SPLIT-i のディスクの中身を眺めたい

import os

OUT_DIR = 'Alpha'
D88_HEADER = 0x2B0
SECTOR_INFO = 0x10
SECTOR_BODY = 0x100
SECTOR = SECTOR_INFO + SECTOR_BODY
ALPHA_DOS_INFO = 0x25000
ALPHA_DOS_SYSTEM = 0x3000
ENCODING = 'shift_jis'

with open('SPLIT-i 2014.d88', 'rb') as f:
    d88 = f.read(-1)
d88 = d88[D88_HEADER:]

raw = bytes()
for i in range(0, len(d88), SECTOR):
    raw += d88[i + SECTOR_INFO:i + SECTOR]

offset = ALPHA_DOS_INFO
os.makedirs(OUT_DIR, exist_ok=True)

with open(os.path.join(OUT_DIR, 'ALPHA_DOS.BIN'), 'wb') as f:
    f.write(raw[:ALPHA_DOS_SYSTEM])
current_address = ALPHA_DOS_SYSTEM

while True:
    if len(raw) < offset + 0x10 or raw[offset] == 0xFF:
        break
    base = raw[offset:offset + 6].rstrip().decode(encoding=ENCODING)
    suf = raw[offset + 6:offset + 9].rstrip().decode(encoding=ENCODING)
    name = base + '.' + suf if suf != '' else base
    typ = raw[offset + 9]
    if typ == 0xFF:
        break
    block = raw[offset + 10]
    address = block * 0x800
    if address < current_address:
        print(f'! Overrun detected ({address:X} < {current_address:X})')
    current_address = address
    tmp = raw[address:]
    if typ == 0x01:
        start = int.from_bytes(bytes=tmp[0:2], byteorder='little')
        end = int.from_bytes(bytes=tmp[2:4], byteorder='little')
        size = end - start
        tmp = tmp[4:4 + size]
        print(f'{name}: Binary 0x{start:04X}-0x{end:04X} (size 0x{size:04X})')
        with open(os.path.join(OUT_DIR, name), 'wb') as f:
            f.write(tmp)
        current_address += 4 + size
    elif typ == 0x80:
        print(f'{name}: Basic Text')
        with open(os.path.join(OUT_DIR, name), 'w') as f:
            p = 0
            while True:
                eol = int.from_bytes(bytes=tmp[p:p + 2], byteorder='little')
                p += 2
                if eol == 0:
                    break
                eol -= 2
                if tmp[eol] != 0:
                    print(f'! {name}: Unexpected EOL 0x{tmp[eol]:02X} at {address + eol:X}.')
                    break
                number = int.from_bytes(bytes=tmp[p:p + 2], byteorder='little')
                print(f'{number} ', end='', file=f)
                p += 2
                line = tmp[p:eol]
                if line[:3] == b'\x3A\x8F\xE9':
                    print(f"'{line[3:].decode(encoding=ENCODING)}", file=f)
                else:
                    print('(SOME BASIC STATEMENT)', file=f)  # NOT SUPPORTED
                p = eol + 1
        current_address += p
    else:
        print(f'! {name}: Unknown type 0x{typ:02X}.')
    offset += 0x10