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FPGA Cosmac ELF

A re-creation of a Cosmic ELF computer, Coded in SpinalHDL

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This is a re-creation of a Cosmac ELF computer, Coded in SpinalHDL.

The goal of this project is to end up with a cycle-accurate 1802 processor that can be used in FPGA designs easily.
When I start the project I was new to SpinalHDL but I had attempted in the past to write the same processor in VHDL. However, language complexity and the sheer amount of code and time needed to write and debug that project ended the work on it.

I have put a lot of the details about the project in the Github readme.

  • Finished Interrupt Handling

    Winston Lowe2 days ago 0 comments

    The 1802 CPU now supports Interrupt handling.

    Also added to the Cosmac Elf system supports for reading the serial RX, and it will set the interrupt flag when it's FIFO has data. You can use INP N1 to get bytes from the FIFO and check if it has data with BN2.

    I also have the write button set the interrupt flag, and using BN4 you can check the state of it.

    Here's a picture of the output of the terminal, for a little program I made to test the functionality. 

    When you press the Write button it send you the current byte of the data switches in hex. "Button: 00"

    And when you type on the terminal it stores the byte in a string buffer and when you hit enter it sends that buffer back to you. "Got: testing"

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ostropest wrote 2 days ago point

very nice

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Winston Lowe wrote 2 days ago point

Thanks

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Dan Julio wrote 3 days ago point

Very nice Winston.  I had the $99 Quest Elf in high school.  It was my first computer as well and I've always had a soft spot in my heart for the slightly quirky 1802.  Now you just have to add the 1861! :-)

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Winston Lowe wrote 2 days ago point

I'm think about make the 1861 at some point, now that I have the processor.

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Dan Maloney wrote 4 days ago point

Pretty cool. I had an RCA COSMAC VIP in high school. It was my first real computer. This makes me think about using my Superconference FPGA badge to make a VIP of my own.

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Winston Lowe wrote 2 days ago point

That would be super cool

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