====== 4-Bit Computers ======

**Martin Sauter**

**This page is an example for how an exhibition in this wiki could look like. The Busch 2090 and the Nibbler won't be presented at VCFB 2020!**

===== My Virtual Exhibition Desk =====

You will find me and my devices at my virtual BBB exhibition desk [VIA THIS LINK - TO BE INSERTED] at the times indicated below. During those times I will give an overview of my projects. During the 'normal' presence times I will be available for questions, discussions and 'coffee talk'.

===== Demo Times =====

^ Day       ^ Time          ^  Demo          ^
|Saturday     | 2:00 pm  | Busch 2090 |
|Saturday     | 3:00 pm  | The Nibbler |
| | | |
|Sunday     | 11:00 am | Busch 2090 |
|Sunday     | 12:00 am | The Nibbler |


===== General Availability =====

^ Tag       ^ Uhrzeit          ^
|Saturday     | 10:00 am - 12:00 pm |
|Saturday     | 2:00 pm - 5:00 pm |
| | |
|Sunday     | 10:00 am - 1:00 pm |
|Sunday     | 3:00 pm - 5:00 pm |

===== How Does My Virtual Desk Work?  =====

Just use Chrome or Firefox and click on the link above to join me at my virtual desk. No software installation is required.

I will be available at the indicated times and can show additional images and background information. By using the 'screen sharing' function I can demonstrate the Raspberry-Pi emulation of a cassette recorder, which I use to transfer programs to and from the Busch 2090. Apart from that I will use this function to demonstrate the assembler and the simulator for the Nibbler.

In addition I will use a smartphone as a video camera to present my devices. The smartphone is mounted on a small tripod so I can move in closely and give live demos.


===== Busch 2090 - Date of Manufacture: 1981  =====

At the beginning of the 1980's 'experimental computers' and kits were very popular to introduce computing to teenagers and grown-ups alike. The Busch 2090 introduced in 1981 was one of those devices and was based on the TMS-1600, a 4-Bit CPU by Texas Instruments. This device will be shown together with a tape emulator and PC-Cross assembler. 4-Bit computers are ideal to understand the interaction between the arithmetic logic unit (ALU), the control unit (CU), registers, memory, etc., as the simplicity of a 4-bit architecture makes it easy to explore the system not only theoretically but also in practice.

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===== The Nibbler with a 1970's ALU =====

The second 4-Bit computer I will present is the "Nibbler". It is based on a 74181 ALU chip which has been used in legendary computers like the Date General Nova, the Xerox Alto, the PDP-11 and many other computers of the 1970's.

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