.TH CDL 10.6
.ds CD \s-2CDL\s0
.SH NAME
cdl \- circuit description language
.PD .2i
.ds or \fP\ |\ \fB
.SH DESCRIPTION
The circuit descriptions used by the various circuit design aid programs
are expressed in dialects of \*(CD \(em the circuit design language described below.
This is half of a complete project specification; namely
an electrical circuit with chips, pins and connecting signals.
The other half, a physical layout with pins and chip positions, is described in
.IR fizz (10.6)
format.
The commands described below are recommended;
others exist and may work but are regarded as obsolete.
.sp
.PP
.SS Logic design
.PP
A circuit consists of
.I chips
connected by
.I signals.
The point of connection is denoted by a
.I pin.
Each chip has a
.I type
which describes its logical and electrical
characteristics.
(For example,
.B 74S181
is a chip type.)
.PP
Types, signals, and chips are identified by name.
Pins  are identified by name and number.
A
.I name
is a string of letters,
digits, or any of the characters
.BR +-.$/:<=>[]_ .
Sometimes, the first character
may not be a digit.
A name may not be longer than 16 characters.
.PP
In the following description,
literals appear as
.B constantwidth
and names are in
.I italic.
[ ] enclose an optional item and
a list of items is written
.IP
.RI { item }
.PP
Commands are separated by either newline or
semi-colon.
A comment
starts with a
.B %
and ends with a newline
and may appear on any line.
All white space serves only to separate tokens.
.SS General
.B .f
[
.I file
]
.br
Subsequent input originated in
.I file .
If
.I file
is not present, the previous file name is restored.
.PP
.B .q
.br
End of file.
.SS Signal Description
.I signal
[
.I pin-number
] [ [
.I ,
]
.I pin-name
]
.br
.I name
=
.I signal
.br
Lines that do not start with a period are signal
definition lines.
Signal definitions refer to the most recent
.B .c
command.  The pin name and number refer to the chip.
.SS Circuit Description
.B .c
.I name
[ [
.B ,
]
.I type
]
.br
Instantiates the chip
.I name
with type
.I type.
This is typically used for I/O connectors.
The command may occur more than once.
The
.I type
of a chip need only be specified
once in a circuit description.
Signal descriptions that follow
a
.B .c
command refer to pins on the chip.
.PP
.ne 10
.B .c
.I name
.B =
.I chip
.br
Establish
.I name
as a synonym for the previously defined
.IR chip .
.PP
.B .m
.I name1 name2
.br
Macro parameter definition.
The signal
.I name1
is to be associated with macro parameter
.I name2.
.SS Chip Type Description
.B .t
.I name package
.RI [ pin ]\ ...
.br
Define a chip type
.I name.
The name of the
.I package
in which it is installed,
and pin numbers,
.I pin,
for the special signal connections
are specified.
The special voltage
pin numbers, if present, must be in the same
sequence with which the special signals are numbered.
This usage is discouraged;
use the
.BR .t [ tT ]
commands described below.
(See
.B .v
command.)
All commands of the form
.BR .t ?
are meant to follow a
.B .t
line.
.PP
.B .t
.I name
.B =
.I type
.br
.I name
is a synonym for
.I type .
.PP
.BI .tt \ sequence_of_single_character_pin_descriptors
.br
The number of characters must equal the numbers of pins on this
.IR type .
The meaning of the descriptors is given in
.IR smoke (10.1).
.PP
.BI .tT \ sequence_of_single_character_pin_descriptors
.br
This means the same as the equivalent
.B .tt
command except that every
.B [gvwxyz]
pin must have a corresponding
.B .vb
pin.
.PP
.B .tp
.I name
.I number
\&...
.br
The given
pin
.I name
is associated with the pin
.I number.
.I Name
may contain generators such as
.B Q[0-7]
which cause pin names
.B Q0
.B \&...
.B Q7
to be assigned to the pin numbers given.
Multiple bracket constructs may be used.
In any case, the resulting list is lexicographically sorted before
assigning to pin numbers.
.SH SEE ALSO
.I cdm (10.1)