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PC4B/50
ADF for PC4B/50

   The PC4 interface controller is an Iomega proprietary controller, not a SCSI controller. The PC4B will not support third party SCSI devices. The PC4B interface kit includes the 37 to 50 pin SCSI cable, OAD for DOS drivers, and Utility Users Manual. The PC4B controller may also be use with the OS/2, Unix, and Xenix operating systems. Addition drivers will be needed for any operating system other than DOS. 
   The PC4B controller will not have any configurable jumpers or switches for installation. All features of this controller are configured with the IBM Option Diskette that comes with the IBM computer. IBM models 90 and 95 must have a hard drive installed before the PC4B controller will function. 

   If your computer has a fixed disk drive, the fixed disk drive should be used to boot your computer. The ROM on the Iomega PC2B or PC4B adapter should be disabled.

I/O Address Select
   I/O address used by PC4B/50
      <"240" (io 00240h-0025Fh)>, 340 (0340-035F), 400 (0400-041F), 420 (0420-043F), 3240 (3240-325F), 8240 (8240-825F), A240 (A240-A25F), Disabled

DMA Level Select
   The PC4 supports the direct memory access (DMA) mode of data
transfer.  Most operating systems require this option to be
enabled.  Each DMA level has a corresponding priority level;
the lower the DMA level, the higher the corresponding priority.
      <"DMA Level 5">, 6, 7, DMA Disabled

Fairness
   If 'Fairness' is enabled, the PC4 adapter will not compete for the channel during the next arbitration phase if it is currently in control of the channel.  This allows other installed adapters to obtain the channel in the next sequence based on each adapter's assigned priority level.  When 'Fairness' is disabled, the adapter will compete for every arbitration phase and will obtain more than its fair share of channel usage. 
      <"Fairness Enabled">, Fairness Disabled

IRQ level
   Operation with multi-tasking operating systems may require the use of an IRQ signal when the PC4 requires processor service. No other adapter may be assigned the same IRQ level as the PC4. For DOS-only systems, this option may be disabled. 
      <"IRQ 7">, 5, 3, 9, IRQ Disabled

Memory Address Select
   You may set the PC4 adapter to any one of the Memory Addresses
listed.  The first choice is recommended for systems with a fixed
disk installed. 
      < "Disabled">, D400 (d400-d5ff), D200 (d200-d3ff), D000 (d000-d1ff), CE00 (ce00-cfff), CC00 (cc00-cdff), CA00 (ca00-cbff), C800 (c800-c9ff)