UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio 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 27th Apr 2018, 6:12 pm   #41
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

Slothie, PM Sent.
SiriusHardware is offline   Reply With Quote
Old 30th Apr 2018, 4:47 pm   #42
Slothie
Pentode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 130
Default Re: MK14 schematic revisions

PROMs in the post! There's a sticky address label with stamps on in the envelope.The edge of the label has 'high' and 'low' stickers for the proms!
Slothie is offline   Reply With Quote
Old 30th Apr 2018, 5:00 pm   #43
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

OK, I'll look out for them and have everything juiced up and ready.
SiriusHardware is offline   Reply With Quote
Old 3rd May 2018, 7:08 pm   #44
gertk64
Diode
 
Join Date: May 2018
Location: Zwolle, Netherlands
Posts: 3
Default Re: MK14 schematic revisions

Just managed to get first signs of life out of my MK14 replica,
now waiting for the 80L95, well 80C95 or 74LS365 and the RAM chips (ordered the AM9111 also).

I did have a fight with the new 74LS157 multiplexers (did not work as latch) and the fact that my temporary substitute RAM (HM6116) seemed to dislike the floating read, write and address lines of the CPU.

With 4 pullups on the top address lines and the read and write lines from the CPU the display suddenly got a lot more stable but still no 0000 00. I swapped the 74LS157 with an old set of 74LS257 (tri-state version of the LS157) and tada, steady display.

For testing the keyboard I used a DIL plug with a small PCB on it which carried a LS32 and a LS367 I had lying around and I could enter some data.
Attached Thumbnails
Click image for larger version

Name:	2018-04-29 16.53.56.jpg
Views:	74
Size:	54.3 KB
ID:	162216  
gertk64 is offline   Reply With Quote
Old 3rd May 2018, 7:57 pm   #45
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

Slothie's PROMs arrived, but I was surprised to find that they were 'Tesla' branded MH74S571 Proms, not the expected National Semiconductor DM74S571s which I know my ALL07A programmer can program. My fault for just assuming they would be National Semiconductor 'DM' prefixed devices.

The All07A programmer only specifically supports the Nat Semi part, and does not (as programmers sometimes do) have a slow-but-sure 'Generic' 74S571 option. So the dilemma is, whether to try to program them as DM74S571s and hope that the algorithm, programming voltages and so on are the same or similar enough.

Several comments in forums suggest not: On Mattieu Benoit's site someone has made a one - off .exe for for the ALL03 (sadly not my ALL07) programmer, which already natively supports the DM74S571, to allow it to program the MH74S571 as well. If someone went to all that trouble it seems likely that programming these devices as per DM74S571 does not work, or does not work reliably.

I don't want to ruin Slothie's expensive one-shot PROMs. Slothie has already said that it's OK to return them unprogrammed, but I'm open to last-minute persuasion from anyone who has, for example, successfully programmed MH74S571s 'as DM74S571s'

I have found one currently available programmer, the Elnec Beeprog2 - also available badged as Dataman - which explicitly lists support for the MH device.

https://www.elnec.com/en/products/un...mers/beeprog2/

It is not cheap, and on the only marginally cheaper cut-down version, support for BPROMs is dropped altogether.

Another option would be to buy a set of programmed PROMs from this Czech site,

http://www.8bity.cz/2018/final-repli...mk14-sinclair/

...which is selling replica MK14 PCBs, Keypad overlays and programmed PROMs. I'm sure the site owner would sell a set of programmed PROMs only, or even program a set sent to him, if asked. It seems likely that his PROMs are the MH... flavour, so he must have the means to program those.

Or, this well documented Arduino project, clearly meant to program the 'original' DM74S571, could be adapted and the timing modified if there is sufficient data available about the MH74S571...

https://hackaday.io/project/25953-pr...rom-programmer

You could always also build the original Science Of Cambridge PROM programmer add-on for the MK14, the paradox being that on the face of it, it requires a working MK14 to operate it: Of course an Arduino or PIC could be used more conveniently nowadays. MK14man's definitive website concerning all things MK14 seems unavailable at the moment, so I can't link to the manual which contains details of the circuit, connections and software support routines - but I think Slothie probably has it anyway.

Slothie, give it a couple of days and we'll see if anything interesting comes up, or just say the word and I'll send them off back to you sooner.
SiriusHardware is offline   Reply With Quote
Old 3rd May 2018, 8:04 pm   #46
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

Quote:
Originally Posted by gertk64 View Post
Just managed to get first signs of life out of my MK14 replica.
Well done! May we ask which type of PROMs you are using, and whether you bought them programmed or programmed them yourself?
SiriusHardware is offline   Reply With Quote
Old 3rd May 2018, 8:32 pm   #47
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

Further, this website

https://www.mikesarcade.com/cgi-bin/...ge=PromRef.txt

An excerpt from which is here:

Code:
512*4
   +------+
A6 |1   16| Vcc
A5 |2   15| A7
A4 |3   14| A8
A3 |4   13| CE/
A0 |5   12| O1
A1 |6   11| O2
A2 |7   10| O3
GND|8    9| O4
   +------+

   Signetics     MMI     TI       Harris  Raytheon  AMD      National  Intel
   ---------     ---     --       ------  --------  ---      --------  -----
TS 82S131 (50ns) 6306-1  -        7621-5  29611     27S13    74S571    3622
   82S131A(30ns) 63S241  -        7621A   -         27S13A   74S571A   3622A

OC 82S130 (50ns) 6305-1  -        7620-5  29610     27S12    74S570    3602
   82S130A(33ns) 63S240  -        7620A-5 -         27S12A   74S570A   3602A

..Suggests that the Philips / Signetics 82S131 and the AMD 27S13 are drop-in equivalents for the National Semiconductor DM74S571. My programmer can program all three of these types.
SiriusHardware is offline   Reply With Quote
Old 3rd May 2018, 9:15 pm   #48
Slothie
Pentode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 130
Default Re: MK14 schematic revisions

Quote:
Originally Posted by SiriusHardware View Post

https://hackaday.io/project/25953-pr...rom-programmer

You could always also build the original Science Of Cambridge PROM programmer add-on for the MK14, the paradox being that on the face of it, it requires a working MK14 to operate it: Of course an Arduino or PIC could be used more conveniently nowadays. MK14man's definitive website concerning all things MK14 seems unavailable at the moment, so I can't link to the manual which contains details of the circuit, connections and software support routines - but I think Slothie probably has it anyway.

Slothie, give it a couple of days and we'll see if anything interesting comes up, or just say the word and I'll send them off back to you sooner.
I've seen the hackaday link and the mk14 design and sketched out a design for one, using an ATMEGA328 to drive it rather than bootstrapping the mk14!
Hang onto the proms for a while in case we get any response on here. I'm still waiting for stuff to arrive, and to get some free time! As i said in my PM if it comes to it I can program a 2716 and make an adaptor on stripboard so I can plug it into the mk14 until a prom solution appears. If I want to keep it "retro" I found an eprom programmer for my PET in a box from the loft so I could use that!

The idea of making a programmer is growing on me since one day I'd like to make an Acorn 1, and that uses 74S571s too! I'd be able to tweak the timing capacitors for the Tesla chips

I'll query the guy in the Czech republic too, looking at pics of his replica he is clearly using Tesla 74S571 chips, not surprisingly since I imagine the fall of communism there probably revealed warehouses full of vintage electronics. Tesla are now a mojor supplier of valves nowadays I understand!
Attached Files
File Type: pdf promblower.pdf (69.6 KB, 56 views)
Slothie is offline   Reply With Quote
Old 4th May 2018, 10:51 am   #49
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

I'm informed by M. Benoit, who kindly replied to my query by email, that I definitely should not try to program Tesla 'MH' devices using the 'DM' algorithm, unfortunately.

The Hi-Lo ALL03 can do the MH series chips if you utilise a special bit of software which Matthieu has on his site, but that software does not run on the ALL07 as it stands.
SiriusHardware is offline   Reply With Quote
Old 5th May 2018, 4:24 pm   #50
gertk64
Diode
 
Join Date: May 2018
Location: Zwolle, Netherlands
Posts: 3
Default Re: MK14 schematic revisions

Quote:
Originally Posted by SiriusHardware View Post
Well done! May we ask which type of PROMs you are using, and whether you bought them programmed or programmed them yourself?
I got them pre-programmed. With the latter version with the tape routines and the "0000 00" startup display.

Got the AM9111 RAM chips today, will put them in this weekend.
gertk64 is offline   Reply With Quote
Old 5th May 2018, 10:50 pm   #51
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

Quote:
I got them pre-programmed. With the latter version with the tape routines and the "0000 00" startup display.
In that case I think yours will be MH74S571 PROMs rather than original DM74S571s?

Let us know how you get on. I should think it will go OK because you have already proved the system using substitute RAM.

Until TonyDuell mentioned it, I didn't know the 74LS157s could be so troublesome. I should look into sourcing some good working spares for my MK14 while the originals are still working.
SiriusHardware is offline   Reply With Quote
Old 10th May 2018, 12:04 pm   #52
gertk64
Diode
 
Join Date: May 2018
Location: Zwolle, Netherlands
Posts: 3
Default Re: MK14 schematic revisions

My proms are the TESLA brand MH74S571. I also have a set unprogrammed TESLA proms which I bought earlier.

The AM9111 RAM chips have arrived from Israel and are working fine.

I also got two 80C95 (instead of the hard to find 80L95) from littlediode in the UK and it works fine too.

From Martin (the Czech guy) I got the tip I could also have used the 74LS365 instead of the 80L95. Ah well, my MK14 is complete now
gertk64 is offline   Reply With Quote
Old 10th May 2018, 3:11 pm   #53
Slothie
Pentode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 130
Default Re: MK14 schematic revisions

Congratulations! Whats next, an Oric Atmos?
Slothie is offline   Reply With Quote
Old 10th May 2018, 6:55 pm   #54
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

Well done, Gert.

The primary address range of the OS PROMS is from 0000H-01FFH. I believe the Czech replicas (one of which I think you must have) are of the issue V MK14. Could you look at address 0200H onwards to see if there is a copy (image) of the PROM code there? I would be interested to know if the address decoding modification (discussed earlier in this thread) has been incorporated into those replicas.

What was the first program you ran on your replica? 'Message', from the original manual, is often popular as you can see something happening and then have some fun trying to devise your own scrolling message without using 'K', 'M', 'V', 'W', 'X', or 'Z'.

You mentioned that you had to use 74LS257s instead of the 74LS157s you had originally. What prefix / brand were the 74LS157s which did NOT work?

I have found a UK source for original Nat-Semi branded DM74S571 PROMs, a pair of which arrived today. At almost 12 GBP for the pair they weren't especially cheap but in light of the discovery that I can not program the Tesla MH74S571 devices, I thought I had better obtain a pair of National Semiconductor 'DM' prefix devices to program up and keep as spares for my MK14.

I've asked a one-off favour from someone who believes they can program Slothie's Tesla MH74S571 PROMS, and we are awaiting the outcome from that.

For anyone else, I'm happy to program (and test) PROMs for an MK14 if they are any of the following devices:

National Semiconductor DM74S571 (but not DM74S571A)
Philips / Signetics 82S131 -or- 82S131A
AMD AM27S13 (but not 27S13A)

Obviously, they must be unused blanks because this type of PROM can not be erased and reprogrammed.

I am NOT able to program the Tesla MH74S571. I believe Slothie has a medium-term plan to make a specific programmer for those...
SiriusHardware is offline   Reply With Quote
Old 10th May 2018, 7:07 pm   #55
Slothie
Pentode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 130
Default Re: MK14 schematic revisions

Quote:
I am NOT able to program the Tesla MH74S571. I believe Slothie has a medium-term plan to make a specific programmer for those...
When I've finished my MK14 and refurbished my PET and nixie calculator I'll be on it!
Slothie is offline   Reply With Quote
Old 13th May 2018, 4:26 pm   #56
kan_turk
Pentode
 
kan_turk's Avatar
 
Join Date: Mar 2014
Location: Dublin, Ireland
Posts: 243
Default Re: MK14 schematic revisions

Quote:
Originally Posted by Slothie View Post
Yes. a guy in California was selling them (I think it may have been the one you pointed out) so I bought 4. They arrived Thursday! So I have those and some 65X61 chips, and there is a link on the bottom of the board to select which type (they all have to be the same type).

If John can find his 7408s then I have a source for all the chips!
I just need to get my PROMs programmed; I have the schematic for the MK14 prom programmer, which I could hook up to an arduino. I just need to be sure it works first time because I only have the two!! Did I see you say you had a 74S571 programmer? could I ask you to program them for me if I sent you the PROMS and return postage?

The 7408 has a 130 ohm resistor in the output (see schematic) which would limits the current through the LED to about 25ma, which multiplexed 8 ways is an average of ~3ma which is the correct sort of average current for the LEDs in the bubble display.
Hi
Just to let you know - after a bit of archaeological excavation in what I laughingly call my stores, I located the 7808s
If you pm me your postal address and let me know how many you require I'll send them on their way - I'm still surprised that I found them as well as other long forgotten 'treasures'

Kindest regards
John
kan_turk is online now   Reply With Quote
Old 13th May 2018, 6:32 pm   #57
kan_turk
Pentode
 
kan_turk's Avatar
 
Join Date: Mar 2014
Location: Dublin, Ireland
Posts: 243
Default Re: MK14 schematic revisions

That should be 7408s of course

J
kan_turk is online now   Reply With Quote
Old 13th May 2018, 8:13 pm   #58
Slothie
Pentode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 130
Default Re: MK14 schematic revisions

Oops when I didn't hear anything I thought you'd not been able to find them, and got some off eBay for about 60p each! Sorry if I've put you to unnecessary trouble. When everything arrives I should have everything now, assuming a pair of the 74LS571's I have will work. I have ordered some new ones, and if they don't work in the MK14 I have some in various old computers that I can swap them out for.
Slothie is offline   Reply With Quote
Old 13th May 2018, 9:16 pm   #59
SiriusHardware
Nonode
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 2,800
Default Re: MK14 schematic revisions

Quote:
assuming a pair of the 74LS571's I have will work.
74LS157s?
SiriusHardware is offline   Reply With Quote
Old 13th May 2018, 9:26 pm   #60
kan_turk
Pentode
 
kan_turk's Avatar
 
Join Date: Mar 2014
Location: Dublin, Ireland
Posts: 243
Default Re: MK14 schematic revisions

Quote:
Originally Posted by Slothie View Post
Oops when I didn't hear anything I thought you'd not been able to find them, and got some off eBay for about 60p each! Sorry if I've put you to unnecessary trouble. When everything arrives I should have everything now, assuming a pair of the 74LS571's I have will work. I have ordered some new ones, and if they don't work in the MK14 I have some in various old computers that I can swap them out for.
No trouble - sorry but just took a while to find them - it gave me a chance to put a bit of order on my stores and I now have a better handle on what I have.
Best of luck with the project - I will be following thread with interest

Rgds
John
kan_turk is online now   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 11:46 am.


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 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.