1394 Questions & Answers
1394 Questions & Answers : GENERAL
Q. What is 1394?
A. 1394 is an IEEE standard for a high-speed, low cost
serial bus that has been developed by an IEEE committee. Among
other things, 1394 is designed to be a global interconnect, eliminating
the need for many different I/O interconnects resulting in port
integration and board space consolidation. This will result in a system-level
cost reduction.
Q. How does Apple fit in?
A. Apple wanted an open architecture, so they introduced their Firewire technology to the committee.
Q. Is the standard stable?
A. Yes, the standard was adopted by IEEE in December 1995. The hardware
portions had not been changed from the 8.0 v2 draft. The standard currently
specifies speeds of 100, 200 and 400 Mbits/second. There are efforts to create
speed improvements to 800 and multi-Gigabit speeds. For a copy of the IEEE approved
standard, it can be purchased from 
IEEE Standards Department,
specifying the 1394-1995 IEEE Standard for a High Performance Serial Bus,
420 pages [1-55937-583-3] [SH94364-NYF] Price: $90.00 IEEE Mbr: $63.00 and can
be ordered by calling (800)678-IEEE.
Q. Who is manufacturing the cable and connectors?
A. Molex, Hosiden, AMP, Stewart Connector and others.
Molex, Inc. Hosiden America Corp.
2222 Wellington Ct. 120 East State Parkway
Lisle, IL 60532 Scaumberg, IL 60173
708-969-4490 708-885-8870
Attn: S.Y. Theng Attn: Doug Riemer
Molex Worldwide Contacts:
Europe : H.T. Leong Ph: 31-40-258-3180
Japan : Shinichi Tadokoro Ph: 81-462-61-4500
S.E. Asia: Kok Whee Teo Ph: 65-268-6868
AMP Stewart Connector
P.O. Box 3608 R.O.2, Box 2020
MS 024-010 Glen Rock, PA
Harrisburg, PA 17105-3608 717-235-7512
Attn: David Hernjak Attn: Dave Hatch
Q. Are there any PC manufacturers with 1394 machines out on the
market?
A. Not at present. There are development activities within several pc manufacturers but it is expected to be late 1996 or early 1997 before we see machines out in the market. In general there is a lot of activity underway on 1394 but again we will probably not see evidence of this until late 1996.
Q. Are there any peripheral manufacturers (such as HDD's) who plan
to produce products featuring 1394?
A. Maxtor/Adaptec, Western Digital, and IBM Storage all showed
prototype HDD's at the COMDEX show in November 1993. It is likely none of these will go into production until the host systems manufacturers begin production of 1394/Firewire machines.
Q. What 1394 connector specifications are available?
A. The connector specifications are located in the IEEE 1394-1995 standard.
This document contains
both cable as well as connector mechanical drawings. For a copy of the IEEE approved
standard, it can be purchased from IEEE Standards Department,
specifying the 1394-1995 IEEE Standard for a High Performance Serial Bus,
420 pages [1-55937-583-3] [SH94364-NYF] Price: $90.00 IEEE Mbr: $63.00 and can
be ordered by calling (800)678-IEEE.
Q. Where can I find out general system level information on 1394?
A. The best information that is currently available regarding
system-level issues is the actual IEEE spec itself.
1394 Questions and Answers : DATA RATES/PERFORMANCE
Q. What is the maximum transmission rate?
A. 1394 is defined to support - 100, 200, and 400 m/bits per
second data throughput rates. The committee decided to define these speeds
up front so that future speed enhancements can be quickly implemented. There are efforts
to expand the standard to include 800 and multi-Gigabit speed improvements.
Q. Is the transfer rate of the 1394 scalable?
A. Yes, 100, 200, and 400 megabits per second nodes can all
be supported in the same topology.
Q. Will this require a different chip set for each speed?
A. Yes. However, since 1394 is dynamically designed, there is
no need to have every node operating at the same speed. If you add a
new node, the topology will reconfigure itself to incorporate the new node.
Q. The 1394 spec allows for a delay of up to 144ns/node, but
what delay does the TI chipset actually have?
A. Although our parts come in below the 144 ns/node spec, we cannot
say for certain what this number truly is. To account for s/c
process variations the parts are guardbanded, and so typically you
will see the delay down in the 130's. However, for the purposes of overall performance calculations, I believe that it is best to stick with the 144nS/node number.
Q. How does the sustainable bandwidth differ between isochronous
and asynchronous transactions?
A. The two major differences between the two types of transaction
which affect the sustained throughput are that isochronous transactions do not involve 'acknowledges' and isochronous gaps are of shorter duration than 'subaction gaps'.
1394 Questions & Answers : CABLE/CONNECTOR
Q. Is the shield connected to ground?
A. Yes, both the internal and external shield are connected to
ground.
Q. How many power lines are incorporated in 1394?
A. There are two power lines that are used in the 1394 cable.
Q. What type of cable is used with 1394?
A. It is a six wire, shielded twisted-pair cable.
Q. What 1394 connector specifications are available?
A. The connector specifications are located in the IEEE 1394-1995 standard.
This document contains
both cable as well as connector mechanical drawings. For a copy of the IEEE approved
standard, it can be purchased from IEEE Standards Department,
specifying the 1394-1995 IEEE Standard for a High Performance Serial Bus,
420 pages [1-55937-583-3] [SH94364-NYF] Price: $90.00 IEEE Mbr: $63.00 and can
be ordered by calling (800)678-IEEE.
1394 Questions & Answers : SYSTEMS/APPLICATIONS
Q. On the PC side, does it matter what internal bus you are using?
A. No, as long as an interface to the bus is present.
Q. What about a PCI bus?
A. You can take full advantage of 1394 by using this local bus.
At this time, it seems that PCI is the way most companies are going.
Both PCI and 1394 are emerging technologies and it makes sense to link
them together. Please see the Technical Overview
for more information on TI solutions for 1394 bus and PCI bus interconnection.
Q. Does 1394 have interactive video capability?
A. Yes
Q. Could 1394 be a cable to TV link with many other possibilities?
A. Yes, we now see many opportunities for utilizing 1394 that
we did not see initially. Also, 1394 will make a big difference in the
multimedia market by bringing the price down and providing many features
beneficial to this market.
Q. Can you connect a device to the PC while operating another unit?
A. Yes, and this is truly an advantage for the people interested
in a "plug-and-play" environment.
Q. Is 1394 multi-point - does it function like a bus?
A. No, 1394 is a point-to-point bus which has many characteristics
of a multi-point bus.
Q. Does a system require any other chips other than a Physical
Layer device such as TSB11C01 and a LINK layer controller such as the TSB12C01A to implement a system?
A. Not to implement, or be compliant to, 1394.
There will normally, however, be some logic needed to hook
these chips into the rest of the application or system. The requirement for
additional chips (in addition to the link layer and physical layer chips)
depends on the application. For example, one customer is using a 32-bit
processor to send & receive information from the FIFOs on the TSB12C01A
Link. Another possibility is to use a DSP such as the TMS320C52 to control
the link layer device. Please see the Technical Overview
for more information on TI solutions.
