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Neon816: README update
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# Neon816
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This is a port to Lenore Byron's [Neon816](https://hackaday.io/project/164325-neon816) system. The Neon816 Developer Edition ships with a small 16-bit Forth.
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This is a port to Lenore Byron's [Neon816](https://hackaday.io/project/164325-neon816) system. The Neon816 Developer
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Edition ships with a small 16-bit Forth.
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OF816 for the Neon816 is configured to run as an alternative firmware out of bank $20. With a little ajustment, it could be configured to run out of bank $21 (but starting it is an excercise for the reader).
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OF816 for the Neon816 is configured to run as an alternative firmware out of bank $20. With a little ajustment, it
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could be configured to run out of bank $21 (but starting it is an excercise for the reader).
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It configures the MMU and serial port like NeonFORTH does. The direct page, stack, and return stack occupy the first $400 bytes of RAM.
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It configures the MMU and serial port like NeonFORTH does. The direct page, stack, and return stack occupy the first
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$400 bytes of RAM.
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To build OF816 for the Neon816, change to the platform directory and run
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``build.sh``. It will output a 64K binary named ``of816-neon.bin`` that can be flashed into the Neon's firmware. See below for installation instructions.
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``build.sh``. It will output a 64K binary named ``of816-neon.bin`` that can be flashed into the Neon's firmware.
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See below for installation instructions.
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## Port Features
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Hopefully this section will be filled up with stuff that works like Lenore's
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Forth. See the [Neon816 Manual](https://cdn.hackaday.io/files/1643257030480800/sysmanual.pdf). But right now, it's just a bare port with no system-specific extensions.
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Hardware access words with the same semantics as NeonFORTH are found in the NEON816 dictionary.
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## Installation
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The hardware access dictionary is currently not complete but has the words for accessing the PS/2 ports, I2C2,
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and VDC.
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Execute ``also neon816`` to gain access to the words.
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See the [Neon816 Manual](https://cdn.hackaday.io/files/1643257030480800/sysmanual.pdf) for descriptions of the
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specific words.
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## Installation / Removal
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The instructions assume you are running Linux. The Neon firmware loader is supported under Linux only.
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### Installing OF816
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**THIS WILL OVERWRITE THE NEON'S ORIGINAL FIRMWARE!**
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@ -23,11 +38,15 @@ Forth. See the [Neon816 Manual](https://cdn.hackaday.io/files/1643257030480800/
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**READ _ALL_ OF THE FOLLOWING BEFORE PROCEEDING AND DO NOT PROCEED IF ANY OF THIS MAKES YOU UNCOMFORTABLE!**
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After building the firmware image, the image must be converted to Intel Hex format. I like the bin2hex tool found [here](https://grumpf.hope-2000.org) (page is in German). Build the ``bin2hex`` binary and execute: ``bin2hex of816-neon.bin > of816-neon.hex``
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After building the firmware image, the image must be converted to Intel Hex format. I like the bin2hex tool originally
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found [here](https://grumpf.hope-2000.org) (page is in German), also in my [Github repo](https://github.com/mgcaret/bin2hex).
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Build the ``bin2hex`` binary and execute: ``bin2hex of816-neon.bin > of816-neon.hex``
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Once you have the .hex file, you will need to use the [Neon firmware loader](https://hackaday.io/project/164325-neon816) to install the image. This requires an FTDI cable connected to the 3.3V UART header on the Neon816 system board.
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Once you have the .hex file, you will need to use the [Neon firmware loader](https://hackaday.io/project/164325-neon816)
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to install the image. This requires an FTDI cable connected to the 3.3V UART header on the Neon816 system board.
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To back up the original firmware, you will need to add an additional command routine to neonprog.cpp (add it after the write command):
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To back up the original firmware, you will need to add an additional command routine to neonprog.cpp (add it after the
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write command):
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```
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else if(!strcmp(cmd,"dumprom")) {
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@ -59,8 +78,40 @@ build neonprog then start it with ``neonprog /dev/ttyUSBx`` (replace device with
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From within neonprog, execute ``dumprom backup.bin`` to save an image of both ROM banks to ``backup.bin``.
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Once the backup has finished (it will take a while), you can proceed to the installation of OF816 with ``flash of816-neon.hex``. This will also take a while. When it is done, reset your Neon and OF816 should start.
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Once the backup has finished (it will take a while), you can proceed to the installation of OF816 with
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``flash of816-neon.hex``. This will also take a while. When it is done, reset your Neon and OF816 should start.
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## Restoring the Original NeonFORTH Firmware
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Since the Neon (at the time of this writing) only ships with the first bank of flash occupied, first, split your backup with ``split -b 65536 backup.bin``. This will output two files, ``xaa`` and ``xab`` that are bank $20 and bank $21, respectively. Then run ``bin2hex xaa > neonforth.hex``. You can then flash this with neonprog using ``flash neonforth.hex``. Once it's done, reset your Neon and you should see the original firmware running.
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Since the Neon (at the time of this writing) only ships with the first bank of flash occupied, first, split your backup
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with ``split -b 65536 backup.bin``. This will output two files, ``xaa`` and ``xab`` that are bank $20 and bank $21,
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respectively. Then run ``bin2hex xaa > neonforth.hex``. You can then flash this with neonprog using
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``flash neonforth.hex``. Once it's done, reset your Neon and you should see the original firmware running.
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## A Comparison of OF816 and NeonFORTH
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NeonFORTH, which comes with the Neon816, is a compact 16-bit Forth specifically designed for the system by its creator.
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OF816 is a portable 32-bit Forth that is designed to run on many 65816 systems. As a result of its 32-bit cells, it has
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a flat view of the 65816 address space. A negative consequence is that it is slower and uses more memory than a system
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like NeonFORTH.
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A general comparison:
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| OF816 | NeonFORTH |
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|------------------------------------------|----------------------------------------------|
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| 32-bit cells | 16-bit cells |
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| First-class access to '816 address space | Special words to access memory beyond bank 0 |
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| Slower | Faster |
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| More RAM/ROM use | Less RAM/ROM use |
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| ANSI standard Forth | Not ANSI standard |
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| FCode support | No FCode support |
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| Larger dictionary | Smaller dictionary |
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Additionally, as NeonFORTH is maintained by the creator of the Neon816, it is going to have features specific to the
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Neon816 sooner than OF816 will have them.
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Overall, NeonFORTH is small, and well suited to basic experiments with the Neon816's hardware. OF816 is more powerful
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in the large built-in dictionary, and in the way it handles numbers, address space, exceptions, and stack over/
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underflow. However, this makes it slower and use more memory.
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