zx128: further steps to working Microdrive read/write

This fixes the motor select logic. We can now have multiple devices loaded
without getting in a nasty mess. Still a write corruption problem to be tracked
down and writes to mdv3 (swap) bomb for reasons not yet understood

diff --git a/Kernel/platform-zx128/devmdv.c b/Kernel/platform-zx128/devmdv.c
index 8785a88..ceeface 100644 (file)
--- a/Kernel/platform-zx128/devmdv.c
+++ b/Kernel/platform-zx128/devmdv.c
@@ -90,7 +90,7 @@ static int mdv_transfer(uint8_t minor, bool is_read, uint8_t rawflag)
 
        while(nblock--) {
                mdv_sector = mdvmap[minor][block++];
-//             kprintf("Load sector %d to %d:%x\n", mdv_sector, mdv_page, mdv_buf);
+               kprintf("Load sector %d to %d:%x\n", mdv_sector, mdv_page, mdv_buf);
                irq = di();
                if (is_read)
                        err = mdv_bread();

diff --git a/Kernel/platform-zx128/microdrive.s b/Kernel/platform-zx128/microdrive.s
index 3e89b85..bc257ba 100644 (file)
--- a/Kernel/platform-zx128/microdrive.s
+++ b/Kernel/platform-zx128/microdrive.s
@@ -373,38 +373,41 @@ mdv_motor_a:
 ;
 ;      Now we will do 8 cycles of bit banging clock and data
 ;
-mdv_motor_lp:  ld a, #0xEF                     ; clock it
-               out (0xef), a                   ; select the microdrive sel
-                                               ; line
-               dec e                           ; are we there yet
+mdv_motor_lp:
+               dec e                           ; are we there yet ?
                jr nz, mdv_motor_0              ; send zero
 ;
 ;      Clock out an "on" bit
 ;
                ld a,#1
-               out (0xF7), a
+               out (0xF7), a                   ; data high
                ld a, #0xee
-               out (c), a                      
-               call nap_1ms
-               ld a, #0xec
-               jr mdv_motor_1
+               out (c), a                      ; clock, !data
+               call nap_1ms                    ; wait 1mS
+               ld a, #0xec                     ; !clock !data
+               jr mdv_motor_1                  ; into common path
 ;
 ;      Clock out an "off" bit
 ;
 mdv_motor_0:
-               xor a
-               out (0xEF), a
+               ld a, c                         ; 0xEF
+               out (0xEF), a                   ; clock 1
+               xor a                           ; 0 to data
+               out (0xF7), a
                call nap_1ms                    ; 1ms pulse 0
-               ld a, #0xED
+               ld a, #0xED                     ; clock 0
 
 mdv_motor_1:   out (c), a
-               call nap_1ms
-               djnz mdv_motor_lp
+               call nap_1ms                    ; 1ms wait
+               djnz mdv_motor_lp               ; round we go
+               ld a, #0x01
+               out (0xF7), a                   ; 1 to data
+               ld a, #0xEE                     ; clock high, !data
+               out (0xEF), a                   ; done
 
 ;
 ;      "Spin" up the drive - in our case get the tape to drive speed
 ;
-mdv_spin_up:
                ld bc, #13000
                jp nap
 
@@ -426,10 +429,11 @@ ret0:
 ;
 _mdv_motor_on: pop de
                pop hl
-               pop af
-               push af
+               pop bc
+               push bc
                push hl
                push de
+               ld a, c
                call mdv_motor
                jr ret0
 ;
@@ -463,6 +467,7 @@ _mdv_bwrite:
                ld a, (_mdv_page)
                or a
                ld a, e
+               push af
                call nz, switch_bank
                call mdv_store
                jr mdv_bout