« BackMOS tech 6502 8-bit microprocessor in pure SQL powered by Postgresgithub.comSubmitted by adunk 8 hours ago
  • eatonphil 37 minutes ago

    Very cool! If you want to see a much simpler version of this I wrote an article a few years implementing a stack language in Postgres PL/pgSQL similar to what this one does.

    https://notes.eatonphil.com/exploring-plpgsql-forth-like.htm...

    • Someone 4 hours ago

      This, basically, uses a table to store 64 kilobytes of memory, a single-row table for storing register values, and uses regular procedural programming to run the CPU (https://github.com/lasect/pg_6502/blob/main/init/05_execute....)

      I give that an A+ for perseverance, but I would have hoped to see something that uses the strengths of SQL more.

      For example, there could be a table with the decode ROM (https://www.cpcwiki.eu/index.php/MOS_6502#The_Decode_ROM_.28...) that could be used to drive the logic.

      Have a main loop that uses the inputs of that ROM to look up the output bits and update a table, and add triggers that handle each “micro-op”. A SQL engine could run those triggers in parallel until they hit a race condition, but those can be avoided a bit by having separate tables for each register.

      Even better would be if there were tables with every logic gate and wire in the original CPU, using a trigger to move the signals around. That would be a good test of the trigger handling in a SQL engine.

      • larodi 39 minutes ago

        Waiting for 6502 implemented on top of Sudoku!

        • m000 5 hours ago

          Cool! How about Postgres on MOS tech 6502 8-bit microprocessor powered by Microsoft's 6502 BASIC?

          • anthk 3 hours ago

            Kim-1 emulator and assembler for T3X0:

            https://t3x.org/t3x/0/sim65kit.html

            https://t3x.org/kimuno/

            Pocket calc as 6502 code

            https://t3x.org/kimuno/kimcalc.html

            T3x0 compiler to build the emulator:

            https://t3x.org/t3x/0/index.html

            I've got to run under OpenBSD/i386 but it needs a bit of tweaks in the Makefile. On the target section:

                # CFLAGS=$CFLAGS" -m32"                 # on x86 64-bit systems 
    CFLAGS=$CFLAGS" -static"                # in case all else fails
    CFLAGS=$CFLAGS" -fPIC"          # get rid of stupid linker errors
    CFLAGS=$CFLAGS" -Wl,-z,notext"  # get rid of stupid linker errors
    CFLAGS=$CFLAGS" -fno-PIE -no-pie"       # get rid of stupid linker errors
            Do the same in the bin/tx0.sh and bin/build.sh just in case. In my system I set the target to unix-386, and T3XDIR it's set to T3XDIR=/usr/local/t3x/lib in the Makefile and bin/tx0.sh scripts.

            Also, T3XBIN it's set to BINDIR= /usr/local/t3x/bin

            Then I ran:

                  sh bin/modpath.sh /usr/local/t3x/lib 
      gmake all-native
      doas gmake install-native install-modules
            But it was still broken. Then, I edited /usr/local/t3x/bin/tx0 and set

            TX3DIR is above, and ditto with the four CFLAGS flags I posted.

            Just the ones at lines 38-42.

            OFC set PATH to /usr/local/t3x0/bin:$PATH in ~/.profile:

                    export PATH=/usr/local/t3x0/bin:$PATH
            Yeah, it's tricky, but from now on everything will just compile with

                  'tx0 foo'
            where 'foo' it's a foo.t file.

            This was compiled under an Atom n270 CPU based netbook. I think the author uses a Pentium III machine. If T3X0 can do a MOS 6502 emulation that well, you can try expanding s65/sim65 to cover the Apple I emulation.

            And, as a plus, it might run fast on DOS 386 machines if s65/sim65 it's compiled a native binary.