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(nw) i8251 : added notes

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Robbbert 2019-09-11 14:53:01 +10:00
parent 20b1e7fce1
commit 4279146dff
1 changed files with 8 additions and 4 deletions
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12
src/devices/machine/i8251.cpp
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@ -1,8 +1,8 @@
// license:BSD-3-Clause // license:BSD-3-Clause
// copyright-holders:smf // copyright-holders:smf, Robbbert
/********************************************************************* /*********************************************************************
i8251.c i8251.cpp
Intel 8251 Universal Synchronous/Asynchronous Receiver Transmitter code Intel 8251 Universal Synchronous/Asynchronous Receiver Transmitter code
NEC uPD71051 is a clone NEC uPD71051 is a clone
@ -10,6 +10,12 @@
The V53/V53A use a customized version with only the Asynchronous mode The V53/V53A use a customized version with only the Asynchronous mode
and a split command / mode register and a split command / mode register
To Do:
- BRKDET: if, in Async mode, 16 low RxD bits in succession are clocked in,
the SYNDET pin & status must go high. It will go low upon a
status read, same as what happens with sync.
- SYNC/BISYNC with PARITY is not tested, and therefore possibly buggy.
*********************************************************************/ *********************************************************************/
@ -684,8 +690,6 @@ void i8251_device::mode_w(uint8_t data)
receive_register_reset(); receive_register_reset();
m_txc_count = 0; m_txc_count = 0;
// m_status = I8251_STATUS_TX_EMPTY | I8251_STATUS_TX_READY;
} }
void i8251_device::sync1_w(uint8_t data) void i8251_device::sync1_w(uint8_t data)