zx+3: more FDC work - not quite there yet but close

diff --git a/Kernel/platform-zx+3/README b/Kernel/platform-zx+3/README
index 58f4e20..308d98d 100644 (file)
--- a/Kernel/platform-zx+3/README
+++ b/Kernel/platform-zx+3/README
@@ -56,8 +56,12 @@ load an app from 5D00-wherever. Still ugly.
 
 TODO
 
-Write boot block loader and load image (packed) from FDC
-Write FDC drivers
+Floppy drive B - set drive info and propogate it
+
+Floppy drive B - set parameters at init time
+
+Petty coloured stripes when reading/writing floppy
+
 Move buffers into upper part of bank 7 to see if can get kernel below
 C000 + E000 upwards to get bigger user image ?
 
@@ -75,22 +79,3 @@ user but screen mapped and buffers in rest of 7 ?
 in bottom of that chunk.
 
 Would give direct mapped video
-
-
-FDC
-
-Reuse amstradnc code
-
-How to twiddle tc ?? - do we in fact even have that ability ? looks like
-we instead have to discard or stuff bytes if sector size mismatched
-
-add delays 
-
-Use the jp p and other tricks to make timing on the spectrum
-for r/w loops
-
-Ensure we have the correct head settle on a seek
-
-motor on needs  big delay loop but can be done without di on (yay!)
-
-motor off is software

diff --git a/Kernel/platform-zx+3/fdc765.s b/Kernel/platform-zx+3/fdc765.s
index e6e46fc..5c28995 100644 (file)
--- a/Kernel/platform-zx+3/fdc765.s
+++ b/Kernel/platform-zx+3/fdc765.s
@@ -54,6 +54,7 @@
        .globl _fd765_sectors
        .globl _fd765_disc
 
+       .globl _vborder
 
        .globl diskmotor
 
@@ -154,6 +155,9 @@ _fd765_disc:
 
 ; Waits for a SEEK or RECALIBRATE command to finish by polling SENSE INTERRUPT STATUS.
 wait_for_seek_ending:
+       ld a,#0x05
+       out (0xFE),a
+
        ld a, #0x08                             ; SENSE INTERRUPT STATUS
        call fd765_tx
        call fd765_read_status
@@ -162,6 +166,9 @@ wait_for_seek_ending:
        bit 5, a                                ; SE, seek end
        jr z, wait_for_seek_ending
 
+       ld a, #0x02
+       out (0xFE),a
+
        ; Now settle the head (FIXME: what is the right value ?)
        ld a, #30               ; 30ms
 ;
@@ -177,6 +184,8 @@ wait_ms_loop2:
        dec a
        jr nz, wait_ms_loop
        pop bc
+       ld a,(_vborder)
+       out (0xFE),a
        ret
 
 _fd765_motor_off:
@@ -227,11 +236,14 @@ _fd765_do_read:
        push af
        call nz, map_process_always
 
+       ld a,#0x05
+       out (0xFE),a
+
        di                              ; performance critical,
                                        ; run with interrupts off
 
        xor a
-       call fd765_tx                   ; send the final unused 0 byte
+       call fd765_tx                   ; send the final unused byte
                                        ; to fire off the command       
        ld hl, (_fd765_buffer)
        ld bc, #0x2ffd
@@ -288,16 +300,38 @@ read_finished:
        ei
 
        call fd765_read_status
+       call tc_fix
+
+       ld a,(_vborder)
+       out (0xFE),a
 
        pop af
        ret z
        jp map_kernel
 
+;
+;      We will get an error reported that the command did not complete
+;      because the tc bit is not controllable. Spot that specific error
+;      and ignore it.
+;
+tc_fix:
+       ld hl,#_fd765_status
+       ld a,(hl)
+       and #0xC0
+       cp #0x40
+       ret nz
+       inc hl
+       bit 7,(hl)
+       ret z
+       res 7,(hl)
+       dec hl
+       res 6,(hl)
+       ret
+
 ;
 ;      Write is much like read just the other direction
 ;
 _fd765_do_write:
-       di                              ; performance critical, run with 
                                        ; interrupts off
        ld a, #0x45                     ; WRITE SECTOR MFM
        call setup_read_or_write
@@ -307,6 +341,11 @@ _fd765_do_write:
        push af
        call nz, map_process_always
 
+       ld a,#0x05
+       out (0xFE),a
+
+       di
+
        xor a
        call fd765_tx                   ; send the final unused 0 byte
                                        ; to fire off the command       
@@ -353,6 +392,10 @@ write_finished:
        call _fd765_do_nudge_tc         ; Tell FDC we've finished
        ei
        call fd765_read_status
+       call tc_fix
+
+       ld a,(_vborder)
+       out (0xFE),a
 
        pop af
        ret z
@@ -376,7 +419,7 @@ setup_read_or_write:
        add b                           ; add first sector
        dec a                           ; 6: last sector (*inclusive*)
        call fd765_tx
-       ld a, #27                       ; 7: Gap 3 length (27 is standard for 3.5" drives)
+       ld a, #0x2A                     ; 7: Gap 3 length (2A is standard for 3" drives)
        call fd765_tx
        ; We return with the final unused 0 value not written. We need all
        ; the other stuff lined up before we write this.