BigEd wrote:
A build log is a great idea, and I think it be fine as a continuation of this thread. It's nice if, when you have particular questions, you start a well-focussed thread on each question.
Thank you, I will proceed this way!
GaBuZoMeu wrote:
Just a question: how do you plan to get your baby up and running?
You concerns are more than justified
The way I believe I'm going to "baby-step" my circuit is by first ignoring the video section entirely. I have already built a simple breadboard 6502 computer so the first thing I will do is basically copy what I have already done setting up the CPU, RAM, ROM, and VIA, with the added complexity of the address multiplexers in between. I will first use an Arduino to provide a very slow clock (even single step at first) to use an array of LEDs to inspect the address and data busses, then I will setup a serial communication between the circuit and my desktop computer to use my very simple OS. Then I will set up the video generation circuit with a minimal char ROM and I will make sure that the composite video signal is correct, using Arduino as ADC (still running at very low speeds naturally).
When everything is operating correctly, I will connect the 8MHz oscillator and test the system with a composite to VGA adapter, which I already used to test some experimental composite signals with Arduino.
It is a long way to go!
I already have a constructive question. I am totally new to wire wrapping, and I have never used it before. I went online to look for some WW sockets and I indeed found them to be quite expensive, particularly on big resellers. I went to Ebay with little luck, particularly with Italian sellers. Even 6 euros for a 14 pin socket
I found significantly cheaper sockets on UK Ebay, sold in 32 pins strips. The picture was not very clear, but they were sold as WW sockets and the dimensions matched the WW tool I got, so I bought them. Sadly, it turns out that the pins have a round section, not a square one as usually described in guides and online reference. To be honest, I was afraid of that from the picture, but since I never found round pins mentioned in online guides, I assumed I was wrong,
I have tried wrapping 30AWG wire on the pins with my tool, but the bond is terrible. A very small pull on the wire causes it to unwrap and the whole wrapping can easily slide along the pin.
I assumed the pins were unusable, then I realized I could get them to be a bit more "square" by lightly sanding down two faces with fine grit sanding paper. Since the strips have many pins, it is quite easy to sand them as shown in the attached picture, removing the red parts. I know that probably the bond at the edges will not be as good as what I could get with a proper pin, however now the wraps are so strong that the wire will snap before the wire starts unwrapping, and I can't get the wrap to slide along the pin. Do you believe this will be good enough to get a good electrical connection? Keep in mind I'm not looking something that will last many years, as I'm planning to make a PCB for the circuit and reuse the sockets for future projects.
Thank you for your help!
Kind regards,
Davide