[HN Gopher] Refurb weekend(s): Commodore/MOS KIM-1
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Refurb weekend(s): Commodore/MOS KIM-1
Author : zdw
Score : 42 points
Date : 2023-07-08 14:38 UTC (1 days ago)
(HTM) web link (oldvcr.blogspot.com)
(TXT) w3m dump (oldvcr.blogspot.com)
| JKCalhoun wrote:
| Fortunately there are a number of KIM-1 replicas for someone
| wanting to play with an early 8-bit computer but either don't
| want to pay the high price for an original or don't want to end
| up worrying about restoration of an artifact like this guy, ha
| ha.
|
| I have built two replicas now, the most recent was the PAL-1 [1]
| kit. I also built one from Briel Computers some time ago but his
| business appears to have disappeared.
|
| The nice thing about the KIM-1 replicas/clones, as opposed to
| some of the Arduino or Raspberry Pi based ... emulators? .., is
| of course the real 6502 chip as the CPU.
|
| Also nice about the KIM-1 in general is that the six 7-segment
| LED displays give you both the address and data at that address
| at once (and in hexadecimal). Other early 8-bit machines of
| course displayed data in binary (via das blinkenlights).
|
| (Another clone that looked to be outstanding was made by Corsham
| Technologies. Sadly the man behind the clone died just a month
| ago and so those machines have also stopped production.)
|
| [1]
| https://www.tindie.com/products/tkoak/pal-1-a-mos-6502-power...
|
| [2] https://www.corshamtech.com/product/kim-clone/
| classichasclass wrote:
| (author) Bob's replica unit looked really cool but I never got
| around to picking one up before his untimely death. It's always
| nerve-wracking working on a museum piece but this one is very
| special to me.
| jgrahamc wrote:
| Yes, his death is so sad. I wanted to get one of his KIM-1
| I/O boards. RIP.
| jacquesm wrote:
| The KIM-1 was one of my very first machines, I faithfully lugged
| it with me across many moves and one day it just disappeared. I
| still have faint hope that it's somewhere in one of my (too) many
| storage boxes but I suspect it just got lost. Really a pity
| because they are becoming more and more rare.
|
| Nice to see this one restored to its full glory. Trying to
| explain to my kids that once upon a time the full working memory
| of my computer was a very small fraction of one of the photos
| they share online was a fun experience.
|
| Note the gorgeous very high quality circuit board.
|
| As for the article: I'm not particularly impressed with the
| workmanship, as a kid I'd repair boards of this and higher
| complexity regularly and lifting traces and cutting traces while
| doing such a simple repair would not normally happen to me. One
| way to do better would be to use a good quality rework iron with
| a vacuum pump. Not cheap but if you work on old and nice hole
| through stuff like this well worth the investment. Otherwise you
| end up overheating the board. A repair should look more or less
| as if the board wasn't touched, apart from maybe the gloss on the
| solder. And make sure to use 63/37 'old fashioned' solder.
| [deleted]
| classichasclass wrote:
| (author) Hey now, not all of us are adept at this. I appreciate
| the tips but we all start somewhere. I was particularly
| motivated on this one because it's a relatively simple machine
| that's special to me and I should be able to maintain it.
| jacquesm wrote:
| Hey there, yes, I'm happy you managed to fix it. But you
| probably would have done a much better job by first
| practicing IC removal on a bunch of older boards, by the time
| you can do that with your eyes closed you can practice on the
| heirlooms ;)
|
| Of course it's yours and you're absolutely within your rights
| to work on it and your analysis of what was wrong was spot on
| (and very impressive). But these are getting rare.
|
| I wonder what caused the chip to fail, once in the circuit
| they are normally quite solid. Keep 'm rolling ;)
| classichasclass wrote:
| I appreciate that. Everything is a learning experience.
|
| I'm told that RAM is a common failure on KIMs, though this
| was the first one I've personally experienced with my own
| set.
| jacquesm wrote:
| On mine the LM565 chip had gone, as well as a diode, when
| I got it from a guy in Almere who worked at the same bank
| where I worked. That's also the only one that I ever came
| across here in Europe, there can't have been that many
| here. I really should make an effort to see if I can find
| it again.
|
| And yes, everything is a learning experience, I'm pretty
| sure you'd have a much easier time of it if you did it
| again. Please do consider getting a proper rework kit,
| it's well worth it if you're going to do this sort of
| thing regularly. And in a strange way those skills are
| getting more valuable again, fewer and fewer people
| around that can repair vintage stuff. One of my 'side
| projects' is restoring vintage DX-7's, they're fun to
| work on and there are enough of them around that even if
| you buy one that seems to be total junk you'll be able to
| get another one going and have parts left over.
| skipkey wrote:
| It was the first thing I learned to program on. My father went
| to a conference where they gave him one as swag, and he gave it
| to my older brother and me. I was, I think, seven years old or
| so.
|
| Writing code that we hand assembled taught me a lot. It's
| probably still in a box at my folks place somewhere in the
| garage.
| vertnerd wrote:
| I "lost" mine in a move about 40 years ago. I have been in
| mourning ever since.
| jgrahamc wrote:
| I own an original KIM-1 (that shipped on July 27, 1976; revision
| A, ceramic 6502/6530). See https://imgur.com/a/iCClwCb It works
| flawlessly. I actually did some programming of the KIM-1 in the
| mid-1980s for industrial control:
| https://blog.jgc.org/2013/04/how-i-coded-in-1985.html
| classichasclass wrote:
| That looks nearly identical to my own Rev A. The one I have the
| prior owner built a small plywood and acrylic enclosure for.
| It's the original enclosures for these things that their
| original owners built that really give them personality, like
| this suitcase unit.
|
| The oldest KIM I'm personally aware of is a original (i.e.,
| pre-Rev A) with a 6502 that still has the ROR bug. I should ask
| its owner what the date codes on that are.
| jgrahamc wrote:
| Interesting. I should write some code for mine and check for
| that bug. I assume it was fixed by the time this shipped (my
| CPU is week 21 of 1976). I have an acrylic case for mine to
| protect it.
| classichasclass wrote:
| You might indeed have one with a bad ROR. My MOS
| documentation for the time says ROR would be "available"
| after "June, 1976." The Rev A here is 30th week 1976 and
| does not have the bug.
| metadat wrote:
| Why would one choose to work with a bare computer board atop a
| layer of tinfoil like this?
|
| https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj...
|
| Perhaps the tinfoil was clipped to a ground? Would it then be
| protected from static shocks and other invisible (to the naked
| eye) damage?
|
| Historically I've used flattened cardboard outside on top of a
| brick patio, and ensured I touch a grounded circuit before e.g.
| replacing capacitors. No e-deaths due to static yet, though my
| equipment is nearly all from ~circa 1999 or newer, and I believe
| newer equipment typically incorporates some static protections
| into designs.
|
| TFA's PCB layout connections are so flowy and beautiful, they
| remind me of a past HN submission about rounded PCB circuit
| wiring: "Melting KiCad"
| https://mitxela.com/projects/melting_kicad /
| https://news.ycombinator.com/item?id=31108652
|
| p.s. this is an amazing writeup, thank you to the OP for
| submitting and to the author for taking the time and care.
| Really, really cool. This reminds me a bit of a Ken Sherriff
| analysis https://righto.com (!) <3
| classichasclass wrote:
| (author) Thanks! No special reason for the foil other than
| being a convenient heat resistant shield that can be disposed
| of so I'm not scattering solder bits around the back room.
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