NAME

description of file format used by z80-mon for bank layout

DESCRIPTION

The file compounds of lines each is either a comment line or a bank- or a page description. A comment line starts with a # and may appear anywhere in the file. A line containing a bank description consists of the following 4 entries: access_type bank_id log2_size bank_name. A line containing a page description consists of these 4 entries: either offset or bank_id followed by port_no mask and a non empty list of bank_ids.

All bank description lines must preceed the page description lines and must be ordered ascending by their unique bank_id. The following page description lines are ordered ascending by their first item which is typically an offset or in the case of a virtuel bank a bank_id. If lines have the same first entry then they must be ordered ascending by their port_id with - regarded less than any other port_id. And in the case even their second entries equals each other, then these lines will be ordered by their mask. A list of bank_ids is an ascending sequence of bank_ids separated only by , (comma), not any whitespace.

access_type
is the type of the bank. Only the four types + for
read/write memory, r for read only memory, w for write
only memory and - for a virtuel bank are valid.

bank_id
is a 2 digit hexadecimal byte value.

log2_size
gives the size of the bank in bytes as its log2-value.
Currently only banks whose log2_size equals 14 (16 kB)
or 12 (4 kB) are supported. Due to hardware complexity
all banks must have currently the same size!

bank_name
must either indicate a readable file which contains the
machine code for the bank or the special value - (minus)
which indicates either undefined storage, typically RAM,
or in the case of a virtuel bank no file name. If the corres-
sponding file is smaller than the bank size the remaining
bytes at the end of the bank will be undefined. If the file
size is larger than the bank size only the first bytes in
the file will be used.

offset
is a 4 digit hexadecimal value telling the hardware the
start address the bank to be mapped on. Furthermore
each offset must be a multiple of 1<<log2_size of the
bank size it can be mapped to.

port_no
is a decimal or hexadecimal number of value < 256 or
the character - (minus). In the second case the
following mask must be 0.

mask
is a 2 digit hexadecimal byte value which covers the relevant
part of value send to the corresponding port. The port_no
together with the given mask must have a unique offset
respectively bank_id.

Each used bank_id in a page description must be defined in a previous bank description. Summarizing, this file describes how the banks are mapped to memory or other (virtuel) banks. If a byte value is put to a port which has a corresponding page description then a mapping occurs if the bank_id matches the value and-ed with the mask of the port. Therefore page description lines with the same port_no should have different bank_id s for a unique mapping. The default bank_id of a page is the one with the lowest bank_id. This is selected at hardware initialisation and after a bank reset.

SEE ALSO

z80-memory(5)