The First Kino 74 Update in... 3 Years?

I was recently invited to bring the Kino 74 to the bay area to display it at the Vintage Computer Festival West (http://vcfed.org/wp/festivals/vintage-computer-festival-west-xi/).  While this was totally flattering and I would have loved to have gone, DefCon was right at the same time and I didn't actually get the note left in my guestbook until about a month after it was left and too late to make any different plans (not that I would ever EVER skip DefCon).

If I were going to display the thing, I would have loved to do a bit a cleanup and make it a little more presentable... and maybe kinda sorta make sure that it still works? That might be a good idea...  A week ago I pulled it out and fired it up for the first time in maybe two years and sadly, the day I always sort of expected as has arrived: my microcomputer has gone down. :-(

Ugh. I made this video, but so very much loathe hearing my own voice.

The Problem:

It's not utterly ruined or anything and still blinks lots of lights roughly in some sort of pattern, but it's not decoding instructions properly, a couple of LED wires for the front panel having broken loose of their solder joints.  I've also remembered just how horrible it is to program that thing.

The biggest design flaw in the computer, and believe me there are many, is that in its current form I can't realistically take it apart to fix these ultimately minor issues.  It's the equivalent of having to pull the whole engine out of your car just to change the oil, replace the wiper fluid or fix the brakes. Anything that's as cobbled together as this machine is will need a tune-up every one in a while so it'd be a shame to have to basically completely disassemble everything (short of pulling the chips off of the breadboards) every time it needed a tweak here and there.

I've fixed a couple of minor things before (or just ignored them), but this is the first time that the execution of the program is no longer working (i.e. instructions and data are not being properly handled), so something a little more deep-seated has gone wrong.  I've looked the thing over as best as I can without tearing into it and the one thing I spotted did not resolve my issues.  So it's time to talk pulling everything apart for the first time since it first went together!

The Plan:

In the coming months I'm going to detach each of the boards from one another, clean everything out, test all the chips and then reassemble everything presumably fixing any issues that have occurred. Great. Good plan John. We're done, right?

Unfortunately I have a move coming up (ugh) and don't want to have everything in pieces during that process, which has left me with some time to... reflect.  In my reflection it has occurred to me that this may be a good time to make some improvements in addition to fixing the current problems.

At issue is what to improve and what to leave as-is. If I'm going to keep this thing running into the future, some of these really fall under the "critical" improvements category. Other stuff is cosmetic. Finally, I'm flirting with the idea of upgrading the hardware and maybe even adding an instruction or two to make the kino 74 a little more powerful.

On the "critical" list:

(1) Boards should be interconnected via ribbon cables to facilitate future repairs.  Display also needs to be entirely removable.

(2) Much of the display wiring needs to be rerun and shielded to prevent future breakage of LED leads

(3) Diagnose and fix current execution issues

Cosmetic:

(1) I'm thinking about building a card-cage to hold the individual boards so that they can be pushed in and removed similar to how one does with RAM in a motherboard or a card in a PCI slot.  This would cover number (1) on the "critical" list as well.  You can see an example of a card cage at http://homebrewcpu.com/Pictures/cage_1.jpg.

(2) Build an actual enclosure.  This is largely for appearance, but also to keep out dust and curious cats with whom I share a living space (who are also perhaps the source of the current issues the Kino 74 is experiencing, but who knows...).  The front panel would then also actually become a front panel meaning I would move it to the front of whatever enclosure I built.

Possible (however somewhat unlikely) upgrades and improvements:

(1) Move everything off breadboards to more permanent perf board.

(2) Communication/programming via a modern computer over serial/usb.

(3) Default program dumped into RAM at startup via EEPROM or something.

(4) Adding JMP (jump) and STR (store) instructions.

(5) Easier programming (currently have to get the thing into Timing state 2, flip three separate switches two of which are on the back of the computer, then toggle in all addresses and instructions in binary)

Discussion:

The stuff that is definitely going to get done is everything on the "critical" list and likely the development of some sort of enclosure and card cage (even if not a true card cage but more like a fancy shelf for the breadboards).  This stuff is the only way I can see the Kino 74 being able to continue functioning into the future, which is very important to me.

Everything else is an "if" and a "maybe".

A lot of these "ifs" and "maybes" are weirdly integrated with one another and arguments can be made in all directions.  I DO want to avoid falling into a huge amount of "might as wells" (e.g. "while I've got the engine out, might as well replace the exhaust system and drive train...") but at the same time I definitely want to make the thing a little more usable and pretty.

Ultimately it boils down to two questions in my mind: (1) how much am I willing to change about my original design and (2) how feasible are the bigger changes (mainly monetarily-speaking)? 

For instance moving everything off breadboards onto a set of standard-sized perf boards would make building or finding a card cage significantly easier as well as reduce the size and weight of the project.  It would likely allow for the addition of the EEPROM and additional control circuitry needed to implement jump and store instructions and finally would also be easier to add ribbon cable connectors to the boards at that point and well as develop a system of communication between the Kino 74 and a modern-day laptop via some sort of serial communication.

However, the Kino 74 would be a different computer and while I'm not terribly attached to the current implementation, I think there's something to be said for keeping my first major electronics project kind of as-is.  Also the cost, both monetary and time, would be significant when I instead could be putting that into a new much more capable digital electronics project.  I can't really add enough circuitry to actually make the Kino 74 capable of doing much more than it currently does so would adding the jump and store instructions really be worth it?  Finally, there is also the challenge of it being very difficult to find affordable wire-wrap boards meaning that soldering would likely be the cheapest/best options which... woo boy. That'd be a lot of soldering.

Paring down and only doing a few of the options doesn't really make a ton of sense to me either.  If I'm going to pull all the chips off the boards and rewire the whole thing on perf boards, then it does make sense to consider expanding the Kino a bit to make programming a little more interesting and educational as well as make the usability improvements.

I sort of feel like it's a little bit all or nothing on the "improvements" list with the exception of adding the new instructions; that I could easily leave off. We'll see what I decide though.

Conclusions:

There's a lot to think about and I don't have any great answers right now.  I think I'll gain a lot more insight into how I'm feeling once I pull the boards apart and see how things are looking.  I'll probably play around with laying things out on some different-sized perf boards and price out how much new parts would cost (mainly just sockets for all of the chips and possible upgrading the pairs of 4-bit register chips to single 8-bit register chips).

In the coming weeks I'm going to more carefully evaluate and price out the stuff on the "critical" list (mainly just adding all of the ribbon cables and connectors) and see where we are.  I may go ahead and start pulling things apart because it's somewhat hard to get a sense of just how the boards are interconnected (my schematics don't really exactly tell the details of how I wired everything).

I do seem to remember those breadboards being preeetty full without a whole room for new circuitry so it could be that to do anything will require a fair bit of redesign.  Then we're really down the rabbit hole.

Well, I already kind of am anyways with this damn project.

<3,
John

Update on Sister Shelf to Beth's

Hello anxiety, old friend.

Kind of a rough Saturday, friends.  To try and not dwell on that, I'm going to write about the project I was working on before the insane noise complaint the other day.  The sister-shelf to Beth's that I just finished a little bit ago.

After building Beth's bookshelf, I had some wood from the slab top left over.  Realizing also that I was really quite pleased with how her shelf came out, I figured "well now I kinda want one."  I also don't currently own any shelving of any sort; just some stacked old farm crates and a table I made to substitute for a headboard.  

I wanted this new shelf to be similar (i.e. draw from the same inspiration/sources) but be quite distinct from what she has.  They should be a pair, but not the same.  I knew that I wanted the wood choices to be the same since the maple/pear combination worked so well, although I will confess that I did not seek out any natural birch to accidentally "substitute" in certain spots.  I also needed this to be a little less labor-intensive than Beth's.  Haha. It's tough to convey the number of hours that went into that shelf.  Finally, it would have to be smaller because I simply didn't have as much wood and also don't have really any space currently for something the size of what I built her. 

What I settled on was two shelves, with a cantilevered slab top supported by a big chunk of cherry I had left over from my (still ongoing) chair project.  It's a weird design.  Weird enough that I probably wouldn't build it for someone else, but when I'm playing around with my own money and supplies to build something for myself, I can afford, and WANT to take a few risks I may not otherwise explore. 

Angled sides on the through-mortises.

I kept the radiating lines in the joinery, but instead of wedges, I actually shaped the through-mortises differently.  I also DRASTICALLY cut down the number of through mortises.  The bottom shelf only has one on each side and the upper shelf has two on each side.  While the shape made things a little interesting to chop, it wasn't too terribly difficult, and kept the "spirit" of the joinery the same as Beth's.

Shaping the slab using a Lancelot angle-grinder attachment.

Layout on a slab with no straight edges gets somewhat complicated.

Did I mention layout gets complicated?

One more of layout.

The angled edges of the mortised prior to cutting.

The slab top is joined to the base using some big old mortise and tenon joints, much the same as Beth's and I've started placing the dovetail keys with the same combination of maple and koa however it was in this process that I had to stop doing woodworking in the apartment.  This is really the last major step prior to finishing everything and doing the final glue up of all the different pieces.  Finishing is no small task, but I think it's reasonably quiet relative to everything else and I could probably do it in the apartment without anyone getting upset.  It has been nice having the loft be pretty clean though.  *Sigh* I neeeeed a workshoooop.  Ughhh.

Anyways, this is where it currently stands:

So friggin' close! Construction-wise all that's left is to reshape the cherry support in the middle to be a little less blocky and then finish setting the dovetail keys.

After that it's finishing everything (sanding, then applying finish) and final assembly.  I'm really pleased with how weird it is and how it's coming out.   One day, hopefully soon, it'll be finished. 

Hope everyone is having a good Saturday!

<3,
John

Doodle Dump

Minimal energy for a real post tonight.  I also pulled the "nuclear" noise complaint I had been afraid of and can't do any more woodworking in the apartment so haven't had that vehicle for stress relief lately.  I'm only now realizing how important that has become!

Instead of wood working I've been doing a little more reading (largely about programming) and drawing.  I've been fluctuating between really liking and really loathing the stuff that I've been doodling at work lately.  This is just a big old collection of all of it.

Enjoy. :-)

<3,

John

Sketchy sketch sketch

It's been a while since I posted much new artwork.  As I've been drawing more, I've realized how, well, not great I am at it? Haha.  Funny how that works, isn't it?    I have a bunch of hard-copy stuff I need to scan and post, but that's a lot of work, so for tonight, here are some doodles from my recently acquired iPad Pro done while watching MacGyver tonight.

image.jpg

It's also interesting how, you know, warming up actually makes a difference! I've numbered the sketches in the order that I did them and the 6 and 8 are by far the most natural and don't look totally screwed up if I flipped the canvas. I didn't really do a construction for 7 so probably shouldn't count that one so much. 

Anyways, early night tonight.  Hope everyone is doing well. 

 <3,

John

Another day, another shooting

There have been shootings now at both of the universities I have attended.  I enrolled at Virginia Tech four months after a student decided it was his place to take the lives of 32 other students, and today I waited on lockdown in my office for text updates about a student who, apparently despondent over a grade (a fucking grade), decided he had a right to kill his professor and then himself.  I watched, even before the lockdown of my building had been cleared, as the Internet lit up with the same old tired "debates" that it usually does.  All I could think was just "can we... not?"

I feel a little defeated these days: I actually support people's rights to own guns and I support people's right to carry guns in private and in public.  I am fairly liberal. I think it should be difficult to get a gun.  Guns are not made to not kill things, it is in fact their sole purpose.  In all other aspects of our society, we do not let unqualified people handle such responsibility.

Truthfully, I actually don't care about that argument tonight though.  Two people are dead who shouldn't be.  People often die in the streets a few miles from where I live who never needed to.  Maybe it all would've happened anyway, guns or not, but as a country a loud, vocal, insane few made our beds for us and it's time for the rest of us to sleep in it. We get to sit back and watch as the body count climbs, and look over our shoulders as we walk to class, church, home, the corner store, a concert, or maybe to elementary school.

As we do all that we can watch the political battle unfold to nowhere, again... and again.  We can watch the dead be held up and paraded around as mascots for what should or should not have been done, and strip them of identity beyond their roles in agendas and political battles. We can watch as an important argument turns into a yelling match funded by rich backers on both sides with no room for the rest of us.  

But maybe let's just save all that for tomorrow, and let the blood and tears dry tonight.