ussr/bk.cpp: K1801VP1-014 keyboard controller and MS7008 keyboard #12027
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| m_write_virq(m_rxrdy); | ||
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| reset_key_state(); | ||
| start_processing(attotime::from_hz(2'400)); // FIXME real device does not use polling |
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How does it work if it doesn’t scanning a key matrix? Does it have a dedicated input line per key? Does it keep all rows driven until it detects a change on a column and then scan for the row that changed?
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I don't quite understand it but it looks like option 3 with extra steps (https://github.com/1801BM1/k1801/blob/master/014/ describes the process)
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Oh, interesting. When it detects the key switch connecting the row pull-up resistor to the column line, then it actively drives the column low and senses which row line gets pulled down. It then holds the state until the key is released.
It doesn’t need scanning logic at all, at the cost of not even attempting to deal with simultaneous key-presses besides the modifiers.
| // save state | ||
| save_item(NAME(m_key_code)); | ||
| save_item(NAME(m_kbd_state)); |
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Won’t you need to save m_key_irq_vector and m_rxrdy as well? They seem to be live state.
src/mame/ussr/1801vp014.h
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| devcb_write_line m_write_halt; | ||
| devcb_write8 m_write_data; | ||
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| line_state m_rxrdy; |
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line_state is really only for things that support the HOLD_LINE hack. It also isn’t explicitly sized and will cause an issue with save states. Just use a uint8_t or something.
src/mame/ussr/1801vp014.cpp
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| // LIVE DEVICE | ||
| //************************************************************************** | ||
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| INPUT_PORTS_START(ms7008) |
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It would be nice to have Russian key cap labels for the letter keys as well. Also, this should be static INPUT_PORTS_START(...).
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