Thomas' Labs

Prototype 2

Bremen, Germany, March 03, 2021

Figure 1: Prototype 2

Because when moving to Bremen, I wasn't able to take my old Prototype with me, I had to build a new one. This time though, I needed something easily modifiable.

One of the disadvantages of my first Prototype, was the fact, that it took me around 3 days to build and, because it was soldered, it was difficult to modify. This made experimenting with new ideas somewhat impractical.

Prototype 2 would be a prototyping tool, as such, it had to be built with a technique, that allowed for the electrical stability of a soldered circuit, but with the flexibility of a breadboard.

This time I chose the wire wrap assembly technique, as it met all requirements.

The following is a list of what I was able to accomplish thanks to Prototype 2

  • New memory banking system that would allow it to handle up to 4 MiB of memory, instead of the default maximum of 64KiB.
  • Add a RTC
  • Add video capabilities using a 480x320 18-bit color display
  • Dual serial ports with complete modem control lines
Figure 2: Prototype 2 together with screen

It didn't take long until Prototype 2 became incapable of fulfilling its task. Once it was clear, which parts would definitely be part of the final design, the flexibility of wire wrapping was no longer needed. Added to this, the circuit experimented detrimental voltage drops, due to the length of wire used. It was now time to design a third prototype, this time using a PCB.