Reimplementing an Apple ][+ on an FPGA

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The… first… successful… Oh for Flying Spaghetti Monster’s sake.

1977's Apple ][+ was the first successful personal computer

Technically, the Apple ][+ was from 1979. The original Apple ][ was from 1977. They were very similar machines, the main difference was that Wozniak’s “Integer Basic” was replaced by Microsoft’s “Applesoft Basic”.

ugh, VHDL. probably 90% of chips are written in verilog… the other 10% being coded by kids in universities and overseas where for some reason they took the DoD seriously and adopted VHDL. universities i can understand; darpa grants and whatnot, but i don’t get the europe thing.

With VHDL, the compiler finds your mistakes.

With Verilog, the customer finds your mistakes.


yeah that’s funny, but with VHDL the customer also finds synopsys’ mistakes… there’s more than enough rope in VHDL to hang you, the compiler, and the customer. there’s just not enough VHDL out there to really pipeclean the toolchain. for us, every tapeout brought a new set of compiler bugs with each successive patch for bug n-1.

also, running Formality on abstract VHDL designs is a royal pain in the ass… never could be sure if the bug was in the compiler or the formal verification tool.

whatever abstractions people love so much in VHDL for testbenches are readily found in system verilog these days.

The Apple II+ (like the original Apple II), was based on a MOS 6502.

Have you seen Eric Schlaepfer’s recreation of the 6502 out of discrete transistors, built in collaboration with Evil Mad Scientist Labs?

The processor by itself doesn’t do much (apart from blinking lights when it runs), so they made a “minicomputer” based on an STM32 to serve as the “rest of the hardware” so that you can actually run something useful with it. The STM32 implements (in software) other features you’d expect from a 6502-era computer hardware, such as a sprite(blitting) engine and sound generation. And Eric programmed a small game for it:

I find it delicious that the STM32 is “support” for the 6502, a bit like having a combine harverster pulled by a mule :slight_smile:


That’s the story people want today, so no need to get bogged down in the details of the tedious past.

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This was my first computer hack.

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