in each buffer to connect the system address bus directly to the PIC pins as they were in the original prototypes. If you have fitted turned pin sockets for the buffers you can just plug little hoops of solid core wire into the sockets.

SiriusHardware 3rd Aug 2021 5:20 pm

Re: Ortonview PCB
 
Tim, I thought I remembered you having raised your caps to a higher value than that - you don't have others fitted in parallel with the 47pFs, maybe on the other side of the PCB?


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