NEC NEAX Sigma Magnetic Tape Emulation


The NEC NEAX Sigma or NEC NEAX Ʃ as it is sometimes written, is a development following on from the NEAX 61E/BR series. NEAX stands for Nippon Electric Automated Exchange and refers to fully-automated and electronic (rather than electro-mechanical) nature of the exchange.

The SIgma is significantly newer in terms of technology, but builds on the success of the NEAX 61 series. 

Installed Base

The NEAX Sigma was mostly installed in Japan. Some other installations exist in Asia and South America but it was not as widely deployed as the NEAX 61E and variants.


The Sigma makes use of DAT tape drives for backup purposes. The DAT drives are a more advanced (and smaller) type of tape drive from those used in the NEAX 61E. Therefore NEC NEAX Sigma Magnetic Tape Emulationrequires a slightly higher speed SCSI-like interface.

The Sigma is unusal in that the DAT drive typically shares the same SCSI bus as the Sigma's hard disk. This means that the SCSI bus is often quite busy with other data traffic even during a tape backup. This creates challenges for the tape emulation technology since the timing is very different depending on the load on the Sigma's main CPU and other operations running on the peripherals. With DDS we have spent considerable time perfecting our NEC NEAX Sigma Magnetic Tape Emulation implementation to avoid these issues.


The NEAX Sigma uses a DAT drive connector which is quite unusual. It includes both power and data on a single 68-pin centronics connector. We have developed an adaptor cable for this to allow the DDS to replace the DAT drive. A mounting kit is also available.

With the adaptor cable, installation is quite straightforward and the small size of the DDS makes it relatively easy to find space in the rack for the replacement equipment.

Data can be copied from the legacy DAT drives to the DDS easily using the tape-to-tape copy command, while connecting both the DAT drive and DDS to the exchange. The DDS SCSI ID can be adjusted on the on-screen menu to achieve this. SCSI termination features can be adjusted depending on the installation requirements.

The DDS can be installed without adjusting the software in the Sigma exchange. There is also no need to install additional interface cards or software to make use of the DDS. It is a plug and play installation.


Some training is required for installation since the adaptor cable must be fitted and replaces the existing DAT drive cable. This is not a dificult process but does require some basic knowledge of connectors and components within the DAT assembly.

Our local partner will provide advise and we will typically schedule 1-2 days of training to give engineers the grounding they need to complete installation. This training includes information on setting up special features available in the DDSsuch as multiple virtual tapes and the ability to control the DDS entirely from a remote site over a secure network.


Our experienced engineers are available for post-homologation and installation support. This is typically provided through our local partner in your country. For billing and mediation setup, we can advise on methods to achieve a fully-automated network setup with DDS's NEC NEAX Sigma Magnetic Tape Emulation providing the means to move billing data from the exchange to the billing system without user intervention.