[E3-hacking] E1

[Ralph Corderoy]

Hi David,

> But nothing seems to come out. I need a scope.
> 
> It might be waiting for some sort of passkey, although this seems a
> little unlikely. If so, though, our only options are either hope that
> some nice person from Amstrad tells us what it is, or else to build a
> JTAG adaptor and extract the ROM...

I suspect it's more primitive than the E2's PBL so I doubt a passkey is
required.  Request 00 always replies with a NAK in PBL V3.1 but perhaps
it does something useful in the earlier version and was changed to be a
constant NAK later?  Do you get anything from request 01?

    PBL V3.1 Build:1277 EXP packet format
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

        Offset  Size  Value  Name   Description
          0       1     2    stx    ASCII STX byte.
          1       1    0/1   comp   Is `data' compressed.
          2       2     -    len    Length of data.
          4      len    -    data   Payload.
        4+len     1     -    cksum  Sum modulo 0x100 of bytes in len and data.

    First byte of payload gives message type.

    Payload requests
    ~~~~~~~~~~~~~~~~

    Contents of data in received packet.  First two bytes given request
    number.  Reply is request_number | 0x80 if all went well, or a NAK reply
    otherwise.

        Request: 00
            Not used.
        Reply: 15
            NAK message, sent to indicate disagreement.

        Request: 01 00
            Set 0x1001c = 0x01 to remember request 01 received.
        Reply: 81 00

Cheers,


Ralph.