F9E1h (or F9E3h) Schneiderware V/24 8251 USART chip Control
Clock source comes from a [[8253 chip]].
Clock input to that chip is jumper-selectable: 2MHz (default), or 1MHz. Caution: The RTS/CTS and DSR/DTR handshaking signals are disabled by default (via jumpers) (and, in worst case, also by additional inaccesible hardwired connections, hidden underneath of the jumpers)
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