drears@pica.army.mil (Dennis G. Rears (FSAC)) (03/23/91)
I am moving and got some questions about my new telephone service. I will be getting two lines with circular hunting (circular just in case I get more lines installed). They are letting me have one line with touch tone and the other line without. Am I correct in assuming that touch tone only applies to dialing and not the sending of the tones after the connection is made? All of may phones are switchable to either touch tone and pulse. I found out my new service will be serviced by a 1ESS switch. Can anybody explain the difference between that and a 5ESS switch? I would really appreciate it if somebody could detail what each switch capability is. I agreed to have it billed on one number. The installation is $42 & $16 for the second line, for a total of $58. If I wanted two billing numbers it would have cost $42 and $42. That seems unreasonable to me. ($42 seems unreasonable to me for one line when you consider it is a $15 hookup charge for electric and $14 for gas). Dennis
john@zygot.ati.com (John Higdon) (03/24/91)
"Dennis G. Rears (FSAC)" <drears@pica.army.mil> writes: > I found out my new service will be serviced by a 1ESS switch. Can > anybody explain the difference between that and a 5ESS switch? I > would really appreciate it if somebody could detail what each switch > capability is. The 1ESS is the original Electronic Switching System. It is archaic. It is essentially an electronically controlled mechanical switch. The processor is slow and the memory is small and as a result its feature offering is deficient. It does not have enough feature store for SS7 and hence cannot provide CLASS features. Its Call Waiting cannot be temporarily cancelled (not enough room for CCW in the feature store). The 1AESS is the mid-seventies enhancement of the 1E. It uses a much more capable processor, a greatly expanded (and faster) memory, and a rich feature offering, although it is still analog. It can offer all features, including CLASS and its feature implementation is considered industry standard. To the ear, it sounds identical to the old 1E and cannot be differentiated in that manner. (A good test is whether or not Cancel Call Waiting is available.) The 5ESS is AT&T's current flagship switch. It is fully digital and offers or will eventually offer every single CO switch feature known to mankind. It does ISDN, CLASS, everything. It has lousy three-way calling compared to either the 1ESS or the 1AESS, but you cannot have everything. It's three-way is better than a DMS100 without the proper hardware/software packages, however. I am told that someday (no one knows when) all the crossbar in my CO will all be replaced with a 5ESS. Couldn't help but be an improvement. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@zygot.ati.com | San Jose, CA 95150 | M o o !
rees@pisa.citi.umich.edu (Jim Rees) (03/26/91)
In article <telecom11.230.7@eecs.nwu.edu>, drears@pica.army.mil (Dennis G. Rears (FSAC)) writes: > I found out my new service will be serviced by a 1ESS switch. Can > anybody explain the difference between that and a 5ESS switch? The 5ESS is the HAL-9000 of telephone switches, doing its work in complete silence. The one in our CO handles about a dozen prefixes, and is half the size of the 1ESS next to it that only handles three prefixes. The 1ESS has relays in it, not to do the actual switching, but to switch ringing voltage and the like on to the loop. It makes a lot of noise, although nothing like a panel office! The 5 is "modern" and will do SS7 things like Caller*ID. The 1 only does the basics, like Call Waiting. The 5 is digital, the 1 analog. The 5 has no moving parts in the actual switching circuitry. What I'd like to know is what are 2 and 3ESS? What's the difference between a 1 and a 1A (is it just the processor? Does 1A run Unix?) And what kind of hardware does a 4ESS have (I've never seen one)? > ($42 seems unreasonable to me for one line when you consider it is a > $15 hookup charge for electric and $14 for gas). Most installations only require a table change at the CO, but some may require actual field work (ask Patrick about the multiples on the cables in his neighborhood some time). The electric and gas companies don't have to do anything except turn on the billing usually, and if they do, they charge extra for it (they wanted $10k to bring 3-phase into my garage for my IBM System/3).
richarbm@mentor.cc.purdue.edu (Bryan Richardson) (03/26/91)
In article <telecom11.240.4@eecs.nwu.edu> rees@citi.umich.edu (Jim Rees) writes: X-Telecom-Digest: Volume 11, Issue 240, Message 4 of 11 > What I'd like to know is what are 2 and 3ESS? What's the difference > between a 1 and a 1A (is it just the processor? Does 1A run Unix?) > And what kind of hardware does a 4ESS have (I've never seen one)? I can't address 2 and 3ESS, but as a part of the 4 ESS software development organization, I can address the last question. The 4 ESS currently uses the same processor (the 1A) as the 1A ESS switch, but the 4E uses a digital switching fabric while the 1A is analog. In a live office, the 4E sounds similar to a 5E -- very little actual noise -- although it looks rather different (there are no doors on most of the frames). Bryan Richardson richarbm@mentor.cc.purdue.edu AT&T Bell Laboratories and, for 1991, Purdue University Disclaimer: Neither AT&T nor Purdue are responsible for my opinions.
goldstein@delni.enet.dec.com (Fred R. Goldstein) (03/27/91)
In article <telecom11.240.4@eecs.nwu.edu>, rees@pisa.citi.umich.edu (Jim Rees) writes... > The 1ESS has relays in it, not to do the actual switching, > but to switch ringing voltage and the like on to the loop. It makes a > lot of noise, although nothing like a panel office! The 1ESS (and the 1A, which uses a less antiquated processor) uses reed relays to do the actual switching. They're vacuum-sealed, so they're quieter than the old ones. I suspect that the 1 can do Caller ID too, though Im not sure. > What I'd like to know is what are 2 and 3ESS? What's the difference > between a 1 and a 1A (is it just the processor? Does 1A run Unix?) > And what kind of hardware does a 4ESS have (I've never seen one)? The 2BESS is a "suburban" office, built in the '70s to early '80s, using (I think) reed relays like a 1A. It is basically a scaled down version of the 1A, with a different processor. The 3ESS is a very small analog office, of which very few were built (ca. 1980). The 1 uses an antique CPU with ferrite sheet EPROMs and mag cores. The 1A goes to semiconductor memory. As someone else noted, the 4ESS is a different beast, a big digital toll switch. Fred R. Goldstein Digital Equipment Corp., Littleton MA goldstein@delni.enet.dec.com voice: +1 508 486 7388 Do you think anyone else on the planet would share my opinions, let alone a multi-billion dollar corporation?
varney@ihlpf.att.com (Al L Varney) (03/27/91)
Well, this will be brief, since it's from memory; I've rearranged the previous discussion order somewhat. If you really MUST have more info., read the back issues of the Bell System Technical Journals. At least one issue was devoted to each switch. First, the obligatory note: ESS(tm) is a trademark of AT&T and 5ESS(tm) is a registered trademark of AT&T. The proper names are: 1 ESS Switch 1A ESS Switch 4 ESS Switch 5ESS Switch but I will use the obvious abbreviations below. In article <telecom11.243.8@eecs.nwu.edu> goldstein@delni.enet.dec.com (Fred R. Goldstein) writes: > In article <telecom11.240.4@eecs.nwu.edu>, rees@pisa.citi.umich.edu > (Jim Rees) writes... >> The 1ESS has relays in it, not to do the actual switching, >> but to switch ringing voltage and the like on to the loop. It makes a >> lot of noise, although nothing like a panel office! > The 1ESS (and the 1A, which uses a less antiquated processor) uses > reed relays to do the actual switching. They're vacuum-sealed, so > they're quieter than the old ones. I suspect that the 1 can do Caller > ID too, though Im not sure. > The 1 uses an antique CPU with ferrite sheet EPROMs and mag cores. The No. 1 ESS Switch indeed uses sealed relays for the switching fabric, but "reed relays" ??? Nope. The actual T/R path is through magnetic-latching relays, surrounded with some metal and a coil. Pulse the coil one way, the contacts close and REMEMBER to stay closed. Pulse the other way, the contacts open and REMEMBER to stay that way. No current is used to maintain either position. They are the size of a Christmas tree bulb and make little noise. The traffic-dependent noise you hear is the "wire-spring" relays that exist in the remainder of the switch, primarily in the Trunk/Junctor circuits. The 1E "CPU" consists of about 10 feet of circuits in a standard seven foot high "bay", arranged across from it's "mate" CPU. The CPUs run in lock- step, comparing results of every instruction. The memory is separate; for programs high office data, "EPROM" memory is formed from ferrite spots stuck to 6X12(?) inch sheets of aluminum. Typical office might have 40 feet of such memory, duplicated. Temporary (writable) memory is usually mag cores (32K by 23 bits + 1 parity per two foot bay). Program memory words are 37 bits wide, with an added 8 bits for Hamming-code parity (I believe automatic single-bit error correction is in the hardware). Architecture could be called "early RISC, messy" -- most instructions are one cycle or 5.5 microseconds. Capacity is roughly 35K lines. >> What's the difference between a 1 and a 1A (is it just the processor? >> Does 1A run Unix?) > The 1A goes to semiconductor memory. No. 1A ESS Switches use the same switching fabric as 1E. The circa 1973 processor is two CPUs in a six-foot wide frame, running in lock-step. Program and temporary memory are on separate busses, but look identical. Most modern version of memory puts 14 256K-by-14-bit units in a three-foot bay -- max of two bays per office allows at most four Mwords (12 Mbytes). Instruction set vaguely resembles an orthoganal version of 1E, with a typical instruction (24 or 48 bits wide) taking .7 milliseconds. Many shift/rotate/mask/insert options could be used, without added time, due to a complete 48-bit "barrel" shifter. For comparison, "clock speed" is 20 MHz; even though memory bus is 20 feet long, 700 nanoseconds can do a 48-bit read or 24-bit write. An overlapping dual-parity scheme is used on each memory word. Disk backup is used, with about 10 Mwords available. Original disk drives used 26(?) inch platters, with 100 fixed heads on each side, thus no seek overhead. Existing switches handle 90K lines. No fans in either 1E or 1A equipment, just ambient cooling. UNIX (also tm) grew up about the same time as 1A, but really !!! You don't switch 300K calls per hour on a non-MMU machine with UNIX. The OS is really a task dispenser with routines voluntarily giving up control every two or three milliseconds (sort of like Multi-Finder, no?). Much polling and processing takes place on a timed interrupt level, forced every five milliseconds. No other interrupts occur normally. >> What I'd like to know is what are 2 and 3ESS? > The 2BESS is a "suburban" office, built in the '70s to early '80s, > using (I think) reed relays like a 1A. It is basically a scaled down > version of the 1A, with a different processor. No. 2 ESS existed in 1968, so it's really scaled down from 1E. Every- thing was redesigned from the ground up, so there is essentially no shared circuitry with 1E. The processor was "strange". A 22 bit instruction word with one "long" 21 bit instruction or two 10-bit instructions; the remaining bit was = 1 only on words where transfers of control were expected to arrive. A bit-twiddlers toy. 10K lines?? (The processor was also used to drive the "Automatic Intercept System" [AIS], the one that says "The number you have reached, nyen-nyen-one-pause-six-six-six-six has been changed. The new ...". This was my first project with AT&T.) No. 2B ESS Switch was just a re-worked version of the No. 3 ESS processor with mico-code interpreting the original 2E instructions (but faster than the original hardware). I believe it gave a 50%+ increase in capacity. > The 3ESS is a very small analog office, of which very few were built > (ca. 1980). Don't know numbers, but there were quite a few in more "rural" areas. The "3A" processor -- no relation to the "3B" line -- was small and fast. I believe this was the first to use mico-code; 1E/1A/4E/2E don't. Don't know much else, except a whole office could fit in a semi-trailer (with MDF!) for emergency use. Several were tested on the trailer, shipped and then slid into place with attached air pallets. >> And what kind of hardware does a 4ESS have (I've never seen one)? > As someone else noted, the 4ESS is a different beast, a big digital > toll switch. Well, actually a Tandem switch, but BIG anyway. Same processor as 1A, with a totally digital switch. These are rated at 100K Trunks, 600K+ calls/hour. There was also (past tense, I believe) the No. 101 ESS switch, an early PBX. This used a processor from another project, with a unique PAM fabric (pulse amplitude modulation). Essentially, every line/trunk had an appearance on a single wire, with a different combination connected at an 8KHz rate. This allowed noise-less switching and many connections to a single line/trunk without loading problems. This same fabric was used in AIS, to allow many people to listen to "six" at the same time. "Six" was a single trunk connected to a repeating .5 second recording. Adjusting the volume on those trunks was boring!! Oh, oh, another long article. Maybe I'll do 5ESS later, Pat. In closing, I've had the pleasure of programming all of these switches except the No. 3 ESS switch. They all had something worth learning as far as designing to a particular goal. In most cases, the capacity of the switch drove the design. Al Varney, AT&T, Lisle, IL
rcj1@ihlpf.att.com (Raymond C Jender) (03/29/91)
In article <telecom11.230.7@eecs.nwu.edu>, drears@pica.army.mil (Dennis G. Rears (FSAC)) writes: > What I'd like to know is what are 2 and 3ESS? What's the difference > between a 1 and a 1A (is it just the processor? Does 1A run Unix?) > And what kind of hardware does a 4ESS have (I've never seen one)? The 2 and 3ESS are smaller rural type switches. Sorry, I don't know much more then that without researching. The 1 and 1A differ in the processor used. The 1E uses an analog processor. The 1A Processor is digital. Both 1E and 1A use the same network, thus when a 1E is being retrofitted to 1A, only the processor is swapped out. That the reason that the calls sound exactly the same on both switches, they only complete quicker. No, the 1A does not run Unix, or any other popular brand of OS. It uses it's own proprietary and unique assembly language. The 4E uses the 1A processor. It's network is digital. It can be used as either a Toll or Tandem switch. I guess you can say there was a completely digital switch being used back in, oh, when did the first 4E cut over, 1975-78 time frame?
varney@ihlpf.att.com (Al L Varney) (04/01/91)
Oops! Some corrections: In article <telecom11.246.5@eecs.nwu.edu> varney@ihlpf.att.com (Al "Oops" Varney) writes: > [In other articles, Fred R. Goldstein and Jim Rees write:] Fred> The 1ESS has relays in it, not to do the actual switching, Fred> but to switch ringing voltage and the like on to the loop. It makes a Fred> lot of noise, although nothing like a panel office! This is correct, in the sense that the "switches" are not "relays". Jim> The 1ESS (and the 1A, which uses a less antiquated processor) uses Jim> reed relays to do the actual switching. They're vacuum-sealed, so Jim> they're quieter than the old ones. I suspect that the 1 can do Caller Jim> ID too, though Im not sure. > The No. 1 ESS Switch indeed uses sealed relays for the switching But I meant to say "reed switch" here ^^^^^^ > fabric, but "reed relays" ??? Nope. The actual T/R path is through > magnetic-latching relays, surrounded with some metal and a coil. ^^^^^^ ...and here > Pulse the coil one way, the contacts close and REMEMBER to stay > closed. Pulse the other way, the contacts open and REMEMBER to stay > that way. No current is used to maintain either position. I E-mailed a better explanation to Jim, but in summary, the reason I disagreed about the term "reed relay" was because of the word "relay"; but then I used it myself (Ooof)! They are "switches" because they do not actually switch a current based on another current or pulse. They are switched "dry" (sans current); the contacts can't be cleaned and will stick or weld shut if switched "wet" frequently. Therefore, external relays to trunks and lines must be used to remove battery/ ground before setting up a path through the network. A matrix of switch crosspoints is arranged so that closing a tip/ring crosspoint in a matrix automatically opens all the other pairs in the same X row and Y column. When a path is "released", it's X and Y matrix points are marked idle, but the crosspoints remain closed until some other action selects another crosspoint in the same X row or Y column. Further errata: > Instruction set vaguely resembles an orthoganal version of 1E, with No "Freudian" jokes, please... it's ^^^^^^^^^^ "orthogonal". > a typical instruction (24 or 48 bits wide) taking .7 milliseconds. let's try "microseconds", eh? ^^^^^^^^^^^^ >Al Varney, AT&T, Lisle, IL You really ought to read the stuff before you publish, dum-dum. Al