From the monthly archives: April 2012
I just finished wiring up the NVRAM chips to the computer. They are being addressed by a 8-bit program counter separate from the computer’s control counter. The control matrix changes its control word on the falling edge of the clock pulse. This allows the control to set up the 16-bit word, needed to tell which […]
For the control matrix of my computer I am using some NVRAM chips to store a 16-bit control word for the various registers and control wires of my CPU. I decided not to use EEPROM as the chips that I bought were all faulty and wouldn’t write (I consulted many people and they agreed). I […]
I finished the microinstructions for the control matrix of my computer. The block diagram on the upper left is the architecture of the computer itself. The chart below it is a list of OP codes for different macroinstructions. The chart on the right is the list of each individual microinstruction that makes up each macroinstruction.
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After a month I finally received my breadboards from China and can start finishing the breadboard work on my computer. I now have all of the registers constructed as well as the ALU. Everything is connected to a data bus (bottom) that allows for the transfer of data from one register on the computer to […]
A CPU consists mainly of registers (places to store values) that have to be controlled by, you guessed it, a control matrix. The control matrix outputs a control word, CON, whose bits activate the needed registers on a computer for input and output. For my computer I am using 3 NVRAM chips to store all […]
For the display I wanted something more interesting than a simple binary readout. I decided to go with the retro look and use some IV-9 russian Numitron tubes that can be conveniently driven by 5V with 20mA of current, the perfect amount to use a 4511 7-segment decoder. The only problem in the way of […]
Without the textbook Digital Computer Electronics by Albert Malvino I wouldn’t have been able to even start this project. If you are considering building, or even learning about a computer using TTL this book is extremely worth the small amount of money you have to pay for it on Amazon. The TTL Cookbook by […]
The first parts that I purchased for my computer included two breadboards and the logic chips to build a simple Arithmetic Logic Unit that could preform addition and subtraction on 4 bits. Initially I was going to build a 4 bit computer, but I later decided that having a computer that could only operate with […]
