msx2: switch to R800 cpu on boot if available

We want to boot fast on TurboR.

diff --git a/Kernel/platform-msx2/bootrom.s b/Kernel/platform-msx2/bootrom.s
index f171737..0a9a10c 100644 (file)
--- a/Kernel/platform-msx2/bootrom.s
+++ b/Kernel/platform-msx2/bootrom.s
@@ -23,6 +23,14 @@ bootstrap:
                di
                ld sp,#0xf340       ; temporary stack
 
+               ;
+               ; enable R800 CPU if available
+               ;
+               ld a,(BIOS_CHGCPU)
+               cp  #0xC3
+               ld  a,#0x81                 ; run only in rom mode, as we do not use BIOS better save 4 ram pages
+               call z,#BIOS_CHGCPU
+
                ; FIXME: init vdp using bios so that font is in place after vdpinit
                ld a,#0x50
                ld (0xf3ae),a

diff --git a/Kernel/platform-msx2/msx2.def b/Kernel/platform-msx2/msx2.def
index ae36d01..11f3089 100644 (file)
--- a/Kernel/platform-msx2/msx2.def
+++ b/Kernel/platform-msx2/msx2.def
@@ -40,4 +40,8 @@ BIOS_VDP_IOPORT                   .equ 0x0006
 OPENMSX_DEBUG1             .equ 0x2E
 OPENMSX_DEBUG2             .equ 0x2F
 
+;
+; TurboR CPU mode select
+;
+BIOS_CHGCPU                .equ 0x180