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;
; TAPE LOADER USING THE BIOS
;
TAPION = 0x00e1
TAPIN = 0x00e4
TAPIOF = 0x00e7
DISSCR = 0x0041
ENASCR = 0x0044
LDIRVM = 0x005c
CHGMOD = 0x005f
CHGCLR = 0x0062
FORCLR = 0xf3e9
BAKCLR = 0xf3ea
BDRCLR = 0xf3eb
CHPUT = 0x00a2
TOTEXT = 0x00d2
ENASLT = 0x0024
RSLREG = 0x0138
.area _CODE
di
; init the stack
ld sp, #0xf380
; sslot fix
ld a, (0xffff)
cpl
and #0xf0
ld c, a
rrca
rrca
rrca
rrca
or c
ld (0xffff),a
in a, (#0xa8)
; map RAM on 0x8000
and #0xcf
ld c, #16
ld hl, #0x8000
call select_ram
; map RAM on 0x4000
and #0xf3
ld c, #4
ld hl, #0x4000
call select_ram
ei
; now we have: ROM RAM RAM RAM
; set these to black
ld a, #1
ld (FORCLR), a
ld (BAKCLR), a
ld (BDRCLR), a
call CHGCLR
; load the loading screen
call load_custom_block
ld hl, (block_addr)
ld de, #0x4000
call ap_uncompress
call upload_screen
; load the code
call load_custom_block
ld hl, (block_addr)
ld de, #0x4000
call ap_uncompress
; cas main
jp 0x4010
upload_screen:
ld a, #2
call CHGMOD
call DISSCR
ld hl, #0x4000
ld de, #0
ld bc, #256 * 8
call LDIRVM
ld hl, #0x4000 + 256 * 8
ld de, #256 * 8
ld bc, #256 * 8
call LDIRVM
ld hl, #0x4000 + 256 * 8 * 2
ld de, #256 * 8 * 2
ld bc, #256 * 8
call LDIRVM
ld hl, #0x4000 + 256 * 8 * 3
ld de, #0x2000
ld bc, #256 * 8
call LDIRVM
ld hl, #0x4000 + 256 * 8 * 4
ld de, #0x2000 + 256 * 8
ld bc, #256 * 8
call LDIRVM
ld hl, #0x4000 + 256 * 8 * 5
ld de, #0x2000 + 256 * 8 * 2
ld bc, #256 * 8
call LDIRVM
jp ENASCR
load_custom_block:
call TAPION
jp c, tape_error
ld bc, #4
ld hl, #block_addr
call load_block
ld bc, (block_len)
ld hl, (block_addr)
call load_block
jp TAPIOF
load_block:
ld a, r
and #15
out (#0x99), a
ld a, #0x87
nop
nop
out (#0x99), a
push bc
push hl
call TAPIN
pop hl
pop bc
jr c, tape_error
ld (hl), a
inc hl
dec bc
ld a, b
or c
jr nz, load_block
ld a, #1
out (#0x99), a
ld a, #0x87
nop
nop
out (#0x99), a
ret
select_ram:
ld b, #4
select_ram_loop:
out (#0xa8), a
ld (hl), a
cp (hl)
ret z
add a, c
djnz select_ram_loop
memory_error:
ld hl, #mem_err_message
jp display_error
tape_error:
ld hl, #tape_err_message
display_error:
push hl
call TOTEXT
ld a, #1
ld (BAKCLR), a
ld (BDRCLR), a
ld a, #6
ld (FORCLR), a
call CHGCLR
pop hl
print_loop:
ld a, (hl)
or a
jr z, halt0
inc hl
call CHPUT
jr print_loop
halt0:
halt
jr halt0
tape_err_message:
.str "TAPE READ ERROR"
.db 0
mem_err_message:
.str "MEMORY INIT ERROR"
.db 0
.area _DATA
block_addr:
.dw 2
block_len:
.dw 2
|
