sam: update boot logic

Thanks to the various Sam folks who explained how BOOT works

diff --git a/Kernel/platform-sam/boot.s b/Kernel/platform-sam/boot.s
index ce28200..140b448 100644 (file)
--- a/Kernel/platform-sam/boot.s
+++ b/Kernel/platform-sam/boot.s
@@ -1,5 +1,5 @@
 ;
-;      Boot block, loaded at 0x4000
+;      Boot block, loaded at 0x4000 in the top bank that is free (varies)
 ;
 ;      Banks and SP we need to double check are ROM0/1/2/3 and valid
 ;
@@ -36,7 +36,7 @@ CMD_STEPIN .equ 0x58
        .db 0,0,0,0,0,0,0,0     ; need to work out what goes here
 boot:
        di
-       ld de,#2                ; track 0 sector 2 (we are sector 0)
+       ld de,#0x0401           ; track 4 sector 2 (we are sector 1)
        ld a,e                  ; Start in bank 2
        ld hl,#0x8000           ; Which we map high
        out (HIMEM),a
@@ -82,7 +82,7 @@ wait: in a,(STATUS)           ; Wait for DRQ
        ;       We read 14 tracks minus 1 sector which loads us
        ;
        ;
-       ld a,#14
+       ld a,#18
        cp d
        ; Jump to the start of the last bank loaded. This is actually
        ; packed up boot stuff and font. We loaded 5.5K here, of which 4K