3922 Parallel Bus Crate Controller



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The Model 3922 is a double-width CAMAC crate controller that connects to the associated computer interface card via a parallel bus. When used with the Model 2926, 2927, or 2928 interface card, the combination forms a computer-based CAMAC system with an IBM PC/AT reg.or PS/2® or compatible processor as the host. The Model 2922 interface card can also be used with the 3922 to form a DIGITAL Q-bus-based CAMAC system. A Macintosh II host is interfaced using the Model 2932, any VME-based computer is interfaced using the Model 2917, and PCIbus systems can utilize the 2915 PCI adapter.

Up to eight 3922s can be addressed on the interface bus. The crate address (0 through 7) is selected by a front-panel switch. A single 40-wire ribbon cable is connected to the computer interface card and looped-through the crate controllers. Interface bus connections are made at the rear of each 3922. The last 3922 terminates the bus. RS-485 balanced-line signaling is used on the interface bus to allow reliable operation with up to 91 meters (300 feet) of total bus length. Twisted-pair, flat-ribbon bus cable enhances data integrity The eight-bit interface bus is multiplexed for address and data transfer. Appropriate control/response signals are also included.

The 3922 supports the DMA capabilities of the 2922, 2926, 2927, and 2928 adapters. Sixteen-bit DMA data is transferred at rates up to 1 Mbyte/s for the Model 2922, and 250 kbyte/s for the 2926, 800 kbyte/s for the 2927, and 500 kbyte/s for the 2928. Block transfers are supported when interfacing to a computer with the 2917 VME adapter, 2932 Macintosh II adapter, or our newest addition: the 2915 PCI adapter.

A 24-bit LAM mask is included to simplify the host software. A “Selected LAM Present” causes a service request to the computer interface. A parallel poll is per formed to determine which 3922s are requesting service.

This module is configured at the factory as a mail crate controller. It can be changed in the field to function as an auxiliary crate controller. An additional 40-contact, rear-panel connector is then used for the Auxiliary Controller Bus.


Command             Q             Description

F(1)A(0)   RD2   On-line   Reads Control/Status register
F(1)A(12)  RD2   On-line   Reads LAM Pattern
F(1)A(13)  RD2   On-line   Reads LAM Mask
F(17)A(0)  WT2   On-line   Writes Control/Status register
F(17)A(13) WT2   On-line   Write LAM Mask
  1. X = 1 for all valid addressed commands.
  2. Q = 1 for all valid addressed commands when the 3922 is set on-line by the front-panel switch.

+ 6 volts — 3.3 A

Weight: 1.2 kg (2 lb. 9 oz.)


Model 3922-Z1B — Parallel Bus Crate Controller (replaced the Model 3922-Z1A)


Model 5843-Txyz — Twisted-pair, Flat-ribbon Cable Assembly (required)
Model 2915-Z1A — PCIbus Interface
(See also Sparrow's Kmax* software support)
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Model 2917-Z1A — VME Interface
Model 2922-Z1B — Q-bus Adapter
Model 2926-Z1A — IBM PC Interface with DMA
Model 2927-Z1A — IBM PC/AT Interface with DMA
Model 2928-Z1A — IBM PS/2 Interface
Model 2932-Z1A — Macintosh II Interface

™Q-bus, RSX-11, and VMS are trademarks of Digital Equipment Corporation.
™Macintosh II is a trademark of Apple Computer, Inc.
®IBM PC/AT and PS/2 are registered trademarks of IBM Corporation