bank94: fix some obvious bugs before we try it

diff --git a/Kernel/platform-trs80/trs80-bank94.s b/Kernel/platform-trs80/trs80-bank94.s
index ca19e24..29f93e8 100644 (file)
--- a/Kernel/platform-trs80/trs80-bank94.s
+++ b/Kernel/platform-trs80/trs80-bank94.s
@@ -35,11 +35,6 @@
 
 init_hardware:
            call detect94
-           or a
-           jr z, extended_system
-            ; set system RAM size
-            ld hl, #128
-extended_system:
             ld (_ramsize), hl
            ld de, #64          ; for kernel
            or a
@@ -72,34 +67,11 @@ save94:         .db 0x01
 _opreg:            .db 0x06    ; kernel map, 80 columns
 _modout:    .db 0x50   ; 80 column, sound enabled, altchars off,
                        ; external I/O enabled, 4MHz
-_mirror94:  .db 0x01   ; mirror of 0x94 port
 
 detect94:
-;
-;      This will spot 0x94 bank switches eventually. For now report none
-;
-           ld a, (_opreg)
-           and #0x8C
-           or #0x73
-           out (_opreg), a
-           xor a
-           out (0x94), a
-;
-;      If we have 0x94 banking then the the low 32K is a mirror of the high
-;      32K
-;
-           ld hl, #0x800
-           ld a, (0x8800)
-           cp (hl)
-           jr nz, nobank94
-;
-;      Could be the same could be luck.
-;
-           inc (hl)
-           ld a, (0x8800)
-           cp (hl)
-           jr nz, nobank64_f1
-           dec (hl)
+            in a,(0x94)
+            cp #0xFF
+             jr z, nobank94
 ;
 ;      Seems we have banking extensions present
 ;
@@ -109,14 +81,15 @@ detect94:
 ;      it. When we see a bank not reporting A5 we have found the wrap.
 ;
            ld a, #0xA5
-           ld bc, #0x3f94
+           ld bc, #0x1f94
+           ld hl, #0x80        ; pick somewhere which won't hit us!
 markall:
            out (c), b
            ld (hl), a
            djnz markall
 
 scanall:    inc b
-           bit 6, a
+           bit 5, b
            jr nz, scandone
            out (c), b
            cp (hl)             ; Still A5 ?
@@ -136,11 +109,7 @@ scandone:
            ld l, a     ; Report size in HL
            ld h, b
            ret
-           
-           
-nobank64_f1
-           dec (hl)
-nobank64:
+nobank94:
            xor a
            ld h, a
            ld l, #128          ; We ought to check/abort on a 64K box ?
@@ -181,9 +150,8 @@ maplo:
            ld (_opreg), a
            out (0x84), a
            ld a, (hl)
-           and #0x3F
+           and #0x1F
            ret z               ; not using bank94
-           ld (_mirror94), a
            out (0x94), a
            ret
 
@@ -201,9 +169,8 @@ maplo2:
            ld (_opreg), a
            out (0x84), a
            ld a, b
-           and #0x3f
+           and #0x1f
            jr z, nobank94      ; zero means no bank94 hw present
-           ld (_mirror94), a
            out (0x94), a
 nobank94:
            pop bc
@@ -223,7 +190,7 @@ map_save:   push af
            ld a, (_opreg)
            and #0x73
            ld (opsave), a
-           ld a, (_mirror94)
+           in a,(0x94)
            ld (save94), a
            pop af
            ret
@@ -238,7 +205,7 @@ map_restore:
            ld (_opreg), a
            out (0x84), a
            ld a, b
-           and #0x3f
+           and #0x1f
            jr z, norestore94
            out (0x94), a
 norestore94: