Nathan's build log.

N8VEM: Minor issues

thomasns — Mon, 25 Jan 2010 14:05:34 +0000

Hey everyone, I know it’s been awhile since I posted any news. Blame it on school starting back. Anyway, since December, I’ve made little progress on the N8VEM. The board is finished, and all the chips are in save two. This is because of a few problems I’ve had.

A) I ordered the 2.5MHZ Z-80 but a 4.0 Oscillator

B) One of my chips is the wrong logic family.

As soon as I get some money to order from jameco, and some time, I’ll make an order and get some more picutres up.

In the mean time, I’ve started another Z80 project, Elvira. This one is lacking most of the bells and whistles of the N8VEM, but it has blinkenlights. More info soon.

N8VEM: Initial Soldering.

thomasns — Mon, 21 Dec 2009 02:23:38 +0000

After finals and some issues with snow and power loss I finally started soldering. I’m going from lowest profile components and moving up to make soldering easier. I’m still missing a single socket and an EPROM burner, but other than that all my parts are in order.

This is our work area, set up in my sisters old bedroom.

This is the board after I soldered the resistors on to the board.

The board after adding all but one of the sockets. The mill-max sockets, such as the ones in the center of the board, are slightly lower than the cheaper sockets, so I had to solder them first and follow up with the other style. While the mill-max sockets are nice looking and slightly sturdier, the cheaper sockets are much easier to solder and sturdy enough for the N8VEM in my opinion.

Finally, I added a few smaller componets and the S-100 bus connector.

Only 10 of the capacitors are installed so far. I’m planing on soldering the rest of the caps tonight, and the rest of the parts tomorrow. The only real difficulty so far has been holding some of the looser parts steady while soldering.

Still alive.

thomasns — Mon, 30 Nov 2009 19:46:23 +0000

Just a quick apology for the lack of news. In theory the remaining parts are waiting for me at my house. I doubt I’ll get much done in the next few weeks due to finals. When Christmas hits, I’ll take a few days to solder the computer up and post lots of goodies. Hopefully I can get an actual VT-100 or a pocketterm before it’s ready.

N8VEM: PCB Unboxing

thomasns — Wed, 04 Nov 2009 17:24:08 +0000

My PCBs came in today.My first impression was that they were a bit smaller than expected, but that is a bit of a good thing. Size aside, the board is very well designed. The board is labeled well, and easy to read. Also, the parts are laid out to were soldering at least appears to be easy enough.

After I finished looking at the board, I decided to pop some of the ICs in just to get a feel for what it should look like finished. I’m still waiting for a few shipments of student samples to arrive before I order the remaining parts, but this gives a good impression. One note though, most IC legs come bent at a slight angle, but the board is designed for straight legs. I would recommend using one of the plug in sockets to straighten the legs before attempting to put them in the PCB. I mangled a few pins before I figured out this trick.

N8VEM: Pictures

thomasns — Wed, 04 Nov 2009 17:10:22 +0000

As promised, here are some pictures of my part testing.

First, is my generic testing set-up. The breadboard on the left is simply a byte created with LEDs (ignore the SRAM in the background). The breadboard has the IC I’m currently testing hooked up to an SX microcontroller. The microcontroller is very useful for controlling the values being input into the IC and for regulating the power. The output pins on the IC are jumped to the LEDs as well as the ground completing the circuit.

Here is the same setup, while running. It’ s hard to tell which LEDs are on in the picture but when it looks much better in person.

All things considered this setup is very useful for showing how something works. I had trouble at times due to a lack of wires but other than that it worked as well as could be expected.

N8VEM: Parts

thomasns — Mon, 02 Nov 2009 03:26:29 +0000

While waiting for the remainder of my parts to get here, I’ve been going over the data sheets for the parts, the Texas Instruments parts in specific. So far everything has went as expected, sans me realizing the sram doesn’t quite have the juice to drive 8 LEDs, which was more of my stupidity than anything. I’m going to post some pictures as soon as possible, including my rather embarrassing collection of packaging materials (so far, TI wins in speed of delivery, Mil-Max gets the best box award, and Intersil for most insanely protective packaging and QMIrep gets the award for pretty much most helpful company ever).

Thats all for now, I’ll post pictures as soon as I get a camera better than my phone.

First Project: N8VEM Single Board Computer

thomasns — Mon, 26 Oct 2009 02:24:04 +0000

In truth, this was my main reason for starting this blog. The n8vem is an old school Z80 based computer running CP/M designed to be easy for relative beginners to build. Using easy to get dual in-line package (DIP) components and designed for easy soldering and testing. I’ve built plenty of computers before, but with modern computers you hardly learn anything by plugging a video card into a motherboard. I’m hoping to use this project to learn exactly what happens when the a signal goes into a specific IC chip on the computer, and where it goes from there. The whole thing can be put together for a little over $100.

The first step in the build process is to get the parts. The printed circut board can be ordered directly for $20. But the rest of the parts have to be ordered from outsider distributors; parts list can be obtained from the N8VEM website.

Most of my parts are on the way, so I’m waiting for the last few shipments of parts to get here before I start.

Until all the parts arrive, I’m taking each IC and using my SX micro controller to study how the chip interacts with different conditions, but I won’t babble about that unless something particular pops up.

FurtherReading;

Hello world!

thomasns — Mon, 26 Oct 2009 01:14:17 +0000

Hello all!

This isn’t intended to be a “blog” in the usual sense. It’s mostly intended as a build log of my various projects as i go through out my life.

So, I’ll be updating as I go along.