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

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Old 26th Mar 2021, 2:33 pm   #241
Buzby123
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Default Re: I found it! A very sorry looking MK14.

Micky has awoken ...
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Old 26th Mar 2021, 2:39 pm   #242
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Default Re: I found it! A very sorry looking MK14.

That didn't take long! Now you have to decide how far to go with the restoration to its 'historic' form factor...
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Old 26th Mar 2021, 3:04 pm   #243
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Default Re: I found it! A very sorry looking MK14.

I'm not restoring the daughterboard system, it's too messy and precarious. Too many chances to damage the expensive bits. If I was to build a 'new' daughterboard I'd take a completlely different tack about it.

Micky will be going back in his cabinet, the lamps and switches on there should still work, as they are all driven from the 8154 edge connector. The cassette interface will be reinstalled, then I'll have to find a way to test that. The keyboard and display should work, those are the first things I'll be testing.

It's been a long and arduous journey to get Micky alive again.

I could not, and maybe would not, have done it without the help and support from this forum.

Thanks to you all.

Buzby
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Old 26th Mar 2021, 5:36 pm   #244
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Default Re: I found it! A very sorry looking MK14.

They make a nice couple. I'm guessing you have a 4.00MHz crystal in Vicky, if so Micky will be significantly faster than his younger sister.

It would be good if you could post a nice YT video of it working when it's all up and running and back in the original enclosure.
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Old 26th Mar 2021, 5:55 pm   #245
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Default Re: I found it! A very sorry looking MK14.

As far as testing the cassette interface is concerned any Laptop or PC of a certain age will have proper audio inputs and outputs which you can use in conjunction with something as simple as Windows 'Sound Recorder' or something a bit more full featured (but free) like 'Audacity' to record the audio output from the MK14 Cassette Interface and play it back into it.

Once you have an MK14 program saved as an audio file you can play it back into the MK14 using almost anything, I successfully used both an old Win XP netbook and a little Creative Technology MP3 player to play MK14 tape files back into the machine when I was testing the hex-to-audio conversion software by twostickes (see his recent thread).

The main thing, if you are using anything which has stereo audio output to play files back in, is to use only one audio output channel, either left or right, don't join them both together to connect to the mono input of the cassette interface. I have a lead made up which has a stereo plug at the laptop / MP3 / Smartphone end and a mono plug at the MK14 interface end. In the stereo plug, only the left channel audio output is connected through to audio-in at the 'mono' MK14 end.
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Old 26th Mar 2021, 6:24 pm   #246
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Default Re: I found it! A very sorry looking MK14.

Quote:
Originally Posted by SiriusHardware View Post
I'm guessing you have a 4.00MHz crystal in Vicky, if so Micky will be significantly faster than his younger sister.
Nope, Vicky's xtal is labelled 4.433, so I'm expecting it to be 4.433618, same as Micky.
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It would be good if you could post a nice YT video of it working when it's all up and running and back in the original enclosure.
I certainly will !.
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Old 26th Mar 2021, 6:43 pm   #247
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Default Re: I found it! A very sorry looking MK14.

I did actually buy a 4.43MHz crystal to put in my issue VI as well because some of the old manual software such as 'Music Box' and 'Digital Clock' depends on the crystal being that frequency, but then the prospect of reconnecting my VDU (and Karen's 'Ortonview' alternative), both of which prefer 4.00MHz, was just too good to resist so I never have changed it.

Did you see that original MK14 in another thread which had the keypad restored by soldering ultra low profile SMD switches (we thought they were domes at first) to the keypad fingers and then placing an authentic looking keypad overlay over the top? It was so nicely done I would consider doing that to mine if it did not already have a reasonable substitute keypad fitted in place of the original one.
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Old 26th Mar 2021, 6:58 pm   #248
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Default Re: I found it! A very sorry looking MK14.

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Did you see that original MK14 in another thread which had the keypad restored by soldering ultra low profile SMD switches ....
No, I haven't seen that. I'm not going to put a new keyboard on Micky. When he's in his case there is no need for one, but I probably will sneak in one of those Arduino downloaders.
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Old 26th Mar 2021, 7:14 pm   #249
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Default Re: I found it! A very sorry looking MK14.

You could maybe panel-mount a 15 way sub-D connector in a cutout on the right hand side of the enclosure and wire the external keypad connector to that. That way you don't have to have anything non-period inside the enclosure, you just plug your uploader of choice into the sub-D connector, load something up and then unplug it.

It would mean modifying the 'historic' housing slightly, but sub-D connectors are as 1970s as they are current, so it would look perfectly in keeping. It would also let you plug in a high quality external keypad or even a keyboard with more keys on it, should the mood ever take you. (The MK14's row / column matrix can support quite a few more than the 20 keys on the original keypad).

Edit: A full sized keyboard would need to use all of the row / column lines including two which the standard keypad does not use, so if that was the plan it would be better to go up to a 25-way connector (there are 19 way sub-Ds but they are rather rare now).

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Old 26th Mar 2021, 7:46 pm   #250
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Default Re: I found it! A very sorry looking MK14.

That's a good idea.

I'm not going to be able to do much over the weekend, so it will be next week before Micky gets back in his case. ( Actually, I'm putting Vicky in first, just to do a test without risking Micky. )
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Old 26th Mar 2021, 7:48 pm   #251
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Default Re: I found it! A very sorry looking MK14.

Nice result on getting it going again and a sensible idea to use Vicky to test.
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Old 26th Mar 2021, 8:58 pm   #252
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Default Re: I found it! A very sorry looking MK14.

Quote:
Originally Posted by SiriusHardware View Post
I did actually buy a 4.43MHz crystal to put in my issue VI as well because some of the old manual software such as 'Music Box' and 'Digital Clock' depends on the crystal being that frequency, but then the prospect of reconnecting my VDU (and Karen's 'Ortonview' alternative), both of which prefer 4.00MHz, was just too good to resist so I never have changed it.
When i tried to buy a 4MHz and 4.43MHz crystal I ended up with 50 of each.

I think the ortonview would work ok with the 4.43MHz, as its not synchronized to the 8060 anyway. Iíll try it when I get round to building one.
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Old 26th Mar 2021, 9:02 pm   #253
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Default Re: I found it! A very sorry looking MK14.

Quote:
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It would also let you plug in a high quality external keypad or even a keyboard with more keys on it, should the mood ever take you. (The MK14's row / column matrix can support quite a few more than the 20 keys on the original keypad).
Was there ever a suggested connection matrix for adding a qwerty keyboard to the MK14 ?
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Old 26th Mar 2021, 9:12 pm   #254
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Default Re: I found it! A very sorry looking MK14.

The key matrix is 4x10, so 14 wires needed. A 15 way sub-D would work, but I've got plenty 25's, so a 25 it will be !.

Way back in the day, I had access to some neat hole punches, one for each size of sub-D. This time it will be drilling and filing !
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Old 26th Mar 2021, 9:20 pm   #255
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Default Re: I found it! A very sorry looking MK14.

Once the SC/MP is running under your program's control it is obviously up to you which row / column nodes you choose to scan and how you choose to respond to them, but I don't think any wiring convention ever got as far as being on paper.

It was arguably the next thing in the pipeline, SOC hinted at their future plans in one or more newsletters which I am sure Tim can effortlessly produce a link to, but instead they made the ZX80, which begat the ZX81 and eventually the Spectrum, so it was probably just as well that they decided to leave the MK14 where it was.

For that reason, I don't think there was ever a 'standard' way of connecting a QWERTY keyboard but that leaves us free to invent one, perhaps utilising an existing standard keyboard such as the ZX81 membrane keyboard, still widely available.

A QWERTY keyboard would only really make good sense with an alphanumeric display permanently fitted, ie, VDU or OrtonView, along with an alternative OS to support them. So once again, we are really veering towards the evolution of the MK14 into a NIBL machine or something like it.
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Old 26th Mar 2021, 9:23 pm   #256
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Default Re: I found it! A very sorry looking MK14.

Quote:
The key matrix is 4x10, so 14 wires needed. A 15 way sub-D would work
Ah, you are forgetting about the two wires needed for the reset output from the uploader. That's too useful to leave out, it allows the uploader to force the MK14 back to the monitor if it already happens to be running a program, so it can upload another one.

Also, if you were using a deluxe external keypad you might want to have a reset switch on there as well.
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Old 26th Mar 2021, 9:41 pm   #257
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Default Re: I found it! A very sorry looking MK14.

It's a shame you don't have access to your specific hole cutters any more but one trick I used to use when cutting holes for sub-Ds was to find a PC interface card of any kind / sort which had the right size of 'D' connector on it, temporarily remove the vertical metal backplate from it and use that as a kind of stencil with which to draw the desired outline for the cutout, including the positions of the holes for the screw posts, by running an inedible ink marker around the inside edge of the cutouts for the connectors and the screw post holes. Remove the plate and you have exactly the right outline marked on the housing and ready to cut out with the screw post holes marked at the correct relative spacing.

An old motherboard backplate, or one from a serial port card or multi i/o card should have at least one 25-way cutout which you can utilise in that way - for 15-way you'd need to find an old soundcard with a 15-way 'game' (joystick / MIDI) port on it.
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Old 26th Mar 2021, 9:47 pm   #258
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Default Re: I found it! A very sorry looking MK14.

I like the PC-card template idea, I'll try that.

On another subject, has anyone got the full data sheet for the DM74S571 PROM ?. All the ones I can find just seem to be the first 3 pages of a much bigger document.
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Old 26th Mar 2021, 10:10 pm   #259
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Default Re: I found it! A very sorry looking MK14.

There's a 4 page Datasheet for the DM74S571, here:

http://theoddys.com/acorn/Semiconduc...iconductor.pdf

And it doesn't look like it end unexpectedly, although there may be a separate section in the original databooks (probably on various archive / bitsavers etc. websites) on programming their PRON's, from what I recall.

Edit: Attached is an edied version of the NS 1977 Memory databook, that has (1 page) programming procedure for these, and also has the contents index, which appears to show from page numbers order that the 74S571 datasheet had 5 pages in that version.

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Old 26th Mar 2021, 10:17 pm   #260
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Default Re: I found it! A very sorry looking MK14.

PDF pages 202-206 (5 pages) of this National Databook over on Bitsavers include a good description of how to program them. It's an entire book so it takes a little while to download.

http://www.bitsavers.org/components/...y_Databook.pdf

If you are thinking of programming one yourself don't forget there was an official MK14 PROM programmer from SOC, details attached. You seem to have working MK14s lying around all over the place now, so...

Bear in mind however that this and all other programmers which handle the DM74S571 can not program the Tesla MH74S571, the hardware method and timing for programming that device are just too dissimilar.

Also bear in mind that these devices are one-shot, you only get one go at getting it right.
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