PRB: F1901 Error - Long Variable List in EQUIVALENCE Statement

• Microsoft FORTRAN for MS-DOS, versions 4.01, 4.1, 5.0, 5.1
• Microsoft FORTRAN for OS/2, versions 4.1, 5.0, 5.1

SYMPTOMS

An attempt to compile an application fails and the compiler generates the following message:

   F1901: program too large for memory

CAUSE

The application uses an EQUIVALENCE statement that contains a very large list of variables. The FORTRAN compile stores data in the near heap. If the data exhausts the available space, the F1901 error occurs.

RESOLUTION

To avoid this problem, use the high-capacity FORTRAN compiler to free memory in the near heap. The high-capacity FORTRAN compiler is provided with FORTRAN version 5.0 and later.

FORTRAN PowerStation can handle the example code in this article.

STATUS

This behavior is by design in FORTRAN. It is a restriction in the FORTRAN compiler as documented in Appendix C of the FORTRAN "Reference" manual for version 5.1 (page 409).

MORE INFORMATION

To use the high-capacity compiler, copy the F1L.EXE file from the FORTRAN 5.0 High-Capacity Compiler Disk into the FORTRAN BIN directory (by default, C:\FORTRAN\BIN). Modify the compiler command line to specify the /B1 compiler option switch and the path to the high-capacity compiler. For example, to compile the TEST.FOR source file with the high-capacity compiler located in the default directory, use the following command line:

   FL /B1 C:\FORTRAN\BIN\F1L.EXE TEST.FOR

Sample Code

C Compile options needed: None

      IMPLICIT REAL*8 (A-Z)
      EQUIVALENCE
     +(A1, B1),   (C1, D1),   (E1, F1),
     +(A2, B2),   (C2, D2),   (E2, F2),
     +(A3, B3),   (C3, D3),   (E3, F3),
     +(A4, B4),   (C4, D4),   (E4, F4),
     +(A5, B5),   (C5, D5),   (E5, F5),
     +(A6, B6),   (C6, D6),   (E6, F6),
     +(A7, B7),   (C7, D7),   (E7, F7),
     +(A8, B8),   (C8, D8),   (E8, F8),
     +(A9, B9),   (C9, D9),   (E9, F9),
     +(A10, B10), (C10, D10), (E10, F10),
     +(A11, B11), (C11, D11), (E11, F11),
     +(A12, B12), (C12, D12), (E12, F12),
     +(A13, B13), (C13, D13), (E13, F13),
     +(A14, B14), (C14, D14), (E14, F14),
     +(A15, B15), (C15, D15), (E15, F15),
     +(A16, B16), (C16, D16), (E16, F16),
     +(A17, B17), (C17, D17), (E17, F17),
     +(A18, B18), (C18, D18), (E18, F18),
     +(A19, B19), (C19, D19), (E19, F19),
     +(A20, B20), (C20, D20), (E20, F20),
     +(A21, B21), (C21, D21), (E21, F21),
     +(A22, B22), (C22, D22), (E22, F22),
     +(A23, B23), (C23, D23), (E23, F23),
     +(A24, B24), (C24, D24), (E24, F24),
     +(A25, B25), (C25, D25), (E25, F25),
     +(A26, B26), (C26, D26), (E26, F26),
     +(A27, B27), (C27, D27), (E27, F27),
     +(A28, B28), (C28, D28), (E28, F28),
     +(A29, B29), (C29, D29), (E29, F29),
     +(A30, B30), (C30, D30), (E30, F30),
     +(A31, B31), (C31, D31), (E31, F31),
     +(A32, B32), (C32, D32), (E32, F32),
     +(A33, B33), (C33, D33), (E33, F33),
     +(A34, B34), (C34, D34), (E34, F34),
     +(A35, B35), (C35, D35), (E35, F35),
     +(A36, B36), (C36, D36), (E36, F36),
     +(A37, B37), (C37, D37), (E37, F37),
     +(A38, B38), (C38, D38), (E38, F38),
     +(A39, B39), (C39, D39), (E39, F39),
     +(A40, B40), (C40, D40), (E40, F40),
     +(A41, B41), (C41, D41), (E41, F41),
     +(A42, B42), (C42, D42), (E42, F42),
     +(A43, B43), (C43, D43), (E43, F43),
     +(A44, B44), (C44, D44), (E44, F44),
     +(A45, B45), (C45, D45), (E45, F45),
     +(A46, B46), (C46, D46), (E46, F46),
     +(A47, B47), (C47, D47), (E47, F47),
     +(A48, B48), (C48, D48), (E48, F48),
     +(A49, B49), (C49, D49), (E49, F49),
     +(A50, B50), (C50, D50), (E50, F50),
     +(A51, B51), (C51, D51), (E51, F51),
     +(A52, B52), (C52, D52), (E52, F52),
     +(A53, B53), (C53, D53), (E53, F53),
     +(A43, B43), (C43, D43), (E43, F43),
     +(A44, B44), (C44, D44), (E44, F44),
     +(A45, B45), (C45, D45), (E45, F45),
     +(A46, B46), (C46, D46), (E46, F46),
     +(A47, B47), (C47, D47), (E47, F47),
     +(A48, B48), (C48, D48), (E48, F48),
     +(A49, B49), (C49, D49), (E49, F49),
     +(A50, B50), (C50, D50), (E50, F50),
     +(A51, B51), (C51, D51), (E51, F51),
     +(A52, B52), (C52, D52), (E52, F52),
     +(A53, B53), (C53, D53), (E53, F53),
     +(A54, B54), (C54, D54), (E54, F54),
     +(A55, B55), (C55, D55), (E55, F55),
     +(A56, B56), (C56, D56), (E56, F56),
     +(A57, B57), (C57, D57), (E57, F57),
     +(A58, B58), (C58, D58), (E58, F58),
     +(A59, B59), (C59, D59), (E59, F59),
     +(A60, B60), (C60, D60), (E60, F60),
     +(A61, B61), (C61, D61), (E61, F61),
     +(A62, B62), (C62, D62), (E62, F62),
     +(A63, B63), (C63, D63), (E63, F63),
     +(A64, B64), (C64, D64), (E64, F64)
      END