v8080: first cut at a boot block

diff --git a/Kernel/platform-v8080/bootblock.s b/Kernel/platform-v8080/bootblock.s
new file mode 100644 (file)
index 0000000..a8ecd0b
--- /dev/null
+++ b/Kernel/platform-v8080/bootblock.s
@@ -0,0 +1,70 @@
+!
+!      8080 cpmsim loads the first (128 byte) sector from the disk into memory
+!      at 0 then executes it.  We are a bit tight on space here especially
+!      in 8080
+!
+!      Floppy loader: 
+!      Our boot disc is 77 tracks of 26 x 128 byte sectors, and we put
+!      the OS on tracks 58+, which means we can put a file system in the
+!      usual place providing its a bit smaller than a whole disc.
+!
+!
+!      assemble with ack 8080
+!
+
+!      Keep aslod happy
+
+               .sect .text
+               .sect .data
+               .sect .bss
+               .sect .rom
+               .sect .text
+
+
+console = 1
+drive = 10
+track = 11
+sector = 12
+command = 13
+status = 14
+dmal = 15
+dmah = 16
+sectorh = 17
+
+diskload:      di
+               xra a
+               out sectorh             ! sector high always 0
+               out drive               ! drive always 0
+               mvi a,57                ! start on track 58
+               out track
+               mvi c,19                ! number of tracks to load (56Kish)
+
+               lxi d,128
+
+load_tracks:   in track
+               inr a                   ! next track
+               out track
+               xra a                   ! sector 0 (first will be 1)
+               out sector
+               mvi b,26                ! sectors per track
+load_sectors:  
+               in sector
+               inr a
+               out sector              ! next sector
+               mov a, l
+               out dmal                ! dma low
+               mov a, h
+               out dmah                ! dma high
+               xra a                   ! read
+               out command             ! go
+               in status               ! status
+               dad d
+               dcr b
+               jnz load_sectors        ! 26 sectors = 3328 bytes
+               dcr c
+               jnz load_tracks
+               mvi a, 13
+               out 1
+               mvi a,10
+               out 1
+               jmp 0x88