Tape File Formats

Now we will describe some tape file formats (used to store and retrieve games in the C64) using low level details and also with 6510 Assembly language programs. These type of formats are describe because the emulator is able to manage them.

Commodore Kernal Format
Turbo Format
Galadriel Format
Golden Format 1
Golden Format 2

The format is describe using a common scheme:

Describe the type of bits used by in the format
Describe a byte structure (with eventually coding information)
Describe the synchronization region and the countdown sequence
Describe header and file structure
Final comments and considerations
Eventual assembly listing

Note that the assembly listing has a fixed structure, where there's present:

The address of the location
The byte of opcode + eventually bytes of instruction
The disassembly mnemonic instruction
A comment of instruction

The comment can be color to see that:

example this is automatic generated comment
example this is a comment human added to show the situation
example this is a comment for routine call
example this is a comment for routine definition
example this is a comment for the value of data

In this table there's a reassume of the information that you can read below (remember that the time provided are estimated, not measured).

Method	used bits	parity bit	Byte length (bits)	Copy present	Byte Duration (ms)	Byte per second	Time for 10Kbyte
Kernal	3	yes	20	2	20,4	49	7'
Golden 1	2	no	8	1	10,41	96	1'46"
Turbo	2	no	8	1	5,44	183	55"
Galadriel	2	no	8	1	4,21	237	43"
Golden 2	2	no	8	1	4,21	237	43"

Commodore Kernal Format

This is the format used by the Commodore 64 to store programs and data and it is already described in the previous page.

Bits:

L: ^^^°°°
H: ^^^^°°°°
*: ^^^^^°°°°°
Average time for HL: 2*996 micro sec
Average time for H*: 2*1243micro sec

Byte:

*H x0 x1 x2 x3 x4 x5 x6 x7 yy a byte
*L end of file

x0..x7 are HL for bit 1 and LH for 0 like in a Manchester coding.
yy is a parity bit (01 has 0 parity, 11 has 1 parity)

The effective byte is the decode of x7..x0, because low bit is the first.

Synchronization region:

a big region of 0 bits (this region may occupies 2/3 tour of tape)
89h, 88h, 87h, 86h, 85h, 84h, 83h, 82h, 81h for first copy
09h, 08h, 07h, 06h, 05h, 04h, 03h, 02h, 01h for second copy

Header and File:

The header and the file are stored in 2 copies. The file has a synchronization region like the header because when the header is found, the tape is stopped for displaying the file name, so a new synchronization may be used.

The header contains these information (1 word is low, high byte):

1 byte: Type of header (01h, 03, 04)
1 word: Start of program in memory
1 word: End of program in memory
10h bytes: File name
9Fh bytes: Header body (normally 20h)
1 bytes: Checksum of header (simple xor method)

The file contains these information:

File length bytes: Body of file
1 bytes: Checksum of file (simple xor method)

Comment:

The Kernal archive format is more reliable but too much slow!

Byte Average Length: always 1 '*', 10 'H', 9 'L'
Byte Average Times duration: 2*1243+18*996= 20,414 milli sec
Byte per second: 1/0,0204=49
Time for 10Kbyte: 10240*2/49=418" = 7'

Listing:

No listing is available. See the Kernal listing for the implementation of the method (that use interrupt for reading/writing).

Turbo Format

Galadriel Format

This is the format used by Galadriel Software to read the games with fast mode.

Bits:

0: ^^^°°°
1: ^^^^°°°°
Average time for 0/1: 526 micro sec.

Byte:

x7 x6 x5 x4 x3 x2 x1 x0

x0..x7 are the 0/1 bits. The byte is x7..x0 because low bit is the last.

Synchronization region:

a region of 02h bytes
10h, 09h, 08h, 07h, 06h, 05h, 04h, 03h, 02h, 01h

(Header and) File:

The file contains these information:

File length bytes: body of file
1 bytes: Checksum of file (simple xor method)

Comment:

This is a very quickly tape method but with no parity bit and only with one checksum!

Byte Average Length: 4 '0', 4 '1'
Byte Average Time duration: 8*526=4,208 milli sec.
Bytes per second: 1/0,004208=237,64
Time for 10Kbytes: 10240/237,64=43,08 sec.

Listing:

See the listing

Golden Format 1

This is the format 1 used by Golden Software to read the games with fast mode.

Bits:

0: ^^^°°°
1: ^^^^°°°°
Average time for 0/1: 768 micro sec.

Byte:

x0 x1 x2 x3 x4 x5 x6 x7

x0..x7 are the 0/1 bits. The byte is x7..x0 because low bit is the first.

Synchronization region:

a region of 02h bytes
52h, 42h

(Header and) File:

The file contains these information:

2 bytes: starting address of program
2 bytes: ending address of program
File length bytes: body of file
1 bytes:Checksum of file (simple xor method)

Comment:

This is a quickly tape method, but with no parity bit and only with one checksum!

Byte Average Length: 4 '0', 4 '1'
Byte Average Time duration: 8*768=10,416 milli sec.
Bytes per second: 1/0,010416=96
Time for 10Kbytes: 10240/96=106,66 sec. = 1'46"

Listing:

See the listing

Golden Format 2

This is the format 2 used by Golden Software to read the games with fast mode.

Bits:

0: ^^^°°°
1: ^^^^°°°°
Average time for 0/1: 526 micro sec.

Byte:

x7 x6 x5 x4 x3 x2 x1 x0

x0..x7 are the 0/1 bits. The byte is x7..x0 because low bit is the last.

Synchronization region:

a region of 02h bytes
09h, 08h, 07h, 06h, 05h, 04h, 03h, 02h, 01h

(Header and) File:

The file contains these information:

2 bytes: starting address of program
2 bytes: ending address of program
2 bytes: return address
File length bytes: body of file

Comment:

This is a very quickly tape method but with no parity bit and no checksum!

Byte Average Length: 4 '0', 4 '1'
Byte Average Time duration: 8*526=4,208 milli sec.
Bytes per second: 1/0,004208=237,64
Time for 10Kbytes: 10240/237,64=43,08 sec.

Listing:

See the listing

commodore 64

Tognon Stefano programs