TAP files are used by emulators of ZX Spectrum computer (released in 1982 by Sinclair Research). TAP file stores blocks of data as if they are written to magnetic tape, which was used as primary media for ZX Spectrum. Contents of this file can be viewed as a very simple linear filesystem, storing named files with some basic metainformation prepended as a header.
This page hosts a formal specification of ZX Spectrum tape file using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
digraph {
rankdir=LR;
node [shape=plaintext];
subgraph cluster__zx_spectrum_tap {
label="ZxSpectrumTap";
graph[style=dotted];
zx_spectrum_tap__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="blocks_pos">0</TD><TD PORT="blocks_size">...</TD><TD>Block</TD><TD PORT="blocks_type">blocks</TD></TR>
<TR><TD COLSPAN="4" PORT="blocks__repeat">repeat to end of stream</TD></TR>
</TABLE>>];
subgraph cluster__block {
label="ZxSpectrumTap::Block";
graph[style=dotted];
block__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="len_block_pos">0</TD><TD PORT="len_block_size">2</TD><TD>u2le</TD><TD PORT="len_block_type">len_block</TD></TR>
<TR><TD PORT="flag_pos">2</TD><TD PORT="flag_size">1</TD><TD>u1→FlagEnum</TD><TD PORT="flag_type">flag</TD></TR>
<TR><TD PORT="header_pos">3</TD><TD PORT="header_size">...</TD><TD>Header</TD><TD PORT="header_type">header</TD></TR>
<TR><TD PORT="data_pos">...</TD><TD PORT="data_size">(header.len_data + 4)</TD><TD></TD><TD PORT="data_type">data</TD></TR>
<TR><TD PORT="headerless_data_pos">...</TD><TD PORT="headerless_data_size">(len_block - 1)</TD><TD></TD><TD PORT="headerless_data_type">headerless_data</TD></TR>
</TABLE>>];
}
subgraph cluster__program_params {
label="ZxSpectrumTap::ProgramParams";
graph[style=dotted];
program_params__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="autostart_line_pos">0</TD><TD PORT="autostart_line_size">2</TD><TD>u2le</TD><TD PORT="autostart_line_type">autostart_line</TD></TR>
<TR><TD PORT="len_program_pos">2</TD><TD PORT="len_program_size">2</TD><TD>u2le</TD><TD PORT="len_program_type">len_program</TD></TR>
</TABLE>>];
}
subgraph cluster__bytes_params {
label="ZxSpectrumTap::BytesParams";
graph[style=dotted];
bytes_params__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="start_address_pos">0</TD><TD PORT="start_address_size">2</TD><TD>u2le</TD><TD PORT="start_address_type">start_address</TD></TR>
<TR><TD PORT="reserved_pos">2</TD><TD PORT="reserved_size">2</TD><TD></TD><TD PORT="reserved_type">reserved</TD></TR>
</TABLE>>];
}
subgraph cluster__header {
label="ZxSpectrumTap::Header";
graph[style=dotted];
header__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="header_type_pos">0</TD><TD PORT="header_type_size">1</TD><TD>u1→HeaderTypeEnum</TD><TD PORT="header_type_type">header_type</TD></TR>
<TR><TD PORT="filename_pos">1</TD><TD PORT="filename_size">10</TD><TD></TD><TD PORT="filename_type">filename</TD></TR>
<TR><TD PORT="len_data_pos">11</TD><TD PORT="len_data_size">2</TD><TD>u2le</TD><TD PORT="len_data_type">len_data</TD></TR>
<TR><TD PORT="params_pos">13</TD><TD PORT="params_size">...</TD><TD>switch (header_type)</TD><TD PORT="params_type">params</TD></TR>
<TR><TD PORT="checksum_pos">...</TD><TD PORT="checksum_size">1</TD><TD>u1</TD><TD PORT="checksum_type">checksum</TD></TR>
</TABLE>>];
header__seq_params_switch [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#F0F2E4">case</TD><TD BGCOLOR="#F0F2E4">type</TD></TR>
<TR><TD>:header_type_enum_program</TD><TD PORT="case0">ProgramParams</TD></TR>
<TR><TD>:header_type_enum_num_array</TD><TD PORT="case1">ArrayParams</TD></TR>
<TR><TD>:header_type_enum_char_array</TD><TD PORT="case2">ArrayParams</TD></TR>
<TR><TD>:header_type_enum_bytes</TD><TD PORT="case3">BytesParams</TD></TR>
</TABLE>>];
}
subgraph cluster__array_params {
label="ZxSpectrumTap::ArrayParams";
graph[style=dotted];
array_params__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="reserved_pos">0</TD><TD PORT="reserved_size">1</TD><TD>u1</TD><TD PORT="reserved_type">reserved</TD></TR>
<TR><TD PORT="var_name_pos">1</TD><TD PORT="var_name_size">1</TD><TD>u1</TD><TD PORT="var_name_type">var_name</TD></TR>
<TR><TD PORT="reserved1_pos">2</TD><TD PORT="reserved1_size">2</TD><TD></TD><TD PORT="reserved1_type">reserved1</TD></TR>
</TABLE>>];
}
}
zx_spectrum_tap__seq:blocks_type -> block__seq [style=bold];
block__seq:header_type -> header__seq [style=bold];
header__seq:len_data_type -> block__seq:data_size [color="#404040"];
block__seq:len_block_type -> block__seq:headerless_data_size [color="#404040"];
header__seq:params_type -> header__seq_params_switch [style=bold];
header__seq_params_switch:case0 -> program_params__seq [style=bold];
header__seq_params_switch:case1 -> array_params__seq [style=bold];
header__seq_params_switch:case2 -> array_params__seq [style=bold];
header__seq_params_switch:case3 -> bytes_params__seq [style=bold];
header__seq:header_type_type -> header__seq:params_type [color="#404040"];
}