initial support for internal MEGA65 DOS

src/dos_m65/dos_vectable.s

@@ -0,0 +1,40 @@
+
+// A vector table to integrate DOS with the MEGA65 Kernal
+
+.word dos_INIT
+.word dos_HASUNIT
+.word dos_ACPTR
+.word dos_CIOUT
+.word dos_LISTEN
+.word dos_SECOND
+.word dos_TALK
+.word dos_TKSA
+.word dos_UNTLK
+.word dos_UNLSN
+
+
+// Dummy implementations - XXX to be replaced with real ones
+
+dos_INIT:
+	nop
+dos_HASUNIT:
+	nop
+dos_ACPTR:
+	nop
+dos_CIOUT:
+	nop
+dos_LISTEN:
+	nop
+dos_SECOND:
+	nop
+dos_TALK:
+	nop
+dos_TKSA:
+	nop
+dos_UNTLK:
+	nop
+dos_UNLSN:
+	nop
+
+	sec
+	rts

src/kernal/iec_fast/dos_m65.s

@@ -0,0 +1,19 @@
+// #LAYOUT# M65 KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+//
+// MEGA65 pseudo-IEC internal DOS support
+//
+
+.label VDOS_INIT    = $4000
+.label VDOS_HASUNIT = $4002
+.label VDOS_ACPTR   = $4004
+.label VDOS_CIOUT   = $4006
+.label VDOS_LISTEN  = $4008
+.label VDOS_SECOND  = $400A
+.label VDOS_TALK    = $400C
+.label VDOS_TKSA    = $400E
+.label VDOS_UNTLK   = $4010
+.label VDOS_UNLSN   = $4012
+
+// XXX implement support