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Recipes contain bits and pieces of hardware-related knowledge, but these bits feel sparse. I've been wanting to consolidate hardware- related documentation for a while, but always fell at odds with the recipes organisation. We don't have recipes anymore, just a /doc/hw section that contains hardware-related documentation which often translate to precise instructions to run Collapse OS on a specific machine. With this new organisation, I hope to end up with a better, more solid documentation.
146 lines
4.9 KiB
Plaintext
146 lines
4.9 KiB
Plaintext
# TI-84+
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The TI-84+ is a machine with many advantages, one being that
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it's very popular. It also has a lot of flash memory and RAM.
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Its builtin keyboard and screen, however, are hard to use,
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especially the screen. With a tiny font, the best we can get is
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a 24x10 console.
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There is, however, a built-in USB controller that might prove
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very handy.
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I haven't opened one up yet, but apparently, they have limited
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scavenging value because its z80 CPU is packaged in a
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TI-specific chip. Due to its sturdy design, and its ample RAM
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and flash, we could imagine it becoming a valuable piece of
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equipment if found intact.
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The best pre-collapse ressource about it is WikiTI[1].
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As it is now, with its tiny screen and cumbersome keyboard,
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Collapse OS is not really usable on the TI-84+. One could
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imagine a scenario where one has a terminal and uses the TI-84+
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through the link for its large amount of flash and RAM. But
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using it standalone? Nah, not even post-collapse.
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Therefore, this recipe is more of a "look, I run!" demo.
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# Gathering parts
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* A TI-84+
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* A USB cable
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* tilp[2]
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* mktiupgrade[3]
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# Build the ROM
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Running "make" in /arc/z80/ti84 will result in "os.rom" being
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created.
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# Emulate
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Collapse OS has a builtin TI-84+ emulator using XCB for display
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in emul/hw/ti. You can invoke it with "make emul".
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You will start with a blank screen, it's normal, you haven't
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pressed the "ON" key yet. This key is mapped to tilde (~) in the
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emulator. Once you press it, the Collapse OS prompt will appear.
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See emul/hw/ti/README.md for details.
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# Upload to the calculator
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# Background notes
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Getting software to run on it is a bit tricky because it needs
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to be signed with TI-issued private keys. Those keys have long
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been found and are included in keys/. With the help of the
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mktiupgrade, an upgrade file can be prepared and then sent
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through the USB port with the help of tilp.
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That, however, requires a modern computing environment. As of
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now, there is no way of installing Collapse OS on a TI-8X+
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calculator from another Collapse OS system.
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Because it is not on the roadmap to implement complex
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cryptography in Collapse OS, the plan is to build a series of
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pre-signed bootloader images. The bootloader would then receive
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data through either the Link jack or the USB port and write that
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to flash (I haven't verified that yet, but I hope that data
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written to flash this way isn't verified cryptographically by
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the calculator).
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As modern computing fades away, those pre-signed binaries would
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become opaque, but at least, would allow bootstrapping from
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post-modern computers.
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# Instructions
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WARNING: the instructions below will wipe all the contents of
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your calculator, including TI-OS.
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To send your ROM to the calculator, you'll need two more tools:
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mktiupgrade and tilp.
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Once you have them, you need to place your calculator in
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"bootloader mode", that is, in a mode where it's ready to
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receive a new binary from its USB cable. To do that you need
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to:
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1. Shut down the calculator by removing one of the battery.
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2. Hold the DEL key
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3. But the battery back.
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4. A "Waiting... Please install operating system now" message\
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will appear.
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Once this is done, you can plug the USB cable in your computer
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and run "make send". This will create an "upgrade file" with
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mktiupgrade and then push that upgrade file with tilp. tilp will
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prompt you at some point. Press "1" to continue.
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When this is done, you can press the ON button to see Collapse
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OS' prompt!
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# Validation errors
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Sometimes, when uploading an upgrade file to your calculator,
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you'll get a validation error. You can always try again, but in
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my own experience, some specific binaries will simply always be
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refused by the calculator. Adding random "nop" or reordering
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lines (when it makes sense, of course) should fix the problem.
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I'm not sure whether it's a bug with the calculator or with
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mktiupgrade.
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# Usage
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The shell works like a normal BASIC shell, but with very tight
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screen space.
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When pressing a "normal" key, it spits the symbol associated to
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it depending on the current mode. In normal mode, it spits the
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digit/symbol. In Alpha mode, it spits the letter. In Alpha+2nd,
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it spits the uppercase letter.
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Special keys are Alpha and 2nd. Pressing them toggles the
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associated mode. Alpha and 2nd mode don't persist for more than
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one character. After the character is spit, mode reset to
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normal.
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Pressing 2nd then Alpha will toggle the A-Lock mode, which is a
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persistent mode. The A-Lock mode makes Alpha enabled all the
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time. While A-Lock mode is enabled, you have to enable Alpha to
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spit a digit/symbol.
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Simultaneous keypresses have undefined behavior. One of the keys
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will be registered as pressed. Mode key don't work by
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simultaneously pressing them with a "normal" key. The presses
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must be sequential.
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Keys that aren't a digit, a letter, a symbol that is part of
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7-bit ASCII or one of the two mode key have no effect.
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[1]: http://wikiti.brandonw.net/index.php
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[2]: http://lpg.ticalc.org/prj_tilp/
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[3]: https://github.com/KnightOS/mktiupgrade
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