Building up disk tool foundational logic

The Digital Game Museum has a policy that a board member must be in attendance on each Saturday, when we are open to the public. It was my turn to be there today. It was very quiet.

XEROX ALTO - DIABLO DISK TOOL CREATION

I rolled in the code from the Digilent reference implementations to allow PC users to read or load the DRAM on the fpga board, as well as writing or reading from eight registers I defined in the FPGA. These will be used to request transactions such as 'read a sector into the DRAM'.

That is all cleanly synthesizing, It does need to be tested just to verify that the PC can talk to the fpga board, and that stored information comes back as written.

It is my intent to test the extension board with the current hookup of the switches, buttons and LEDs then when I am sure that all the connectivity is correct, I can reassign these to display the registers and other system state of the tool.

I put in logic to drive the four digits of seven-segment displays, which will show selected information while the board is in operation. For example, it can display the current cylinder number, the current head and sector number, the current command, the response and the status of the last operation.