44 lines
2.4 KiB
Markdown
44 lines
2.4 KiB
Markdown
# pill\_6502: emulated 8-bit 6502 CPU and 6850 ACIA for STM32F103 blue pill
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[](https://circleci.com/gh/satoshinm/pill_6502)
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[6502](https://en.wikipedia.org/wiki/MOS_Technology_6502) 8-bit CPU and
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[6850](http://www.cpcwiki.eu/imgs/3/3f/MC6850.pdf) ACIA emulator for the
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[STM32F103](https://www.reddit.com/r/stm32f103/) [blue pill](http://wiki.stm32duino.com/index.php?title=Blue_Pill)
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microcontroller boards and similar. Turn your modern micro into a retrocomputing processor.
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To build, run `make`, to install, flash `src/pill_6502.bin` to the blue pill.
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Prebuilt binaries are available from [CircleCI](https://circleci.com/gh/satoshinm/pill_6502/).
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Connect the board to your computer using USB, this will reset the CPU
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and a virtual serial port should appear (e.g., `/dev/cu.usbmodem6502`),
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connect using GNU Screen, and you should see the output from the emulated
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ACIA communication interface chip. Type to send to the ACIA.
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Special commands built-in, not passed to the ACIA and 6502:
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| Keystroke | Action |
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| --------- | ------ |
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| ^V | Show `pill_6502` version |
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| ^P | Pause/resume 6502 processor execution |
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| ^R | Reset the 6502 processor (also reset on USB reset) |
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| ^E | Local echo toggle, off by default |
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| ^T | Show clock ticks, instruction count, and frequency since last ^T |
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| ^G | Show help |
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Intended to be somewhat compatible with [Grant Searle's Simple6502](http://searle.hostei.com/grant/6502/Simple6502.html),
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and includes the Microsoft OSI BASIC ROM by default (C) Microsoft 1977. Other ROMs can be loaded
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by replacing `ROM.HEX` and rebuilding. Memory map:
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| Start | End | Usage |
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| ------ | ------ | ----- |
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| 0x0000 | 0x3fff | 16KB internal RAM |
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| 0x4000 | 0x9fff | (unused) |
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| 0xa000 | 0xbfff | 6850 ACIA serial comm interface, emulated connecting to USB CDC-ACM virtual serial port |
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| 0xc000 | 0xffff | 16KB internal ROM |
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Thanks to Mike Chambers for the [fake6502](http://rubbermallet.org/fake6502.c) processor emulation core.
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For implementation notes see blog post *[pill_6502: 8-bit 6502 CPU and 6850 ACIA emulation on the STM32 blue pill to run Microsoft BASIC from 1977](https://satoshinm.github.io/blog/180113_stm32_6502_pill_6502_8_bit_6502_cpu_and_6850_acia_emulation_on_the_stm32_blue_pill_to_run_microsoft_basic_from_1977.html)*.
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