BBC JIM Hardware I/O Addresses
                    ==============================

JIM should be used as a 256-byte window into external RAM expansion. In the
absence of this some hardware has used addresses in JIM.


FC40-4F Torch SASI/SCSI Hard Drive Access
=========================================
Addr  Write Action                      Read Action
--------------------------------------------------------------------
FDF0  Data Out                          Data In    
FDF1  Reset                             Status     
FDF2  Select 1                          Set ACK (SASI only)          
FDF3  Select 0                          -          


FDFE-FF Test vector
===================
FDFE                                    Test vector low byte
FDFF                                    Test vector high byte

If hardware on the 1MHz bus asserts IRQ on RESET it must provide a vector at
&FDFE/FF which will be jumped through after the RESET code has initialised
memory. Hardware can page memory into JIM with code in to execute.