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author | 2019-06-19 16:55:46 -0700 | |
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committer | 2019-06-19 19:55:46 -0400 | |
commit | 2e0f4af6ee693fb6f40183bc60ef16db826c8780 (patch) | |
tree | 2f3a9fd60d4bc5706f68e0a4cddb62dad65df65d /src/devices/bus/ss50 | |
parent | 492a9e1b48c47e8c1299fedf2efd5612b580f5d2 (diff) |
Pia6821 improvements (#5254)
* 6821pia: fix method names in comments
* zwackery: Remove PIA port A z_mask setting.
This would only be relevant if the PIA was read while in output mode.
These are inputs, and only read in input mode, so z_mask is not relevant.
* thomson: move pia pullup resistors from z_mask to read handler.
* 6821pia: remove unused set_port_a_z_mask calls.
* dgn_beta: move pia pullup resistors from z_mask to read handler.
* mpu3: Don't invert the VFD power on reset line.
It doesn't go through an inverter. I believe this was done to work
around a bug in the PIA port A implementation.
* pia6821: remove m_port_a_z_mask variable.
* 6821pia: For port A reads, only use the DDR for reading pins unless.
Provide an override option when a device depends on slightly undefined
behavior of an external device driving the pins and changing the value
read.
One board seems to need this (coinmstr). I don't have the schematics,
but it seems it uses this to check its meter operation.
Diffstat (limited to 'src/devices/bus/ss50')
-rw-r--r-- | src/devices/bus/ss50/mpc.cpp | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/devices/bus/ss50/mpc.cpp b/src/devices/bus/ss50/mpc.cpp index ba05d80e8e3..8563a289202 100644 --- a/src/devices/bus/ss50/mpc.cpp +++ b/src/devices/bus/ss50/mpc.cpp @@ -136,7 +136,7 @@ void ss50_mpc_device::device_start() WRITE_LINE_MEMBER(ss50_mpc_device::serial_input_w) { - m_pia->set_a_input(state << 7, 0x7f); + m_pia->set_a_input(state << 7); m_loopback->in_w<0>(state); } |