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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 10th Dec 2023, 7:19 pm   #121
circuitryboy
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Default Re: Nat Semi SC/MP Low Cost Development System

Bazinga! Excellent work.
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Old 5th Jan 2024, 3:24 pm   #122
Realtime
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Default Re: Nat Semi SC/MP Low Cost Development System

Here's the completed schematic for the Telekit 537 PCB.

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Name:	Key Component Diagram.jpg
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I'll be starting a new thread to canvas thoughts on creating a replica (a Telekit II, if you will)
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File Type: pdf TELEKIT_Schematic Rev 1.pdf (374.9 KB, 23 views)
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Old 5th Jan 2024, 3:49 pm   #123
Phil__G
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Default Re: Nat Semi SC/MP Low Cost Development System

So how much of the original eprom dump turned out to be good Ian?
Did you have to re-write the whole thing, or did you work around sections from the eprom?
...and how does the overall finished code compare with the original Natsemis code?
All fascinating stuff, maybe a good start to the new thread?
Cheers
Phil
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Old 5th Jan 2024, 5:54 pm   #124
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Default Re: Nat Semi SC/MP Low Cost Development System

Quote:
Originally Posted by Phil__G View Post
So how much of the original eprom dump turned out to be good Ian?
The majority of it was good, I'd say 90%. I added around 50 bytes to the NatSemi code.

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Originally Posted by Phil__G View Post
Did you have to re-write the whole thing, or did you work around sections from the eprom?
...and how does the overall finished code compare with the original Natsemis code?
No re-write, just took a long time to understand what all the variables are there for (still a few undocumented ones). I added new code as required and amended a small amount of existing code. In Version 11 (see #120) I've identified added code with ;NEW and modifications with ;CHANGE. You'll see there's been hardly any change, but the key thing was initialising variables and setting the shift registers into the correct mode to write out to the display while simultaneously reading back from the key matrix.

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All fascinating stuff, maybe a good start to the new thread?
Cheers
Phil
I want to document what I've learned about the LCDS and Telekit before moving off to something else. Maybe something along the lines of Tim's excellent SCRUMPI book.

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Old 5th Jan 2024, 6:24 pm   #125
Phil__G
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Default Re: Nat Semi SC/MP Low Cost Development System

Oooh yes. Signed copy, please!
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Old 6th Jan 2024, 1:08 am   #126
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Default Re: Nat Semi SC/MP Low Cost Development System

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Originally Posted by Realtime View Post
>>
Maybe something along the lines of Tim's excellent SCRUMPI book.

Attachment 290603
Thanks for that link - I'd somehow missed seeing the existence of this before, despite previously following links to other (Softy etc) stuff on Tim's Onedrive, that were too large to attach here.
- And having a quick read, I've only just discovered that the origins of 'MK14' was "short for Microcomputer Kit 14 – the number being the least number of chips it can run with."
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Old 25th Feb 2024, 5:53 pm   #127
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Default Re: Nat Semi SC/MP Low Cost Development System

A quick update on whether this TELEKIT is an early prototype or not. As shown in post #16, the wiring mod's on the back of the board were pretty low quality and as we learned, the SW definitely wasn't complete. So that points to it being a early development model. But I think what has clinched it is the attached photo.

I decided to remove the silk-screened keypad overlay in preparation for when I find a replacement working keypad and to my surprise under the silk-screened part was a hand drawn keypad, even including the Nat Semi logo. That must have been done while they were waiting for the overlay to be printed.

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Name:	Early Keypad.jpg
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ID:	293634

So all of a sudden that broken keypad is looking a lot more interesting and will definitely get stored with the other component parts of the LCDS.
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File Type: zip Early Keypad.zip (982.8 KB, 3 views)
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