UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Computers

Notices

Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

Reply
 
Thread Tools
Old 19th Jun 2022, 10:12 am   #81
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

Well done coolsnaz22, you are putting the rest of us to shame here, quietly working away on new stuff for your MK14s. That's an amazingly compact build for a veroboard job. You mentioned that it can plug into your original backplane, can it be plugged in alongside the VDU, or is it only instead of? The extra RAM is just what the VDU always needed.

I would be interested to see your original VDU running some time because I have noticed that in graphics mode mine has very thin black vertical lines between every 8 pixels, like 'jail bars', which slightly spoil the appearance of any graphics rendered on it. Karen's 'Ortonview' hardware emulator of the VDU ironically does not emulate this 'feature' as it produces pixel-perfect output.

I did put together and test a little bit of hang-off hardware for my MK14 about a week ago, nothing as ambitious as yours, but I haven't had time to play with it properly yet.
SiriusHardware is online now   Reply With Quote
Old 22nd Jun 2022, 2:58 pm   #82
coolsnaz2
Triode
 
Join Date: Aug 2020
Location: Wallington, Greater London, UK.
Posts: 34
Default Re: Yet another MK14 tape interface (ESP32).

SiriusHardware

Find attached two photos showing VDU output, characters and graphics. I need to make some adjustments to the TV, top two rows not showing and picture is not central.

If I manage to adjust the TV, I will try and get some more meaningful text and graphics on the screen.

Currently backplane will only except one card, VDU or memory expansion card, I am looking at adding addition socket to backplane so that both can be plugged in.
Attached Thumbnails
Click image for larger version

Name:	20220622_153409.jpg
Views:	31
Size:	66.5 KB
ID:	259552   Click image for larger version

Name:	20220622_153435.jpg
Views:	34
Size:	56.8 KB
ID:	259553  
coolsnaz2 is offline   Reply With Quote
Old 22nd Jun 2022, 10:06 pm   #83
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

Thanks for the images, there is one area in your graphics image where there is enough white area in a vertical line that I think I see a thin black vertical line going down through that area, but it is complicated by the fact that the image also seems to have near vertical diagonal lines running through it as well, although those are probably moire patterning / camera artefacts and not real.

If you ever get the VDU and extra memory running in tandem, point the VDU at 0600-07FF (which I think is occupied by RAM in your setup) and fill that area with FF which will display a solid white square on the screen - it will be interesting to see if you get the same thin black vertical lines between each byte on the screen as I do.

Adjusting the height will be no problem but I find the image generated by the original SOC VDU is always a little bit off centre to the left, which you can only really compensate for if your display has a horizontal shift / horizontal position control.
SiriusHardware is online now   Reply With Quote
Old 24th Jun 2022, 3:00 pm   #84
coolsnaz2
Triode
 
Join Date: Aug 2020
Location: Wallington, Greater London, UK.
Posts: 34
Default Re: Yet another MK14 tape interface (ESP32).

SiriusHardware

Please find attached updated photos, which clearly show your 'jail bars'.

1st photo taken with phone, 2nd & 3rd taken with Canon EOS camera.

So the 'jail bars' are a feature of the original MK14 VDU board.
Attached Thumbnails
Click image for larger version

Name:	20220623_222233.jpg
Views:	30
Size:	33.4 KB
ID:	259731   Click image for larger version

Name:	IMG_1075.jpg
Views:	40
Size:	41.0 KB
ID:	259732   Click image for larger version

Name:	IMG_1076.jpg
Views:	32
Size:	43.0 KB
ID:	259733  
coolsnaz2 is offline   Reply With Quote
Old 24th Jun 2022, 8:59 pm   #85
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

Thanks for trying that as I don't know anyone else with a still working original VDU to try it out. Tim(bucus) has one of the Czech SOC VDU replicas, but still to be built as far as I know. It's a pity I don't really understand the SOC VDU circuit, maybe it would be possible to stretch the length of every eighth graphics pixel somehow - I think every eighth pixel being slightly wider would be less noticeable than that thin vertical black line.

As mentioned before Karen Orton's 'Ortonview' (PIC based Hardware emulator of the SOC VDU) ironically does not have this defect and produces beautiful sharp images with no gaps between bytes.
SiriusHardware is online now   Reply With Quote
Old 24th Jun 2022, 10:11 pm   #86
Mark1960
Heptode
 
Join Date: Mar 2020
Location: Kitchener, Ontario, Canada
Posts: 834
Default Re: Yet another MK14 tape interface (ESP32).

I haven’t looked at the vdu circuit recently but my guess is that black line is due to shifting a 0 into the shift register and a slight delay before the next byte is loaded. Maybe the shift register input could be connected to the least significant bit output from the shift register to shift in a 0 or 1 to match the last bit output.

It would be better if the delay between shifting the last bit and loading the next byte could be removed. I wonder if there is a setup time issue on the shift/load control of the shift register.

I’m guessing you wouldn’t want to wire mod your original vdu though.
Mark1960 is online now   Reply With Quote
Old 24th Jun 2022, 10:31 pm   #87
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

No, probably not. Luckily I have my Ortonview for perfect output. I guess the original SOC VDU is what it is, but my thanks to coolsnaz2 for confirming that it's not just an individual defect on mine.
SiriusHardware is online now   Reply With Quote
Old 25th Jun 2022, 6:23 pm   #88
Timbucus
Octode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 1,174
Default Re: Yet another MK14 tape interface (ESP32).

Quote:
Originally Posted by SiriusHardware View Post
Thanks for trying that as I don't know anyone else with a still working original VDU to try it out. Tim(bucus) has one of the Czech SOC VDU replicas, but still to be built as far as I know. It's a pity I don't really understand the SOC VDU circuit, maybe it would be possible to stretch the length of every eighth graphics pixel somehow - I think every eighth pixel being slightly wider would be less noticeable than that thin vertical black line.
I have my repro built and working - can't say I noticed the jailbars but, perhaps never run it with a full white background. I will dig it out and have a try.
Timbucus is offline   Reply With Quote
Old 26th Jun 2022, 10:33 pm   #89
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

I expect that it should have the same quirk, if not we will want to know the reason why.

It's funny that I don't remember this as a problem at all but then the MK14 and SOC VDU were the first such items that I had ever personally encountered so whatever they did was 'normal' in my eyes. It's only now, with the benefit of 40+ years of seeing other VDUs that I can see that problem.
SiriusHardware is online now   Reply With Quote
Old 30th Jun 2022, 11:55 am   #90
Timbucus
Octode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 1,174
Default Re: Yet another MK14 tape interface (ESP32).

Tried to capture a picture of an all white MK14 screen using my Replica SOC VDU on my LCD in the workshop it is pretty poor so used the CRT in the Study. This is taken in manual mode on my Camera - as you can see there are faint lines that correspond to the jailbar position but, the blurring makes them almost unnoticeable.

Click image for larger version

Name:	DSCF3505.jpg
Views:	21
Size:	43.2 KB
ID:	260150

Be aware that my unit has the patch from PE Aug 1980 to allow inverted characters controlled by one of the other bits in the RAM... the veroboard in the picture and a sample of it in action.

Click image for larger version

Name:	IMG_3397.jpg
Views:	19
Size:	48.9 KB
ID:	260149Click image for larger version

Name:	IMG_2516.jpg
Views:	22
Size:	73.0 KB
ID:	260151
Timbucus is offline   Reply With Quote
Old 30th Jun 2022, 1:04 pm   #91
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

Ah, then it doesn't count . But thanks for giving it a shot.

Seriously, that extra bit of circuitry may be holding the video output signal at a set state until the next time it is changed, but if so then it represents an unexpected 'cure' for the jail-bar problem even if you never intend to use the inverse-character feature. I would find those very faint vertical lines perfectly tolerable.

I also note that your VDU seems to be RF-connected so the resulting modulated then demodulated picture will be less hard edged than the one you would get via a direct composite connection.
SiriusHardware is online now   Reply With Quote
Old 30th Jun 2022, 1:34 pm   #92
Mark1960
Heptode
 
Join Date: Mar 2020
Location: Kitchener, Ontario, Canada
Posts: 834
Default Re: Yet another MK14 tape interface (ESP32).

Quote:
Originally Posted by Timbucus View Post
Tried to capture a picture of an all white MK14 screen using my Replica SOC VDU on my LCD in the workshop it is pretty poor so used the CRT in the Study. This is taken in manual mode on my Camera - as you can see there are faint lines that correspond to the jailbar position but, the blurring makes them almost unnoticeable.
How did you generate the all white screen? Was it filling the memory with FF and using graphic mode, or filling with 00 and using inverted graphic mode? Second option is likely to give white jailbars on a white screen.
Mark1960 is online now   Reply With Quote
Old 30th Jun 2022, 2:16 pm   #93
Timbucus
Octode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 1,174
Default Re: Yet another MK14 tape interface (ESP32).

@Sirius - it is actually using a composite tapped from the entry to to the modulator, you can just see the connector in the photo. @Mark I used the FF in Graphic mode - they appear as quite grey more so than in the photo.

Just tried to experiment again and my VI board will no longer program with the PI key programmer - I assumed one of the chips (Like my 365 - I actually use an 80C95 in that) had gone marginal as it seems to step through with keypad but, My JMPecision with the V1 OS also seems to fail (even with the ols os flag in send14 set correctly) - maybe my PI0 is faulty! Argghhh
Timbucus is offline   Reply With Quote
Old 30th Jun 2022, 2:32 pm   #94
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

Try using the Key14 single key test program just to check operation of all optos, etc. May just be a problem with a single key, or row, or column, on the opto interface. Send14 is so fast that it is very difficult to see if there is a fault.

Also, in the past you have sometimes forgotten that the wiring to the keypad edge connector on JMP PCBs vs. every other MK14 version is different, even though it was you who originally discovered that.
SiriusHardware is online now   Reply With Quote
Old 30th Jun 2022, 2:43 pm   #95
Timbucus
Octode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 1,174
Default Re: Yet another MK14 tape interface (ESP32).

Great minds think alike - I tried my old Vero version with the same PI and it works so must be one of the Opto's - I did try key14 but, it seemed indeterminate (it has much longer hold times on the GPIO than my finely tuned versions of Send) so will do some investigation with a meter - I am certain I do not have any spare Opto's of course as I used them building the neat Slothie unit

Yes the different key layouts can be an issue I actually have send14 and send14j which use the different layouts and as I have OS 1 in the JMP that version has the flag set.
Timbucus is offline   Reply With Quote
Old 30th Jun 2022, 3:05 pm   #96
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

We are very much hijacking Coolnaz2's thread now but if you used SMD TPL185s I have bucketloads of those here at work so if you need some just say so and I will send some down. I still have a couple of 6116 RAMs of yours which need to go back to you in any case. Let me know via PM.
SiriusHardware is online now   Reply With Quote
Old 1st Jul 2022, 5:31 pm   #97
coolsnaz2
Triode
 
Join Date: Aug 2020
Location: Wallington, Greater London, UK.
Posts: 34
Default Re: Yet another MK14 tape interface (ESP32).

Hi all, a few questions.

Timbucus, can the composite video from the MK14 VDU card be put into a AV to HDMI converter? Do I need any additional components? I enlarged the picture of your VDU board but was unable to see how you have connected the socket.

My EEPROM/RAM board currently uses a 74LS04 (Not gate) and 74LS08 (And Gate) to decode the address lines A9, A10, A11 and NRDS. See attached. Is there a more efficient way to decode these lines, ie 1 chip instead of 2.
001x (A11,A10,A9,A8) for Eprom at 0200, and 01xx for Ram at 0400.

Is there a replica VDU board available?

Is there any test software you can run on the MK14 that will test the components, ie Memory, Display and I/O chip.

Thanks in advance for your answers.
Attached Thumbnails
Click image for larger version

Name:	Screenshot_20220701-134230_Logic Gate Simulator.jpg
Views:	11
Size:	23.8 KB
ID:	260217  
coolsnaz2 is offline   Reply With Quote
Old 1st Jul 2022, 7:00 pm   #98
Mark1960
Heptode
 
Join Date: Mar 2020
Location: Kitchener, Ontario, Canada
Posts: 834
Default Re: Yet another MK14 tape interface (ESP32).

You could try a 74ls155 or 74ls156. The 156 would need pull up resistors on the outputs but might be easier to find.
Mark1960 is online now   Reply With Quote
Old 1st Jul 2022, 9:09 pm   #99
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

Quote:
Is there a replica VDU board available?
An actual replica of the SOC VDU board like the original one you have, yes, but only from one source as far as we know, and that is from the same Czech guy (Martin Lucasek) who produced the very authentic looking issue V replica PCBS. I don't know if he has any left, or intends to make any more. Have a look here:-

https://www.8bity.cz/2018/mk14-vdu-v...-unit-replica/

That is the one which Tim has.

Failing that, there is Karen Orton's OrtonView. See the latter part of the 'MK14 vdu' thread here for the story of the development of that PIC based hardware emulator of the SOC VDU.

https://www.vintage-radio.net/forum/...d.php?t=162766

Some time later, Slothie made a PCB for Karen's original design. During testing we discovered there was a problem with occasional memory corruption which was first resolved via a crude method (capacitors on the high address lines) and then by a more elegant chip solution, both developed by Mark1960. It works impeccably as long as you add Mark's fix. The video output from Ortonview is via composite video, rather than via a modulator.

https://www.vintage-radio.net/forum/...d.php?t=181460
SiriusHardware is online now   Reply With Quote
Old 1st Jul 2022, 9:26 pm   #100
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 8,628
Default Re: Yet another MK14 tape interface (ESP32).

Quote:
Is there any test software you can run on the MK14 that will test the components, ie Memory, Display and I/O chip.
Not as such. Sounds like a job for you.

There is a method you can use to crudely 'manually' check the I/O ports of the 8154 just using the monitor, see this post and the several after it:

https://www.vintage-radio.net/forum/...&postcount=155

Slothie wrote a RAM tester program but I can't for the life of me remember where it is, Timbo is usually the best at digging up things like that.
SiriusHardware is online now   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 10:10 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.