Changes
<font size="-2:>''Copyright Amstrad ©1990 plc''</font></center>
''Note: this text is not the original document as published by Amstrad; instead, Executioner and Arnoldemu has corrected some (or all?) of the mistakes found thereinand added additional clarification. For the original document, look [[Arnold_V_specs|here]], for more original documents see: [[Original Arnold V Specs]].
When the following I/O ranges are read 7fxx, bcxx, bdxx, efxx and dfxx (these are write-only I/O registers), the last byte of the I/O read instruction is put onto the bus and read. e.g. if IN A,(C) is used to read from one of these ports, the last byte of that instruction is read back.
There is no hardware that is driving these registers, so the data is effectively "floating"what is last on the z80 data bus.
===Reading of unmapped ASIC register RAM===
When a read of an unmapped address is done from the ASIC register page (this is where there is no readable register here, or no register has been assigned), the last byte of the instruction used to do the read is return. e.g. if LD A,(&5000) is done, the last byte of this instruction is then read.
There is no hardware that is driving these registers, so the data is effectively "floating"what is last on the z80 data bus.
===Power requirements===
