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-   -   Ortonview PCB (https://www.vintage-radio.net/forum/showthread.php?t=181460)

Slothie 8th Jul 2021 10:59 am

Re: Ortonview PCB
 
This is starting to sound like a "V2" thing... You could free up pins on the PIC by using a multiplexer or shift register to sample the option pins during retrace. It does rather damage the "single chip" concept though (not that its at important!)
The vertical bar thing will be important in the long run, it appears Tim has avoided it by adjusting the overscan on the TV, but an LCD TV might not have this luxury. For now I'm content just to pretend its not there for the time being until we can sort out the firmware. Until then we'll supply Sirius with a strip of black paper and some sellotape!

SiriusHardware 8th Jul 2021 11:26 am

Re: Ortonview PCB
 
Quote:

It does rather damage the "single chip" concept
I think that was quite a big deal, almost a non-negotiable point of honour for Karen, to be able to make her beloved PICs do so much that virtually nothing else was required. The buffers are an unfortunate after-necessity (possibly, I know you still harbour hopes that the problem can be coded around) because not even Karen could have anticipated the problem of the PIC port pins 'leaning' on the high address bits when in input mode - I think the buffers are an acceptable after-modification to this project because they are exactly how the SOC VDU handled its connection to / disconnection from the address bus. If the PIC pins could just be put into 'tristate' (high impedance) state that would be the first thing to try in firmware, but I don't think they can.

The 'dirty fix' (200pF capacitors from A8-A11 to 0V) works perfectly for me and has no known side effects, and actually Karen did have form there, early on she suggested 'slugging' (her term) some of the signal lines with capacitors to see if they solved issues and she may well have preferred that minimalist cure rather than using extra ICs to solve the problem more elegantly / correctly.

Same with the bright line blanking, if we can find a pin which can be used in output mode, you can probably just add a couple of resistors and a transistor to do the video line clamping during the 'bright line' period.

Regarding the 'hardware' solution to the problem, why use two items when you can do it with one? Black electrician's tape....

Timbucus 9th Jul 2021 12:17 am

Re: Ortonview PCB
 
Indeed I think she would have been impressed with this as well https://hackaday.com/2021/07/08/c64-demo-no-c64 no bright white line on the left of that!

Slothie 9th Jul 2021 9:04 am

Re: Ortonview PCB
 
So are you saying we should just forgo the PIC and connect the video to the SC/MPs F0 & F1?

Slothie 9th Jul 2021 12:05 pm

Re: Ortonview PCB
 
1 Attachment(s)
Well I've done some tidying up and played with FreeCAD to make some models for the missing components and a a pic of the (hopefully) final board. The models are a bit Dire Straits "Money for Nothing"-esque but I'm no Leonardo with CAD and FreeCAD is a bit quirky....

Here's a link to the non-mangled-by-the-forum version -> https://photos.app.goo.gl/an2Yk6deezBT6gc59

Timbucus 9th Jul 2021 4:23 pm

Re: Ortonview PCB
 
Quote:

Originally Posted by Slothie (Post 1388686)
So are you saying we should just forgo the PIC and connect the video to the SC/MPs F0 & F1?

Well I did wonder if overclocked as we have been informed it can be, if it could be made to display something... Cool project idea

Mark1960 9th Jul 2021 5:38 pm

Re: Ortonview PCB
 
I was looking at that possibility but I think the 8060 is too slow even at 8MHz. Each microcycle is 1us at 4MHz. Fastest instruction is 5 microcycles, so that would be 5us per pixel at 4MHz or 2.5us at 8MHz.

It might just be possible to drive an external character generator, similar to zx80, drive nop to the 8060 while the data goes to the character generator, but would still be very large pixels, maybe 16 characters by 8 lines.

Slothie 9th Jul 2021 7:39 pm

Re: Ortonview PCB
 
Well, I've done it. 5 PCBs on the way to try out!

Timbucus 9th Jul 2021 8:15 pm

Re: Ortonview PCB
 
Nice - I shall look forward to your first photo of it working...

SiriusHardware 10th Jul 2021 10:40 pm

Re: Ortonview PCB
 
Obviously, we will want to help to offset the cost of the five test PCBs so please let us know details via PM.

Timbucus 11th Jul 2021 11:59 am

Re: Ortonview PCB
 
Indeed happy to help with that and another test build if it helps.

Slothie 11th Jul 2021 12:10 pm

Re: Ortonview PCB
 
When I get them I will see if i can arrange to send some out, its going to be a couple of weeks because I cheaped out on the postage :) By them I will have decided how audacious I can be with the cost! That might also depend on if it actually works...

SiriusHardware 11th Jul 2021 10:19 pm

Re: Ortonview PCB
 
There are some parts I'm not familiar with, like the RAM and the skeleton video-out socket, so if you can put together a short list of the more exotic parts and suggested suppliers ie, where you got yours from, and drop it off to interested parties via PM we can start to gather any Slothie-version parts needed in advance.

Tim and I already have working OrtonViews, mine is certainly in need of rebuilding properly so the majority of parts needed will come from that original rough prototype. It would be interesting to hear if anyone else that we don't already know of has also built an Ortonview.

Mark1960 11th Jul 2021 11:33 pm

Re: Ortonview PCB
 
The ram looks to be 6116 pin compatible, but try and use the LP version if you plan to use battery backup.

Battery socket looks a common type but might be good to confirm the part used.

Could someone add a link to the best firmware version as a starting point? It would probably be good to have a reference from this thread anyway.

I might wire up an orton view on protoboard just to join in. Its probably not worth postage charges to canada.

Slothie 13th Jul 2021 9:05 am

Re: Ortonview PCB
 
The battery socket is Multicomp CH29-2032LF but there are others that are pin compatible available from other manufacturers, but the Multicomp seemed to be the cheapest. I've seen the SMD version of this on eBay, which could probably be pressed into service since the through hole pads are on both sides....

The Phono socket is just something I found on eBay, but appears to be the same as Cliff FC68391 - I've checked the footprint and it should fit. The critical dimension between the front ground pin and the rear (signal) pin is 6.35mm so other types may well fit.

The write protect switch is a CK 1101 [specifically 1101M2S3AV2BE2] But the critical dimension is the 4.7mm pin pitch. In retrospect the CK switch is pricey, and I might have been better off using one with a 0.1" pitch which seem to be all over eBay.

All the above are available from Farnell/Newark and other suppliers. I was going to link but I know that is frowned on but they all turn up if you search on site or google.

The RAM is 6116LP compatible, I just used the M5M5117 because I have 8 or so of them....

Slothie 13th Jul 2021 12:40 pm

Re: Ortonview PCB
 
I've just noticed that the 4.7mm spacing on the switch is the same on PCB mount sub-min toggle switches, so that's an option too.

Mark1960 14th Jul 2021 12:00 am

Re: Ortonview PCB
 
I was just scanning through the mk14 vdu thread again to review the development of the OrtonView. Gave myself a bit of a panic when I saw Karen was planning to use the pic16f887 rather than the pic16f877 before I saw that she changed back to the pic16f877. Then another when I read that she swapped the B and D ports, before I realised that I searched the thread backwards when I was looking for the schematic, so was already looking at the schematic after the port swap.

What I couldn’t find was why the NENIN output of the pic has a diode in series. Does anyone know why the diode is needed?

SiriusHardware 14th Jul 2021 7:13 am

Re: Ortonview PCB
 
I can't remember which way the diode 'points' but it is to convert the totem-pole NENIN drive output from the VDU to one which pulls (up?) only. When not driven high via the diode NENIN is held low via a resistor, or so I seem to remember.

The original SOC VDU has the same arrangement on the output of the gate which drives NENIN on the MK14, so I think the NENIN drive arrangement was just copied verbatim.

If you sift carefully through the original thread there are a couple of posts where this is mentioned.

Mark1960 14th Jul 2021 9:56 pm

Re: Ortonview PCB
 
I found that part of the mk14 vdu thread, and I even replied to it with my concern about the active pull up if ever NBUSRQ was connected to NENIN, which is what was also bothering me this time round.

I’m still not sure why the original mk14 vdu used a 470 ohm pull down and npn transistor to pull up on the output of a cmos 4011. Maybe they wanted to protect the 4011 from an incorrectly modified mk14, or thought it couldn’t drive the 8060 NENIN, which doesn’t seem to have the input current in the 8060 spec.

Slothie 22nd Jul 2021 1:31 pm

Re: Ortonview PCB
 
3 Attachment(s)
Hurrah! The Ortonview PCBs have arrived. They look nice, the quality of the silkscreen on the board is not as good as it usually is but not too bad. The footprint I made for the CR2032 is fine, the phono connector is a bit snug and I had to straighten the pins to get them into the board as shown in the picture, and I had to file the pins on the switch to get it in but not much, and it might just be the cheapo switch I got off eBay :D
I'll be putting it together to see if it works, and if so how well it works. After Sirius and possibly Tim have theirs there may be 2 or 3 spare and If people want to wait for that before registering an interest I'll understand, and I've still got to decide and tell you how much I want for them! I need to discuss logistics with Sirius anyway as he has volunteered to oversee distribution etc.

Bear in mind this is board intended to test various things and firmware updates, and should not be considered a final product in any way! That said I'll put together some notes on anything that occurs to me as I'm assembling it this afternoon and put them up here. I do intend to produce a more "final" board in the future, these are intended for people who want to help me shake out the bugs.


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