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Follow up on my 8bit breadboard computer emulator, written in C++

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Follow up on my Breadboard8mini 8bit cpu emulator

This is an in-depth emulator of Ben Eater's 8 bit breadboard computer down to the micro instructions.

Build the project by running make, this creates a bb8 & eas executables using g++, as well as the rom.out image making use of numpy.

Run the emulator using ./bb8 <program file> <clock speed> [rom image]. rom image loads rom.out by default.

Screenshot

image

Editing the microcode

The makerom python script is based on Ben Eater's arduino EEPROM programmer. Edit the template to add instructions.
When changing the micro-instruction definitions make sure to edit both the python script and core/include/microcode.h.

Running python3 makerom.py outputs the rom image in rom.out, unless a different file is specified.

Writing your own program

See the readme file for assembler syntax. Run ./eas <source code> [output path] to assemble your code. If no output path is specified a a.out file will be created.

Test program

When the microcode contains no jump if carry, shiftleft.out outputs all zeros once a value greater than 128 is reached:

example of conditional jump not implemented

Meanwhile a working jump if carry will execute in a loop:

example of working jump carry