TYPE_PCI1762
 };
 
-/* which I/O instructions to use */
-enum hw_io_access {
-       IO_8b, IO_16b
-};
-
 #define MAX_DI_SUBDEVS 2       /* max number of DI subdevices per card */
 #define MAX_DO_SUBDEVS 2       /* max number of DO subdevices per card */
 #define MAX_DIO_SUBDEVG        2       /* max number of DIO subdevices group per
        struct diosubd_data sdio[MAX_DIO_SUBDEVG];      /*  DIO 8255 chans */
        struct diosubd_data boardid;    /*  card supports board ID switch */
        unsigned long timer_regbase;
-       enum hw_io_access io_access;
+       unsigned int is_16bit:1;
 };
 
 static const struct dio_boardtype boardtypes[] = {
                .sdo[0]         = { 16, PCI1730_DO, 2, },
                .sdo[1]         = { 16, PCI1730_IDO, 2, },
                .boardid        = { 4, PCI173x_BOARDID, 1, },
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1733] = {
                .name           = "pci1733",
                .nsubdevs       = 2,
                .sdi[1]         = { 32, PCI1733_IDI, 4, },
                .boardid        = { 4, PCI173x_BOARDID, 1, },
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1734] = {
                .name           = "pci1734",
                .nsubdevs       = 2,
                .sdo[1]         = { 32, PCI1734_IDO, 4, },
                .boardid        = { 4, PCI173x_BOARDID, 1, },
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1735] = {
                .name           = "pci1735",
                .sdo[0]         = { 32, PCI1735_DO, 4, },
                .boardid        = { 4, PCI1735_BOARDID, 1, },
                .timer_regbase  = PCI1735_C8254,
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1736] = {
                .name           = "pci1736",
                .sdi[1]         = { 16, PCI1736_IDI, 2, },
                .sdo[1]         = { 16, PCI1736_IDO, 2, },
                .boardid        = { 4, PCI1736_BOARDID, 1, },
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1739] = {
                .name           = "pci1739",
                .cardtype       = TYPE_PCI1739,
                .nsubdevs       = 2,
                .sdio[0]        = { 48, PCI1739_DIO, 2, },
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1750] = {
                .name           = "pci1750",
                .nsubdevs       = 2,
                .sdi[1]         = { 16, PCI1750_IDI, 2, },
                .sdo[1]         = { 16, PCI1750_IDO, 2, },
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1751] = {
                .name           = "pci1751",
                .nsubdevs       = 3,
                .sdio[0]        = { 48, PCI1751_DIO, 2, },
                .timer_regbase  = PCI1751_CNT,
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1752] = {
                .name           = "pci1752",
                .sdo[0]         = { 32, PCI1752_IDO, 2, },
                .sdo[1]         = { 32, PCI1752_IDO2, 2, },
                .boardid        = { 4, PCI175x_BOARDID, 1, },
-               .io_access      = IO_16b,
+               .is_16bit       = 1,
        },
        [TYPE_PCI1753] = {
                .name           = "pci1753",
                .cardtype       = TYPE_PCI1753,
                .nsubdevs       = 4,
                .sdio[0]        = { 96, PCI1753_DIO, 4, },
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1753E] = {
                .name           = "pci1753e",
                .nsubdevs       = 8,
                .sdio[0]        = { 96, PCI1753_DIO, 4, },
                .sdio[1]        = { 96, PCI1753E_DIO, 4, },
-               .io_access      = IO_8b,
        },
        [TYPE_PCI1754] = {
                .name           = "pci1754",
                .sdi[0]         = { 32, PCI1754_IDI, 2, },
                .sdi[1]         = { 32, PCI1754_IDI2, 2, },
                .boardid        = { 4, PCI175x_BOARDID, 1, },
-               .io_access      = IO_16b,
+               .is_16bit       = 1,
        },
        [TYPE_PCI1756] = {
                .name           = "pci1756",
                .sdi[1]         = { 32, PCI1756_IDI, 2, },
                .sdo[1]         = { 32, PCI1756_IDO, 2, },
                .boardid        = { 4, PCI175x_BOARDID, 1, },
-               .io_access      = IO_16b,
+               .is_16bit       = 1,
        },
        [TYPE_PCI1762] = {
                .name           = "pci1762",
                .sdi[1]         = { 16, PCI1762_IDI, 1, },
                .sdo[1]         = { 16, PCI1762_RO, 1, },
                .boardid        = { 4, PCI1762_BOARDID, 1, },
-               .io_access      = IO_16b,
+               .is_16bit       = 1,
        },
 };
 
                        s->n_chan       = d->chans;
                        s->maxdata      = 1;
                        s->range_table  = &range_digital;
-                       switch (board->io_access) {
-                       case IO_8b:
-                               s->insn_bits    = pci_dio_insn_bits_di_b;
-                               break;
-                       case IO_16b:
-                               s->insn_bits    = pci_dio_insn_bits_di_w;
-                       break;
-                       }
+                       s->insn_bits    = board->is_16bit
+                                               ? pci_dio_insn_bits_di_w
+                                               : pci_dio_insn_bits_di_b;
                        s->private      = (void *)d;
                }
        }
                        s->n_chan       = d->chans;
                        s->maxdata      = 1;
                        s->range_table  = &range_digital;
-                       switch (board->io_access) {
-                       case IO_8b:
-                               s->insn_bits    = pci_dio_insn_bits_do_b;
-                               break;
-                       case IO_16b:
-                               s->insn_bits    = pci_dio_insn_bits_do_w;
-                               break;
-                       }
+                       s->insn_bits    = board->is_16bit
+                                               ? pci_dio_insn_bits_do_w
+                                               : pci_dio_insn_bits_do_b;
                        s->private      = (void *)d;
                }
        }
                s->n_chan       = d->chans;
                s->maxdata      = 1;
                s->range_table  = &range_digital;
-               switch (board->io_access) {
-               case IO_8b:
-                       s->insn_bits    = pci_dio_insn_bits_di_b;
-                       break;
-               case IO_16b:
-                       s->insn_bits    = pci_dio_insn_bits_di_w;
-               break;
-               }
+               s->insn_bits    = board->is_16bit ? pci_dio_insn_bits_di_w
+                                                 : pci_dio_insn_bits_di_b;
                s->private      = (void *)d;
        }