September 2, 1992
              1990 Census of Population and Housing
                        Summary Tape File 3A

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                         Using The CD-ROM
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Some STF 3A State files require more than one CD-ROM.  When a State is split,
each CD-ROM contains small area summaries such as census tracts and block
groups for selected counties.  Each of the CD-ROMs for a State contains all
summaries for places, counties, and higher levels of census geography.

The 1990 Summary Tape File 3A software was designed to run on a personal
computer with 640K RAM operating under MS-DOS 3.0 or higher.  There are no
special display requirements.  The CD-ROM is in the ISO 9660 format which
requires the use of Microsoft CD-ROM Extensions Version 2.0 or higher.

The software displays some brief statistical definitions through the glossary
function.  Please refer to Appendix B of the technical documentation for the
complete text.

For direct access to the data files, one of the many software packages
which recognize the dBASE III Plus (.DBF) format will be very useful.

Users of other types of systems, such as the Apple Macintosh, have access
to the files through support for ISO 9660 CD-ROMs.  Please note that the
retrieval software will only run in the MS-DOS environment.

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                      Starting The Software
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Type GO at the DOS prompt and ENTER.  Example:  L:\>go

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                       Insufficient Memory
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If your computer system has less than 500K available RAM, you may have
insufficient memory for all software functions.

Type GO LITE at the DOS prompt and ENTER.  Example:  L:\>go lite

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                      Contents Of The CD-ROM
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Volume in drive is CD90_3A_ss

DOCUMENT <DIR> Directory for documentation files.  These are ASCII text files
               which contain the complete technical documentation for the data.
               See \DOCUMENT\HOWTOUSE.ASC for information on the contents of
               the files.

GO.BAT         Batch file to execute data retrieval software.

STF3A.EXE      Data retrieval software.

STF3LITE.EXE   Data retrieval software with reduced memory requirements.

STF3??ss.DBF   Statistical database files for each State. <ss> is the State
               abbreviation.  There are 35 files for each State numbered
               STF300ss.DBF through STF334ss.DBF

Reference Files

STF3STRU.DBF   This file describes the structure of the first 67 fields in the
               statistical database file.  These are the identification fields.

TABLES.DBF     This file describes the numeric data tables.

CNAMESss.DBF   This file lists county names and FIPS codes for State <ss>.


Index Files

CNAMESss.NDX   This is a dBASE III index file for CNAMESss.DBF.
               Key field is ANPSADPI.

STF3AMss.NDX   This is a dBASE III index file for STF300ss.DBF.
               Key fields are SUMLEV + CNTY + COUSUBFP + PLACEFP + TRACTBNA +
                              BLCKGR.

STF3APss.NDX   This is a dBASE III index file for STF300ss.DBF.
               Key fields are SUMLEV + PLACEFP.

STF3ATss.NDX   This is a dBASE III index file for STF300ss.DBF.
               Key fields are SUMLEV + CNTY + TRACTBNA + BLCKGR.

STF3ALss.NDX   This is a dBASE III index file for STF300ss.DBF.
               Key fields are SUMLEV + left(ANPSADPI,1).  This index is UNIQUE.

TABLES.NDX     This is a dBASE III index file for TABLES.DBF.
               Key fields are TABLE + FIELD.

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