Device table added to IO Port 0xFF.

Programs/testPrograms/registryTest.asm

@@ -0,0 +1,50 @@
+; Asks the bus registry what this machine is made of.
+;
+; Writing a port number to the registry selects the port being asked about. Reading
+; gives that port's record a byte at a time: its device class, then its flags, then
+; zeroes once the record has run out. Nothing here touches the device being asked
+; about, which is the whole point: reading port 0x00 to find out what it is would take
+; a character off standard input and wait for one that never comes.
+;
+; Port 0x05 has nothing on it, and reads as class 0. That is the same answer a machine
+; with no registry at all would give, so software finds out whether it can enumerate by
+; enumerating.
+;
+; Correct output is:
+;   00 02 00      the console, class 2, no flags
+;   10 10 00      the test device, class 0x10, no flags
+;   FF 01 00      the registry itself, class 1, no flags
+;   05 00 00      nothing there
+
+#Include print.asm
+
+#Program
+
+start:
+  INIA 0x00
+  CALL reportPort
+  INIA 0x10
+  CALL reportPort
+  INIA 0xFF
+  CALL reportPort
+  INIA 0x05
+  CALL reportPort
+  HALT
+
+; Prints the port number, then the two bytes of its record. A is the port to ask about.
+reportPort:
+  PSHA
+  CALL printByteHex       ; The port we are asking about.
+  CALL blankSpace
+
+  POPA
+  OUTA 0xFF               ; Select it. This is the only write the registry accepts.
+
+  INA 0xFF                ; The device class.
+  CALL printByteHex
+  CALL blankSpace
+
+  INA 0xFF                ; The flags.
+  CALL printByteHex
+  CALL lineFeed
+  RET