I am one of the ``old'' supercomputer folks who has become a regular reader of BYTE. In fact, my product development references currently include your magazine. The subscription has paid for itself a number of times in 1 1/2 years. Dinah McNutt's article ``SCSI and Beyond'' (August) was excellent. At least 90 percent of BYTE articles have been outstanding--they are for the general audience of PC-o-philes but still do not ``write down'' and are therefore interesting and informative to me and mine.
Philip D. Tannenbaum
Director of Product Planning
HNSX Supercomputers, Inc.
The Woodlands, TX
In the article ``SCSI and Beyond,'' Dinah McNutt writes, ``SCSI uses a 3-bit addressing scheme.'' I just want to clarify that SCSI actually uses 8-bit addressing. Each device uses the bit number of its SCSI ID as
its address line. This is extremely important to understand for the arbitration bus phase. A device will assert its address line if it wants to acquire the bus. If more than one device wants the bus, the device with the highest address will win. Multiple IDs are accommodated by the wired OR logic used on the SCSI bus.
Steven Krapp
Software Engineer, Motorola
Schaumburg, IL
I agree with you, and I did state that ``SCSI is an 8-bit parallel I/O bus.'' Electrically, all 8 bits are being used. However, for the purposes of installing devices on the bus, you have a 3-bit address space. As you say, it is a matter of clarification (for the hard core).
--Dinah McNutt
The Intricacies of SCSI Addressing
