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USER_MANUAL.md

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UNICODE UTF-8 STANDARD INPUT TERMINAL

This user manual describes operation of your new, state of the art, UTF-8 binary input terminal. While this is a relatively simple data entry device, several functions are not necessarily obvious, so all users are encouraged to read this short manual.

Power-up

When the device is turned on, it scans all fonts installed in the fonts/ directory on the SD card for fast access later. The Unicode logo is displayed on screen while this scan is in progress, which takes around 30 seconds with the standard font package. The colouring of the logo represents the progress of this scan. When the logo is fully coloured, all fonts have been processed and the device is ready to use.

The USB interface of the device will not activate until after this initial loading is complete.

Data Entry

In all modes:

  • The most significant byte is selected first, then right-shifted by briefly engaging the SHIFT switch. For example, to make the value 0x1234 you first select 0x12 on the DATA INPUT switches, press the SHIFT switch momentarily, then select 0x34 on the DATA INPUT switches: your buffer now has the desired value and can be sent.

  • Pressing the SEND switch will output the current buffer to the host computer system. The buffer will be reset to the current DATA INPUT byte selection after sending unless shift-lock is engaged.

  • Holding SHIFT enables shift-lock. Shift-lock retains the most significant bytes of the buffer across SEND operations, allowing multiple codepoints in the same range to be entered rapidly. For example with shift lock enabled, you can enter 0x1F40D, press send, then simply flip DATA INPUT bit 6 and press send again for 0x1F44D.

  • Pressing the MODE switch momentarily will cycle between the input and view modes described below. The buffer and shift-lock will be retained while switching modes.

  • Holding CLEAR resets the buffer to the current DATA INPUT selection and disables shift-lock. The selected mode remains active.

Modes

Codepoint Mode (HEX, DEC)

  • Entry of a codepoint value via DATA INPUT and SHIFT

  • Codepoint value is displayed in hexadecimal (HEX) or decimal (DEC), centred at the bottom of the screen.

  • The corresponding glyph is rendered if the codepoint is found in any of the available fonts.

  • Unicode block and codepoint names are displayed at the top of the screen when codepoint is valid.

UTF-8 Mode (UTF-8)

  • Entry of a 1-4 byte UTF-8 sequence via DATA INPUT and SHIFT

  • If an invalid encoding is entered, binary literals will be shown with problematic bits highlighted in red.

  • The SHIFT operation is automatically limited to the encoded sequence length.

  • A glyph will be rendered when a valid UTF-8 sequence is entered, if found in the available fonts.

  • Unicode block and codepoint names are displayed at the top of the screen when codepoint is valid.

Changing to this mode will show the UTF-8 encoding of the codepoint selected in the previous mode. The low byte may not match the DATA INPUT switches at this time. When the DATA INPUT changes, the low byte will be updated.

Numeric / Programmer Mode (LITERAL)

  • Always shows a large hexadecimal representation of the input buffer

  • Pressing SEND writes the literal hex value like "0xF1"

Notes

Glyph display

Glyphs are always drawn so their visible components are centred on screen, rather than using a fixed baseline. This means glyphs lose some positional information, which is not technically accurate, but provides consistent positioning for glyphs of all shapes and sizes, regardless of how their script handles baselines.