-homebrew/linux4004.cpp: Emulated Linux/4004 board.

* VFD is not emulated, but all other features are present.

-machine/sc16is741.cpp: Emulated basic SC16IS741A UART functionality in
 SPI interface mode.

-macine/spi_sdcard.cpp: Improved interface logic:
* Start in unprotected mode as specified by the standard.
* Ignore stop bits in unprotected mode - apparenty real cards do this.
* Set protected or unprotected mode in response to CMD59.
* Reset SPI logic when initially selected.

-machine/spi_psram.cpp: Started adding PSRAM QPI functionality.

-emu/diserial.cpp: Got rid of the per-instance parity lookup table.

New working systems
-------------------
Dmitry Grinberg Linux/4004

New working software list items (lnux4004.xml)
----------------------------------------------
uMIPS Linux 4.4.292+

Author: cuavas

hash/lnux4004.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0"?>
+<!DOCTYPE softwarelist SYSTEM "softwarelist.dtd">
+<!--
+license:CC0-1.0
+-->
+
+<softwarelist name="lnux4004" description="Linux/4004 SD Card images">
+
+	<software name="linux">
+		<description>uMIPS Linux 4.4.292+</description>
+		<year>2024</year>
+		<publisher>Dmitry Grinberg</publisher>
+		<part name="linux4004" interface="sdcard">
+			<diskarea name="harddriv">
+				<disk name="linux4004" sha1="6458018636d21845c95e1076b81c615e16a97975" writeable="yes" />
+			</diskarea>
+		</part>
+	</software>
+
+</softwarelist>

scripts/src/machine.lua

@@ -3320,6 +3320,17 @@ if (MACHINES["SAA5070"]~=null) then
 	}
 end
 
+---------------------------------------------------
+--
+--@src/devices/machine/sc16is741.h,MACHINES["SC16IS741"] = true
+---------------------------------------------------
+if (MACHINES["SC16IS741"]~=null) then
+	files {
+		MAME_DIR .. "src/devices/machine/sc16is741.cpp",
+		MAME_DIR .. "src/devices/machine/sc16is741.h",
+	}
+end
+
 ---------------------------------------------------
 --
 --@src/devices/machine/scc66470.h,MACHINES["SCC66470"] = true