Specification
Features
This is a list of features I aim to include in Tiny Tim, based on the previous research:
Clock speed: ~200 KHz
Memory: 8 Kilobytes of SRAM, split into two 4 Kilobyte sections
Registers: Working Register (8 bit), Instruction Register (8 bit) , Address Register (12 bit), Program Counter (12 bit), 16x Zero Page Registers (8 bit)
Power supply: 5V at 2 Amps (peak). May include variable voltage supply for over clocking.
Input: Tape reader to input programs. Dip switches to input data, keyboard may be added later
Output: LED's on front panel for debugging, Small LCD Ascii Display for data
This is the approximate layout so far.
I have decided that the boards will be stacked one on top of the other and then bolted together. The boards I plan to use are shown here. To connect the boards there will be a plug on both sides of the board. The plug layout will be the same on each board, so it won't matter in which order the board are connected. Below is a rough illustration of how it might look. I'm predicting the whole computer will use about 7 or 8 boards depending on how closely I can pack the components.
Parts
I have just received a large proportion of the 2700 components required to build Tiny Tim (CPC didn't have enough stock to complete the order, so the rest of the parts should be ariving in a month or so). EDIT: All parts have now arrived, but only the first 2000 or so are depicted below.
During my research, I tried to work out component values that balanced price with computer speed. The components I have ordered are:
1300 BAT 42 Schottky Diodes
400 2N3904 NPN Transistors
400 1K 0.125W Resistors
400 100K 0.125W Resistors
100 100nF Capacitors (for voltage rail smoothing)
7 RE200-HP Prototype Boards
I haven't yet ordered the memory chip (I forgot) so that will be ordered when needed.