Saturday: Vintage Computer Festival West

The Vintage Computer Festival West is an annual gathering to celebrate the awesome hardware that ushered in the Information Age. Normally held at the Computer History Museum in Mountain View, California, this year VCF West is happening virtually and it all starts on Saturday!

The lineup of talks looks great, covering everything from operating an Apollo DSKY display panel and how to recover magnetic tape to ENIAC technical manual bugs and the genesis of the 6502. That last one is presented by Bill Mensch who was on the team that created the 6502 in the first place. He’ll be joined by Hackaday’s own Bil Herd (himself a celebrated Commodore and MOS alum) and Eric Schlaepfer (you may remember his Monster 6502 project). You may not be able to wander the exhibits and play with the vintage hardware this year, but you can hear from a lot of people who have spent years learning the hacks and quirks that made these systems tick.

Hacakaday is proud to once again sponsor VCF West. You don’t need a ticket, the conference will live stream on their YouTube channel for all who are interested. We’ve embedded the live stream below, as well as the awesome poster at that Joe Kim produced for display at the festival.

Continue reading “Saturday: Vintage Computer Festival West”

Die Photos Reveal Logic From Commodore 128 PLA Chip

The 8721 PLA, or programmable logic array, was one of the chips that had to be invented to make the Commodore 128, the last of the 8-bit computers that formed the leading edge of the early PC revolution, a reality. [Johan Grip] got a hold of one of these chips and decided to reverse engineer it, to see what the C-128 designers had in mind back in mid-1980s.

PLAs were the FPGAs of the day, with arrays of AND gates and OR gates that could be connected into complex logic circuits. [Johan]’s investigation started with liberating the 8721 die from its package, for which he used the quick and easy method favored by [CuriousMarc]. The next step was tooling up, as the microscope he was using proved insufficient to the task. Even with a better microscope in hand, [Johan] still found the need to tweak it, adding one of the new high-quality Raspberry Pi cameras and motorizing the stage with some stepper motors and a CNC controller board.

With optics sorted out, he was able to identify all the pads on the die and to find the main gate array areas. Zooming in a little further, he was able to see the connections between the matrices of the AND and OR gates, which makes decoding the logic a relative snap, although the presence of what appears to be an output block with latching functions confounds this somewhat.

The end result is a full Verilog HDL file that reflects the original 8721 logic, which we think is a pretty neat trick. And we’d love it if our own [Bil Herd] could chime in on this; after all, he literally designed the C-128.

Video: Bil Herds Looks At Mitosis

I loved my science courses when I was in Junior High School; we leaned to make batteries, how molecules combine to form the world we see around us, and basically I got a picture of where we stood in the  scheme of things, though Quarks had yet to be discovered at the time.

In talking with my son I found out that there wasn’t much budget for Science learning materials in his school system like we had back in my day, he had done very little practical hands-on experiments that I remember so fondly. One of those experiments was to look and draw the stages of mitosis as seen under a Microscope. This was amazing to me back in the day, and cemented the wonder of seeing cell division into my memory to this day, much like when I saw the shadow of one of Jupiter’s moons with my own eyes!

Now I have to stop and tell you that I am not normal, or at least was not considered to be a typical young’un growing up near a river in rural Indiana in the 60’s. I had my own microscope; it quite simply was my pride and joy. I had gotten it while I was in the first or second grade as a present and I loved the thing. It was just horrible to use in its later years as lens displaced, the focus rack became looser if that was possible, and dirt accumulated on the internal lens; and yet I loved it and still have it to this day! As I write this, I realize that it’s the oldest thing that I own. (that and the book that came with it).

Today we have better tools and they’re pretty easy to come by. I want to encourage you to do some science with them. (Don’t just look at your solder joints!) Check out the video about seeing mitosis of onion cells through the microscope, then join me below for more on the topic!

Continue reading “Video: Bil Herds Looks At Mitosis”

High-Speed PCB Design Hack Chat With Bil Herd

Join us on Wednesday, September 25 at noon Pacific for the High-Speed PCB Design Hack Chat with Bil Herd!

Printed circuits have become so commoditized that we seldom think much about design details. EDA software makes it easy to forget about the subtleties and nuances that make themselves painfully obvious once your design comes back from the fab and doesn’t work quite the way you thought it would.

PCB design only gets more difficult the faster your circuit needs to go, and that’s where a depth of practical design experience can come in handy. Bil Herd, the legendary design engineer who worked on the Commodore C128 and Plus4/264 computers and many designs since then, knows a thing or two in this space, and he’s going to stop by the Hack Chat to talk about it. This is your chance to pick the brain of someone with a wealth of real-world experience in high-speed PCB design. Come along to find out what kind of design mistakes are waiting to make your day miserable, and which ones can be safely ignored. Spoiler alert: square corners probably don’t matter.

join-hack-chatOur Hack Chats are live community events in the Hack Chat group messaging. This week we’ll be sitting down on Wednesday, September 25 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about. Continue reading “High-Speed PCB Design Hack Chat With Bil Herd”

Video: Putting High Speed PCB Design To The Test

Designing circuit boards for high speed applications requires special considerations. This you already know, but what exactly do you need to do differently from common board layout? Building on where I left off discussing impedance in 2 layer Printed Circuit Board (PCB) designs, I wanted to start talking about high speed design techniques as they relate to PCBs.  This is the world of multi-layer PCBs and where the impedance of both the Power Delivery Network (PDN) and the integrity of the signals themselves (Signal Integrity or SI) become very important factors.

I put together a few board designs to test out different situations that affect high speed signals. You’ve likely heard of vias and traces laid out at right angles having an impact. But have you considered how the glass fabric weave in the board itself impacts a design? In this video I grabbed some of my fanciest test equipment and put these design assumptions to the test. Have a look and then join me after the break for more details on what went into this!

Continue reading “Video: Putting High Speed PCB Design To The Test”

Inductance In PCB Layout: The Good, The Bad, And The Fugly

When current flows through a conductor it becomes an inductor, when there is an inductor there is an electromagnetic field (EM). This can cause a variety of issues during PCB layout if you don’t plan properly, and sometimes we get burned even when we think we have planned for unwanted inductance and the effects that come with them.

When doing high speed logic we need to be able to deliver sudden changes in current to the devices if we want to have proper switching times and logic levels. Unfortunately inductance is usually not a friend in these circumstances as it resists those sudden changes in current. If the high speed devices are driving capacitive loads, which themselves are resisting changes in voltage, even more instantaneous current is needed.

Simply put, inductors resist a change of current, and can act as a low pass filter when in series with the signal or power supply flow. Inductors do this by storing energy in the flux surrounding the conductor. Alternatively capacitors resist a change in voltage (again by storing energy) and can act as a high pass filter when in series with the signal. This makes them a valuable tool in the fight against unwanted inductance in power supply distribution.

In the video below, and the remainder of this article, I’m going to dive into the concept of inductance and how it affects our design choices when laying out circuit boards.

Continue reading “Inductance In PCB Layout: The Good, The Bad, And The Fugly”

How To Do Beautiful Enclosures With Custom Fiberglass

There are times when I feel the need to really make a mess. When I think of making messes with a degree of permanency, I think of fiberglass. I also really like the smell, reminds me of a simpler time in 8th grade shop class. But the whole process, including the mess, is worth it for the amazing shapes you can produce for speaker pods and custom enclosures.

Utilizing fiberglass for something like a custom speaker pod for a car is not difficult, but it does tend to be tedious when it comes to the finishing stages. If you have ever done bodywork on a car you know what kind of mess and effort I am talking about. In the video below, I make a simple speaker pod meant for mounting a speaker to the surface of something like a car door.

You can also use a combination of wood and fiberglass to make subwoofer cabinets that are molded to the area around them. You can even replace your entire door panel with a slick custom shaped one with built in speakers  if you’re feeling adventuresome.

Continue reading “How To Do Beautiful Enclosures With Custom Fiberglass”