dBASE

dBASE is one of the earliest and most influential database management systems for microcomputers. Originally developed by Ashton-Tate in the late 1970s, dBASE pioneered the DBF file format and became the de facto standard for database applications on DOS and Windows.

What You Can Upload

• .DBF table files (dBASE III, IV and 5, and FoxPro tables)
• .DBT memo files, and .FPT memo files for FoxPro tables
• ZIP archive with complete file sets

What You Get Out

DataMeans converts your data into multiple modern formats:

Output	Description
csv/{TableName}.csv	One CSV file per table with all row data
xlsx/{TableName}.xlsx	Excel workbook per table (omitted for tables over 1,048,575 rows, 16,384 columns or 8,000,000 cells - see note below)
xls/{TableName}.xls	Legacy Excel format per table (omitted for tables over 65,535 rows, 256 columns or 150,000 cells - see note below)
json/{TableName}.json	JSON array of records per table
json/{TableName}.jsonl	Newline-delimited JSON (streaming-friendly)
postgres.sql	PostgreSQL CREATE TABLE + INSERT statements
mysql.sql	The same schema and rows, in MySQL dialect
sqlite.sql	The same schema and rows, in SQLite dialect
ansi.sql	The same schema and rows, in portable ANSI SQL
sqlserver.sql	The same schema and rows, in SQL Server (T-SQL) dialect
report.json	Structured conversion report
report.md	Human-readable conversion summary

How to Export / Obtain Files

1. Locate your dBASE application's data directory
2. Copy all .DBF table files
3. Include associated .DBT memo files
4. Create a ZIP with all files
5. Upload the ZIP to DataMeans

Supported Features

• Automatic version detection (III, IV, V)
• All standard field types: Character, Numeric, Logical, Date, Memo
• Extended field types: Float, Binary, Integer, General/OLE
• Character encoding from the table's language driver (code page) mark: the Windows and DOS code pages, Mazovia (Polish), Kamenický (Czech) and the Macintosh code pages
• A table whose mark names no code page is read as UTF-8 when its field names and text are valid UTF-8; otherwise in the code page of the origin you choose
• Memo field support (DBT format)

Known Limitations

• Index files (.NDX, .MDX) are not needed and not carried over
• dBASE 7 tables (the format of Visual dBASE 7 and dBASE PLUS) and dBASE II tables are not read yet: copy them to dBASE IV or dBASE III tables in dBASE first. The upload preview says so before you pay, and a job whose tables are all of these fails with that message; if only some are, the others are converted and the report names the ones that were not
• Catalog files (.CAT) are not read
• A table whose header states more records than the file holds (a download cut short, or a damaged file) is converted with the records the file holds; the upload preview and the job report say how many the header states and how many were read, and a complete copy is the way to get the rest
• A table with no code page mark and accented text in a legacy code page is read in the code page of the origin you choose, so choose the origin to match the system that wrote the file; the job report says when a code page was assumed
• OLE (General), Picture and Binary fields are delivered as their bytes, base64-encoded

Note on the Excel formats. An .xlsx sheet holds at most 1,048,575 rows of data and 16,384 columns, and a legacy .xls sheet 65,535 rows and 256 columns. Rather than ship a file that looks complete but is silently cut short, DataMeans leaves a table out of any Excel format it does not fit and notes it in the job report. The .xlsx copy is also left out for tables of more than 8,000,000 cells (1,048,575 rows of 12 columns is 12.6 million), which take too long and too much memory to write, and the .xls copy for tables of more than 150,000 cells, which the legacy format takes far too long to write. The CSV, JSON and SQL outputs always contain every row.

Overview

dBase is a classic database management system that pioneered the xBase family of databases. It uses a simple file-based architecture in which .dbf files contain tabular data, with indexes and memos stored in companion files. dBase popularized database concepts in microcomputing and influenced countless database systems, though it has largely been superseded by modern RDBMS.

History and Background

• 1978: Wayne Ratliff writes Vulcan, the database program that becomes dBase.
• 1980: Ashton-Tate licenses Vulcan and re-releases it as dBase II for CP/M.
• 1981: IBM commissions a port of dBase II; it is among the first programs available when the IBM PC ships that fall.
• 1984: dBase III, rewritten in C, is released.
• 1986: dBase III PLUS adds LAN multi-user support and the menu-driven Assist interface.
• 1988: dBase IV major release with SQL support.
• 1990: A U.S. federal court dismisses Ashton-Tate's copyright suit against Fox Software, ruling that dBase derived in part from the public-domain JPLDIS.
• 1991: Borland acquires Ashton-Tate.
• 1993: Borland releases dBASE IV 2.0 for DOS.
• 1994: Borland releases dBase 5.0 for DOS and Windows.
• 1999: Borland sells the dBase product line to KSoft, Inc., later renamed dBASE Inc.
• Present: Legacy systems still in use; the product line continues as dBASE PLUS.

File Format Specifications

dBase uses a simple file-based structure with separate files for data, indexes, and memos.

DBF File (.dbf):

• Binary format with header and data records
• Header: 32-byte structure followed by field descriptors
• Records: Fixed-length with field data
• File extension: .dbf
• Maximum fields: 128 (dBASE III), 255 (dBASE IV and later)
• Maximum record size: 4,000 bytes (dBASE III and IV)

Index Files (.ndx, .mdx):

• B-tree structure for fast lookups
• Single-field indexes (.ndx)
• Multiple indexes (.mdx)
• Support for compound keys

Header Structure:

• First byte indicates dBASE version
• Bytes 1-3: Last update date (YYMMDD)
• Bytes 4-7: Number of records
• Bytes 8-9: Header length
• Bytes 10-11: Record length
• Byte 15: Encryption flag
• Byte 29: Language driver ID
• Field descriptors follow header
• Each descriptor is 32 bytes: name (bytes 0-10), type (byte 11), length (byte 16), decimal count (byte 17)
• Level 7 widens descriptors to 48 bytes with 32-byte field names
• Header ends with 0x0D byte
• Data section ends with a 0x1A end-of-file marker

Associated Files:

• .ndx: Single index files
• .mdx: Multiple index files (dBASE IV and later)
• .dbt: Memo field storage (dBASE III and later)
• .fpt: Memo field storage (FoxPro compatible)
• Memo data is stored in 512-byte blocks in dBASE III; dBASE IV makes the block size configurable (default 512)

Data Types and Structures

Type Code	Type	Size	Description
C	Character	Variable	Text strings, space-padded
N	Numeric	Variable	Numbers stored as ASCII text
F	Float	Variable	Floating-point numbers stored as ASCII text
I	Integer	4 bytes	Binary long integers (Level 7)
D	Date	8 bytes	Dates in YYYYMMDD format
L	Logical	1 byte	Boolean (T/F/Y/N)
M	Memo	10 bytes	Pointer to memo file block
B	Binary	10 bytes	Binary data in memo file
G	OLE	10 bytes	OLE objects in memo file
+	Autoincrement	4 bytes	Auto-incrementing long integers (Level 7)
O	Double	8 bytes	Binary floating-point numbers (Level 7)
@	Timestamp	8 bytes	Two long integers storing date and time (Level 7)

Database Structure:

• Tables consist of fixed-length records
• Fields defined in header with name, type, length, decimal places
• Records contain field data in order
• Deleted records marked with '*' in first byte
• Indexes provide fast lookup and sorting
• Memo fields store large text/binary data externally

Version Differences

Version	Year	Key Features	File Format Level
dBASE II	1980	First widely used microcomputer DBMS	Level 2: 16-bit record count, 32-field limit
dBASE III	1984	Rewritten in C; memo fields	Transitional format; .dbt memo files
dBASE III PLUS	1986	LAN multi-user support, Assist menus	Level 3
dBASE IV	1988	SQL support, Control Center	Level 4: .mdx indexes, 255-field limit
dBASE IV 2.0	1993	Performance-focused Borland release for DOS	Level 4 (no format change)
dBASE 5.0	1994	Editions for DOS and Windows	Level 5
Visual dBASE 5.5	1995	Visual designers for Windows 3.1/95	Level 5 (no format change)
Visual dBASE 7	1997	32-bit release for Windows 95/NT	Level 7: 31-character field names

Compatibility Notes:

• The dBASE III-era format is the most widely supported by third-party applications
• Level 7 files are incompatible with readers supporting only earlier levels
• Character encoding varies between OEM and ANSI code pages, identified by a language driver ID in the header
• Field count and size limits increased over versions
• Some applications support only subset of data types
• The ESRI shapefile format requires a dBASE-format .dbf file as its attribute table
• LibreOffice Calc and Base open and save .dbf files, though formulas and formatting are not preserved

Technical References

• dBASE Table File Format (DBF)
• dBASE .DBF File Structure
• Wikipedia: .dbf
• DBF File Format Description
• Xbase File Format Description