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Greetings Programs,

You may have noticed (or not!) that I've been less active here than usual for the past few months. That's because Victoria got a new job and we moved to Texas!

Our new house has an outbuilding in the back yard, which our landlady has given me permission to finish and turn into a workshop. This is a fairly pricey project, however, since the outbuilding is totally unfinished and not climate controlled, so I'm saving that for the fall. In the meantime, I've converted a corner of the garage into a makeshift workshop and partially unpacked my tools and supplies. This week I'm home sick for my birthday ( ) and I felt like working on a project. Maybe surprisingly, I've never actually built a whole breadboard computer, so I decided to do that. I started out with baby steps. Good news! My DMM still works; my scope still works; I still remember how to cut jumper wires! I whipped up a partial schematic: Not much new in here; it's mostly using simpler versions of ideas from Blue August. It will have a VIA in case I want some output ports, etc., but I'm mostly planning on connecting to it with a serial terminal over an ACIA. I laid the parts out on my breadboard: But there's a twist! I will be using the "wire wrap on breadboards" construction method! Why? No particular reason, except it seems like a neat idea. A retro-computer enthusiast on another forum used this method to give a little more permanence to a very elaborate breadboard system he built. I wired up the power LED and clock generator today (I said baby steps, right?): So far so good! Getting a nice clean 4MHz signal out of my 74HC74 flip-flop.

Welcome to Texas! Be sure to stop by sometime and we'll get some BBQ and watch some bats.




Curious, why add sockets to the bed board instead of plugging the components directly in?

Partly for tidiness in some cases, but mainly to get good connections. The tactile switch and the DS1813 in the upper left, for example, are loose if you plug them directly into the breadboards. The switch's legs are too short, and the DS1813's legs are too skinny! Some of the ICs are also in sockets, but that's just because they were already in sockets and I didn't bother taking them out (the CPU, for example).

Wired up the control signals this evening: I changed the design a little, too: I have a couple of 32Kx8 "wide" Hitachi SRAMs that I thought would be fun to use for this project. I got them in my very first "electronics workshop" order to be spares for Blue April, but never needed them. But then I was thinking about all the extra bus wiring, and just went ahead and put in one of m 64Kx8 "skinny" SRAMs. Saves breadboard real-estate, reduces wiring, *AND* it gives me the chance to try out one of the nifty `139 decoding schemes that Mike McLaren shared with me a while ago.

Can I ask, what the wire wrapping white wire is? (What diameter is the metal core?) Thank you

It's the Good Stuff - Jonard Tools 30AWG kynar wire wrapping wire. It's pretty expensive, but every so often the Jonard Amazon store will have this or that color on clearance, so I buy a big spool. https://www.amazon.com/gp/product/B006C ... =UTF8&th=1 I currently have white, black, and blue. The blue is my favorite to work with; it just seems to strip more easily than the other colors, and I get the best good wrap / bad wrap ratio with it. I'll do the address bus with the blue wire, because it has the most wraps. Data bus will be with the black wire.

Thank you very much

Yes, welcome to Texas! Depending on where you are in our great state, you might die from tornado, hurricane, drought, or cedar fever. Great time to be alive
LOL!

Anyways, glad you are back Paganini. I too have been absent for some time, and just decided to pop in and saw your post. Your project seems fun because of it's (current) simplicity. Interesting method of wire-wrap + breadboard, but if you like that then all the better.

Thanks for the updates!

Chad

Hi Chad, good to see you!
Yes, I didn't want anything too challenging, just now. Blue August is still in progress, but partly disassembled, and some of my workshop stuff is still packed. Plus, moving is stressful, and my dog died the day before the movers came to pack up the house (if I keep on like this I'll be sining a country song!) so I wanted something relaxing.

I'm actually really liking the wire-wrap + breadboard combination. It looks kind of strange at first, but it goes really fast. It's pretty similar to my protoboard construction method, except without any soldering.

Huh ... I mistakenly thought that conservative talk radio rants hadn't yet been invented when you were roaming the Earth. You should try switching to smooth jazz ... it's better for your blood pressure.

Although in the long run I suspect there are few views that BDD and I share... I agree about the smooth jazz! I just don't think that's what Schoenberg had in mind when he emancipated the dissonance.

Had a bit of a setback today; it seems like my DS1813 reset controller is broken. Any time it's plugged in RESET\ is held low. That was my last one (I only bought 5 because they're kind of expensive) so I had to rejigger that area of the board a bit to use Garth's reset circuit from the Primer. I didn't have the exact resistor values, but I got as close as I could (22k and 4.7k resistors, instead of 27k and 5.6k) but it *seems* to be working OK. I'll hope that my good old G65SC02 is forgiving.

It took me a minute to remember how the FX2 logic analyzer board works, but once I reread my own thread it came back pretty quickly. I put a header on the breadboard (you can see it down in the lower left near the VIA) so I can just plug the FX2 board in when I want to use it.

Anyway, the good part is, it worked first try! I haven't fully tested the build yet; I just put a NOP ROM in. But, I got a clean reset, read the reset vector ($8000) jumped to it, and started executing NOPs. So that means I didn't make any major wiring mistakes. I always feel really good when a project works right away and I don't have to do a lot of error hunting.

This is probably a good time to reiterate how much I like having Hoglet's decoder available for this kind of thing. I can immediately use it as a kind of makeshift output device; no messing around with LCDs or VIA LEDs. I can just plug in a little doodad and immediately see in detail if my board is doing what I told it to. It's a great resource!