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+#+TITLE: Prototype 2
+#+DATE: <2021-03-03>
+#+SETUPFILE: ../../options.org
+
+#+BEGIN_COMMENT
+m4_define(`_REL_HEADER', `Next: <ahref="/z80/prototype1.html">Prototype 1</a> Up: <a href="/z80/">Z80</a>')m4_dnl
+#+END_COMMENT
+
+{{{date_place(Bremen, Germany)}}}
+
+#+CAPTION: Prototype 2
+[[https://thomaslabs.org/media/prototype2_1.jpg]]
+
+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
+
+#+CAPTION: Prototype 2 together with screen
+[[https://thomaslabs.org/media/prototype2_2.jpg]]
+
+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.