Piped record `header' files allow application programs to
read signals from the standard input, or write them to the standard
output. Record `8' specifies 8-bit format, a 10-bit ADC, zero ADC
offset, and two signals sampled at 250 Hz, both of which are to be
acquired from the standard input, or written to the standard output.
Record `16' specifies 16-bit format and a 12-bit ADC, and is
otherwise identical to record `8'. ADCs from several manufacturers
can produce output in the format specified by record `16'; thus
such output can be piped directly into an application program using
record `16'. Signal files in AHA format also match these
specifications. Piped records for reading or writing other numbers of
signals also exist; they are named `8xn' and
`16xn', where n is the number of signals (n = 1,
2, ..., DB_MAXSIG).
Application programs may also read or write signal files in the current
directory using local record `header' files. Record
`16l' ("one-six-ell") specifies up to DB_MAXSIG format 16
files, and record `8l' ("eight-ell") specifies up to
DB_MAXSIG format 8 files, named `data0', `data1',
`data2', ..., `datan' in the current directory.
When opened using isigopen or dbinit, these signal files
will be readable by getvec as signals 0, 1, 2, ... n
respectively. These files should be created by the user, with the use
of putvec. It is necessary to create only as many signal files
as will be used; if, for example, only one signal is needed, only
`data0' need be created.
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