Amstrad speedlocks

General Speedlock loading system overview:

• The speedlock loading system, using 1 or more standard blocks.
• Following this is a short speedlock block which contains the loading information for the remaining blocks which comprise the main-program.
• Following this is one or more speedlock blocks

• Speedlock V1 style:
  • This starts with the standard clicking pilot, using the standard clicking pilot bit-rate.
  • Following this is a 6-bit code which is stored in the data bit-rate.
  • Following this are the data-bytes.
• Speedlock V2 and greater
  • This starts with the standard clicking pilot, using the standard clicking pilot bit-rate.
  • Following this is a 6-bit code (&1d) stored using the bit-rate of the data.
  • Following this are one or more data sub-blocks.

    Each block can be loaded to a different location and has a different length.

    The location and lengths of the blocks are either stored in the speedlock loader or in the first short speedlock block.

    The location and lengths are in a table form.

    The table has 5 entries:

    Offset	Length	Description
    0	2	Destination load address
    2	2	Length in bytes-1
    4	1	Unused (always &80)

    NOTES:

    • The load address and length of the first sub-block is not stored in the table.
    • The load address and length of the final (checksum?) block is not stored in the table.
    • If byte 0 of the entry is "0" then this is the end of the table. And this will automatically trigger the loading of the final checksum block.
  • between each sub-block is a set of 3 7-bit sequences (e.g. 0000000 0000000 0000000). The middle sequence must all be 1's (i.e. =&7f), otherwise the loading will fail.

  Normally there is a short speedlock v1 style block, stored with the same bit-rate as the main blocks. This block contains the furthur loading instructions for the remaining blocks in the main program.

  For speedlock V1, following this are one or more blocks containing screen and program code.

  For speedlock V2, following this is a large block containing screen and program code together.

  For some speedlocks, there are additional speedlock V1 style blocks after to load additional data (see Wizball).

  For some speedlocks there is more than one speedlock V1 style block before the speedlock V2 main block (see Tarzan).