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Volume 3, Number 51 29 December 1986 +---------------------------------------------------------------+ | _ | | / \ | | /|oo \ | | - FidoNews - (_| /_) | | _`@/_ \ _ | | International | | \ \\ | | FidoNet Association | (*) | \ )) | | Newsletter ______ |__U__| / \// | | / FIDO \ _//|| _\ / | | (________) (_/(_|(____/ | | (jm) | +---------------------------------------------------------------+ Editor in Chief: Thom Henderson Chief Procrastinator Emeritus: Tom Jennings FidoNews is the official newsletter of the International FidoNet Association, and is published weekly by SEAdog Leader, node 1/1. You are encouraged to submit articles for publication in FidoNews. Article submission standards are contained in the file ARTSPEC.DOC, available from node 1/1. Copyright (C) 1986, by the International FidoNet Association. All rights reserved. Duplication and/or distribution permitted for noncommercial purposes only. For use in other circumstances, please contact IFNA. Table of Contents 1. ARTICLES Managing a Major Network Reorganisation INVITATION TO JOIN A NEW ECHO CONFERENCE - "SOFTWARE CAREERS" Western New York Net formed 2. COLUMNS What is Baud Rate 3. WANTED Writer wanted 4. FOR SALE Magazine On Disk for IBM PC and Compatibles DISCACHE V0.01 Buy some MIDI for Christmas!! 5. NOTICES The Interrupt Stack LAPTOP echomail BBS for Whisper Reader/LEX-31 owners Fidonews Page 2 29 Dec 1986 ================================================================= ARTICLES ================================================================= Gary Stern, 155/214 [620/301] Bill Bolton, 155/219 [620,403] Managing a Major Network Reorganisation One of the most frustrating things about being involved in a "remote" Fido network is finding out how other nets have solved problems in the past. Somehow or other we manage to struggle along here on the bottom of the world, often I fear re-inventing the Fido wheel. Occasionally we come across something that another net has taken the trouble to document, such as the SOCAL echomail policy document ECHO-102. Even though this document was way out of date when I got it, it shed light into several dim areas of echomail and gave us some idea of what should be done. In this light I am submitting the documentation on the Great Australian Network Changeover to FidoNews, in the knowlege that someone else in the Fido community, either now or sometime in the future is sure to need to do the same sort of thing again. I'd also like to say thank you VERY much to Jon Sabol, 1/112, who turned a spoltlight into many dark recesses of echomail for me. Bill Bolton PREPARING YOUR SYSTEM FOR THE GREAT AUSNET CHANGEOVER ----------------------------- By Gary Stern and Bill Bolton Network 155 in Region 12 will soon cease to exist and will be replaced by four new networks, Nets 620, 626, 630 and 690 in Region 50. You will need to make some changes to your system to accommodate the new networks. The way we will pass mail around the network is also changing. This document will tell you what you need to do to be ready for changeover day, December 7th. IF YOU ARE RUNNING FIDO ONLY ---------------------------- Fido users will need these files: 1. XLATLIST.600 Sample control file. 2. ROUTEGEN.60X Sample Control files. 3. AUS_ECHO.ARC New echomail files. IF YOU ARE RUNNING FIDO + SEADOG -------------------------------- Fido systems that are also running SEADOG will need an Fidonews Page 3 29 Dec 1986 additional file: 4. PARTCDOG.600 Sample sections of SEAdog files. WHERE TO GET THE FILES ---------------------- The files probably wont be ready at the same time that this document gets distributed but should be ready within a day or two. A message advising where to get them will follow shortly. READ IT ALL! ------------ It doesn't matter what you are running, you should read the whole document before doing anything. BEFORE THE CHANGEOVER --------------------- On or before December 1st, 1986. 1) Close down the sending of echomail from your node as soon as you receive this document. This is done by disabling all SCANMAIL invocation lines in your RUNBBS batch files. Then you must edit your AREAS.BBS to remove all forwarding nodes. You should continue to run TOSSMAIL after all mail events so that any echomail still in the mail system that is delivered to you will be tossed to the correct area. 2) While this point is not policy, you should consider raising the level of access to your FidoNet MAIL area to sysop privilege only, until after the changeover. This will avoid users sending out mail to other nodes with "soon to be invalid" return addresses. When we change, the old net numbers will disappear out of the nodelist plus your individual node within your new net might be different. Also if you have mail from your system still IN TRANSIT anywhere in the network (maybe overseas) when the nodelist with the new node numbers becomes effective, the transiting node will immediately ORPHAN your messages which means they will never be delivered. AT THE TIME TO CHANGEOVER ------------------------- At 1200 hrs (midday) on Sunday, December 7, 1986: You should have received NODEDIFF.A39 in the morning mail Fidonews Page 4 29 Dec 1986 schedule. In a perfect world that would be all you would receive, however since we haven't had to do a changeover like this previously you may also receive some final instructions so please check your mail on that day. 1) Check NODEDIFF.339 with an editor or just type it out, just to make sure the changes have been done. You will find that Australia is now in Region 3 which should be well down toward the end of the file. If for some reason it isn't there or you haven't received NODEDIFF.A39, DO NOT MAKE ANY FURTHER CHANGES. Ring your Network Co-ordinator for information. 2) You will have to modify the new XLATLIST.CTL file distributed with this document. You need to insert your new Node Number. If you have any BAUD or PHONE statements applying to Net 155 nodes statements in your present XLATLIST.CTL, these need to added and also modified to reflect the new network addresses. Finally you'll need to modify the cost table in the new file to suit your location! If you are a hub or a host, please carefully read the special instructions in the XLATLIST.CTL file. 3) ROUTEGEN.CTL must be modified. If you will be in Net 620 you can use the ROUTEGEN.620 file after renaming it to ROUTEGEN.CTL. If you are in Net 626 use ROUTEGEN.626, if in Net 630 use ROUTEGEN.630 and if in Net 690 use ROUTEGN.690. You only have to insert your new NODE number. You should delete all existing ROUTE.* files before running Routegen. 4) Before running XLATLIST you must go into Fido and use the SYSOP "4" command to reset your Net and Node numbers. You MUST reset your Net/Node numbers before you run XLATLIST. If you are also a HUB or a HOST you MUST set your Net and Node number in Fido to your normal node identity. You should set your Alternate Node number to your hub or host identity. You MUST NOT put your hub or host identity as your primary node number. 5) Run XLATLIST and invoke Fido to compile its new nodelist. 6) Modify your RUNBBS.BAT (or SEADOG.BAT) file to cover the new mail arrangements and external events as detailed below. 7) Put your system back on line. NEW MAIL ARRANGEMENTS --------------------- Fidonews Page 5 29 Dec 1986 Fido doesn't use daylight saving times and will not refer to them in this document. If you have trouble converting between Australian Eastern Standard Time and daylight saving time, buy yourself a cheap digital watch (they just about give them away now) and leave it set to Australian Eastern Standard time. You should then be able to get the times right! The Australian National Mail Hour will run from 0400 to 0500 Australian Eastern Standard Time, 0330 to 0430 Australian Central Standard Time and 0200 to 0300 Australian Western Standard Time. IF YOU ARE IN NET 626, 630 or 690 --------------------------------- Nets 626, 630 and 690 will send mail to their hosts for 25 minutes, starting 30 minutes before the national mail hour using Schedule-G. Starting 5 minutes after the national mail hour, nodes will poll their host to pickup mail for 25 minutes using Schedule-W. IF YOU ARE IN NET 620 AND ARE A LOCAL NODE ------------------------------------------ Net 620 is more complicated as it running three hubs. The local nodes will send mail to their hubs for 10 minutes using Schedule-H, starting 30 minutes before the national mail hour and ending 20 minutes before the national mail hour. The local nodes will send any mail not addressed to the nodes on their hub, and which was not able to be delivered to their hub (perhaps due to a failure), to the outgate for 10 minutes using Schedule-G, starting 15 minutes before the national mail hour and ending 5 minutes before the national mail hour. After the national mail hour the local nodes will be in a receive only mode for 20 minutes using Schedule-V. This is followed by 10 minutes where the local nodes poll their hub for received mail using Schedule-W. IF YOU ARE IN NET 620 AND ARE A HUB ----------------------------------- The Hubs will receive mail from their local nodes for 10 minutes using Schedule-H, starting 30 minutes before the national mail hour and ending 20 minutes before the national mail hour. This is followed by 5 minutes to process the received mail. Hubs will then send any network mail to the outgate for 10 minutes using Schedule-G, starting 15 minutes before the national mail hour and ending 5 minutes before the national mail hour. The hubs will receive mail from the outgate for 10 minutes using Schedule-V, starting 5 minutes after the national mail hour and ending 15 minutes after the national mail hour. This is Fidonews Page 6 29 Dec 1986 followed by a 5 minutes to process the received mail. For 10 minutes, commencing 20 minutes after the national mail hour, the hub is polled by its local nodes to pickup received mail, using Schedule-W. The 5 minutes between the schedules before and after the national mail hour are for the hubs to run arcmail (from), tossmail, scanmail and arcmail (to). MAIL TIMETABLE FOR HUBBED NETWORK --------------------------------- The following timetable shows what each stage in a three tiered mail network (node, hub, outgate) in region 50 does during national mail processing. Time Node Hub Outgate --------------------------------------------------------- 0325 Process mail Do nothing Do nothing 0330 Send to hub Receive from Do nothing nodes 0340 Do nothing Process mail Do nothing 0345 Do nothing Send to Receive from unless hub outgate hubs down then send to outgate 0355 Do Nothing Do nothing Process mail 0400 Direct mail Direct Mail Poll hosts if required if required for mail 0425 Direct mail Direct Mail Process mail if required if required 0430 Direct Mail Direct Mail Send to hosts if required if required 0500 Do Nothing Receive from Send to hubs outgate 0515 Do Nothing Process mail Do nothing 0520 Poll hub Hubs hold mail Do nothing for mail 0530 Do nothing Do nothing Do nothing 0535 Process Mail Do nothing Do nothing Fidonews Page 7 29 Dec 1986 MAIL TIMETABLE FOR HOST NETWORK ------------------------------- The following timetable shows what each stage in a two tiered mail network (node, host) in Region 50 does during national mail processing. Time Node Host ------------------------------------------ 0325 Process mail Do nothing 0330 Send to host Receive from nodes 0355 Do nothing Process mail 0400 Direct mail Hold for pickup if required by outgate 0425 Direct mail Do nothing if required 0430 Direct Mail Receive from if required outgate 0500 Do Nothing Process mail 0505 Poll host Hold mail for for mail nodes 0530 Do nothing Do nothing 0535 Process Mail Do nothing ECHOMAIL -------- All echomail will be shut down prior to the changeover. New software will be distributed to all nodes and echomail conferences will be reintroduced, one at a time. To speed mail processing, ARCMAIL is being introduced. ARCMAIL has a dramatic effect on the handling of all mail, but especially echomail and will allow us to expand the number of echomail conferences that can be supported by the network. Nodes will run an external event commencing an adequate time prior to their first morning mail period, we recommend at least 5 minutes before the mail period. This event will include TOSSMAIL to clear any mail echomail left in the net mail message area for the previous mail time, SCANMAIL to place new echomail messages from the node into the net mail area and ARCMAIL to pack the messages for sending. Fidonews Page 8 29 Dec 1986 Similarly, an adequate time after the morning mail period, nodes will run another external event, again we recommend 5 minutes after the end of the mail period to ensure any mail transmissions have finished. This event will run ARCMAIL to unpack messages and TOSSMAIL to clear echomail messages from the net mail areas into the appropriate conference areas. You may optionally want to renumber or otherwise process received messages at this stage. ECHOMAIL CONFERENCES -------------------- The first echomail conference that will be started is a new one for the Australian FidoNet Association. This will be followed by AUST_SYSOP etc. at a later date. You will be advised when other conferences will individually commence. The reason for re-starting echomail with a new conference is to simplify the initial testing of the new echomail routing structure. When the existing conferences are re-started you will need to do a lot of work with the SEENBY and SETMARKS commands to prepare your echomail areas. Instructions on what to do will be issued separately once we have the AFNA conference running satisfactorily. Please note that you must use the new echomail files contained in AUS_ECHO.ARC. The other conferences will not be restarted until everyone is using the same versions of echomail software. You will need to create a system message area for the AFNA conference and then edit AREAS.BBS to enter the AFNA message area number and the conference name AUST_FNA. ECHOMAIL HANDLING ----------------- Local nodes will only forward echomail to their hubs or hosts. Hubs or hosts will only forward echomail to their local nodes plus the outgate. The following are examples of entries in the AREAS.BBS files for various nodes: HUB 500 ------- 20 AUST_FNA 620/200 620/502 620/503 620/504 620/505 This hub has the AFNA conference is message area 20 and forwards it to his local nodes 620/502....620/505 and to the outgate 620/200 Node 502 -------- Fidonews Page 9 29 Dec 1986 10 AUST_FNA 620/500 This node has the AFNA conference in message area 10 and forwards it to his hub, 620/500 only. Hubs will still receive messages intended for them as nodes because echomail knows about alternate node numbers. That's why its important that your hub or host number be the alternate node identity and not the primary one. Using the same examples here are the sort of command lines which should appear in your RUNBBS batch files:- HUB 500 before Schedule-G and after Schedule-V ---------------------------------------------- arcmail from 620/200 620/502 620/503 620/504 620/505 tossmail run -stats scanmail run -nopriv -stats arcmail to 620/200 620/502 620/503 620/504 620/505 The hub runs the same event for all mail processing. Before Schedule-G the hub unARCs mail received from its local nodes and tosses any echomail into the appropriate areas. It then scans echomail areas for outbound messages, including any echomail messages originating from the hub. It then ARCs all mail destined for the outgate and nodes. Any messages originating on the hub and destined for the local nodes are ARCed but will remain in the net mail message area for the time being. After Schedule-V the hub unARCs any mail received from the outgate and tosses any echomail into the appropriate areas. It then scans echomail areas for outbound messages and places them in the network file area. Any messages for the local nodes are then ARCed or possibly added to an existing ARCed packet for the node that was prepared after Schedule-G. Note that before Schedule-G there would normally be no mail from the outgate to be processed, only mail from the nodes. Similarly after Schedule-V there is normally no mail from the nodes to be processed, only mail from the outgate. NODE 502 before and after morning mail period --------------------------------------------- arcmail from 620/500 tossmail run -stats scanmail run -nopriv -stats arcmail to 620/500 The node runs the same event for all mail processing. Fidonews Page 10 29 Dec 1986 Before the mail period the node tosses any echomail messages that may have been accidently left in the net mail message area from the previous mail time. It then scans the echomail message areas for outbound messages. All mail for the hub is then ARCed. After the mail period the node unARCs any mail received from the hub and tosses echomail into the appropriate message areas. To assist in developing a traffic analysis of the network we are asking all sysops to log statistical information on their echomail traffic, hence the use of the "-stats" option on tossmail and scanmail. Please keep archives of these logs as we will be asking you to forward them so we can get on with the traffic analysis. The ECHOMSGS.LOG generated by the "-stats" does not contain any information about the content of the messages or who sent them, only information on the number of messages processed out of each echomail area. To assist in keeping private mail out of echomail conferences we want you to use the "-nopriv" option with scanmail. This will stop private "junk" echomail from cluttering up echomail conference areas. As ARCMAIL uses a external program to do the ARCing you must make sure that it is accessible to ARCMAIL by having it in the same directory or otherwise accessible through a PATH statement in DOS. OTHER SCHEDULES --------------- The ROUTEGEN.CTL you use will also build files for Schedule-R (Australian National Mail hour) and Schedule-T (International mail hour) for your convenience. You may wish to edit these depending on your mail traffic requirements for file attaches etc. HELP! ----- If you don't understand this document (please read it a few times first to make sure exactly what it is you don't understand) you should contact the network co-ordinator for your new network. The new network co-ordinators are : 620 - Brian Gatenby (02) 922-xxxx 626 - Alan Salmon (062) 58-xxxx 630 - John Blackett-Smith (03) 818-xxxx 690 - Leonard Holling (09) 339-xxxx If your network co-ordinator can't help you to understand it you can ring REALTORS (02) 387 5335 or SOFTWARE_TOOLS (02) 449-2618 Fidonews Page 11 29 Dec 1986 to leave a message and login again the next morning and collect your reply. If all else fails (and we really mean this to be an absolute last resort, only) ring either Gary Stern (02) 398-xxxx or Bill Bolton (02) 449-xxxx at home. Please DO NOT EVER publish these numbers to your users. We can't guarantee to be home but during the runup period to the introduction to the new network structure we will definitely try to be after 19:00 AEST. Just make sure you have contacted your network co-ordinator first. SPECIAL NOTES FOR FIDO + SEADOG USERS ------------------------------------- Setting up for SEAdog is a lot easier than for Fido! In Fido just set an external event starting at the time of your first mail event, not 5 minutes before. If you have set your pre-mail external event to occur 5 minutes before the mail event as we suggested, this will bring your Fido and SEAdog together as far as the no answer period just prior to an event. SEAdog has a 5 minutes no answer period while Fido has a 10 minute one. This external event, which should have the same exit errorlevel as your " /e" on your FIDOEXEC line. The length of this event should run till the end of normal morning mail time plus 1 minute. You still have to setup the net/node numbers in Fido with the sysop 4 command and adjust your XLATLIST.CTL file plus your ROUTEGEN.CTL file. You will need to change the node numbers in your CONFIG.DOG file. Take special note in the XLATLIST.CTL file as there are some special instructions for SEAdog users in it! Should you have any problems send a CRASH mail message to REALTORS (02) 387-5335 but only if you if you have SEAdog up and running on your board so that you can receive the CRASH reply!! (otherwise you just wont get a reply). December 1st, 1986 Gary Stern, Realtors, 155/215 [620/301] Bill Bolton, Software Tools, 155/219 [620/403] ----------------------------------------------------------------- Fidonews Page 12 29 Dec 1986 A new Echo Conference devoted to discussion of various subjects effecting Software Engineers and MIS professionals has been started by SuperResume Fido in San Francisco, 125/612, 415-546-0119. SuperResume is operated by Lee Johnson, the owner of LEE JOHNSON INTERNATIONAL, a recruiting firm specializing in Software Engineering and MIS Professionals since 1974. This 12 years of experience seeing candidates succeed and fail in their professional careers has provided some very interesting incites. What is needed is a national forum to discuss these issues and bring together new ideas from a wide variety of professionals. The proposed Echo Conference discussion areas are: 1. CARPLAN ........ Career Planning 2. COMP ........... Compensation Negotiation 3. CONTRACT ....... Contracting Pro & Con 4. COSTS .......... Cost-of-Living Comparisons 5. COUNTER ........ Counter Offer Experiences 6. GEOIND ......... Geographical/Job Market Activity 7. INTV ........... Interview Techniques/Experiences 8. JOMISA ......... JOBS: MIS - Applications 9. JOMISI ......... JOBS: MIS - Internals 10. JOMISN ......... JOBS: MIS - Network/Comm. 11. JOSEA .......... JOBS: Software Engineering - Applications 12. JOSEI .......... JOBS: Software Engineering - Internals 13. JOSEN .......... JOBS: Software Engineering - Network/Comm. 14. RESCOMP ........ Resume Composition Ideas 15. MISC ........... Software Careers Miscellaneous Subjects The file CARECHO.ARC is available for download on the SuperResume (tm) Fido (125/625 - 415-546-0119) for those who would like to participate in all or some of the above AREAS. It contains and ARC'd BACKUP.COM of all the subdirectories and dir.bbs's to make installation easy. In addition to coordinating the SOFTWARE CAREERS ECHO CONFERENCE, Lee Johnson is also making available his copyrighted SuperResume (tm) QUESTIONNAIRE.BBS file for Fido Sysops who wish to run it as the questionnaire feature of their Boards. It produces a detailed, accomplishment-oriented resume. This is extremely important because a resume is the single most important representation of a professional's career. Many well qualified candidates never even get to first base (the interview) because they were screened-out due to an inadequate resume. Nevertheless, most of people only think about their resume when they are considering changing jobs. As a result, many deficient, flawed, and poorly constructed resumes are in circulation today, and many people's growth is being held back. Lee Johnson is also offering Fido Sysops A WAY TO DEFRAY A PORTION OF THE EXPENSE OF OPERATING THEIR BOARDS. If a Board runs the SuperResume Questionnaire and obtains a completed SuperResume (or any resume) of a Software Engineering or MIS Professional candidate, Lee Johnson will pay a $500.00 US finder's fee to the Sysop and $50.00 US to the National FidoNet Fidonews Page 13 29 Dec 1986 Administrator if LJI successfully places that candidate. If the Sysop personally interviews the candidate, and provides a written appraisal of the candidate, the finder's fee goes up to ten percent (10%) of LJI's gross fee, which sometimes can be $15,000, or a $1,500 finder's fee. Detailed interviewing forms will be supplied if requested. If you are interested in either participating in the SOFTWARE CAREERS ECHO CONFERENCE, or in running the SuperResume (tm) Questionnaire (or both!), please contact Lee Johnson at: FidoMail 125/612; voiceline: 415-788-6000; dataline: 414-546-0119. ----------------------------------------------------------------- Fidonews Page 14 29 Dec 1986 Bill Hliwa, Sysop The Med Tech FIDO (260/0, 260/10) Western New York Net is formed ============================== Effective with NODELIST.353, the FIDO's of Western New York will be part of a new network: NET 260. The systems comprising NET 260 are located in the Greater Buffalo and Greater Rochester areas. Most members were originally in NET 107; others were independents in REGION 13. This reorganization will provide our area with more coherent communications by directly linking local NET 107 members (who previously had to deal with New York City -- 400 miles away) and the local independents. As an added benefit, NY MetroNet (NET 107) should feel some relief from their currently heavy netmail traffic. If you send Net Mail (EchoMail) to any of the affected nodes, please make a note of the change. For reference, the following nodes are shown with former and current node designations: Name Old Net/Node New Net/Node ------------ ------------ -------------- --Buffalo area-- The Med Tech FIDO 13/15 260/10(0) The IBM Temple 107/701 260/101 I-Tech1 107/703 260/110 AEOLUS 107/713 260/111 GATEKEEPER 107/733 260/112 The Public Domain 13/17 260/120 --Rochester area-- Modem Madness BBS 107/704 260/204 Infancy Research 107/708 260/208 Finger Lakes FIDO 107/716(700) 260/216(200) Hitch Hikers Guide 107/723 260/223 ----------------------------------------------------------------- Fidonews Page 15 29 Dec 1986 ================================================================= COLUMNS ================================================================= What is Baud? Anyone reading technical echomail may have noticed a large number of messages about baud rates, bit rates, band widths, and modulation techniques involved with modems. There is a fair amount of confusion relating to baud rate verses bit rate and how they are limited by the telephone line band width. This is nothing new, texts on the subject generally avoid the term "baud" except within the narrow context where it is germane. This article will define some of the various terms used in data communications, and discuss limitations of phone lines to communication speed. Serial transmission of data is the most common method of moving data over distance, and the most common way of interfacing serial devices to each other is RS232. The essence of RS232 is signal levels which represent ON or SPACE levels, and OFF or MARK levels. ON is any voltage between +3 volts and +15 volts while OFF is -3 to -15 volts. The signal shape is really a square wave centered at zero volts and is a baseband signal. A baseband signal is one whose spectrum extends down to zero hertz, or near zero. The signal is polled at regular intervals to determine its voltage, and therefore the data it contains. RS232 has only the two voltage levels defined so it is a binary coded signal. Besides signal shape and levels, RS232 defines a number of parallel signals such as "clear to send" and "data terminal ready". Some of these signals are status flags such as "carrier detect", while others are meant as flow control, such as "data terminal ready" or "request to send". Since a typical modem provides only the transmit and receive functions, the flow control must be done within the data stream. Some modems however send data as packets with error control (akin to XMODEM) that can recreate all of the hardware signals so as to make a distant terminal appear to be hard wired. Regular phone lines were designed for voice communications, but due to their wide use and therefore low cost, they have been widely used for data communications. A baseband signal such as is found in RS232 doesn't lend itself to phone lines since they don't have frequency response down to D.C. or zero hertz. When voice grade phone lines were designed the band of frequencies they had to pass was determined by the nature of human speech. Very low frequencies (below 300 hz) and higher ones (above 3000hz) were found to be unnecessary for voice recognition at the receiving end, as a result the total "BAND WIDTH" available to a phone user is only around 2700 hz. BAND WIDTH when used to describe frequency response is the difference in hertz between the high and low, half power frequencies. In electrical systems, power dissipated across a load (or resistance) in terms of voltage is: V * V / R. Where "V" in this case will be the amplitude of the sign wave being applied to the circuit. In between the high and low half power frequencies there will be a Fidonews Page 16 29 Dec 1986 frequency where the amplitude of the response wave will be maximized, call that voltage Vm. The half power points will be reached when V=Vm/sqrt(2). The output power at that point would be Vm * Vm / (2 * R) which is one half the mid band power. The cause for the fall off of power at different frequencies is due to capacitive and/or inductive elements in the circuit. In phone lines capacitance comes naturally in parallel, that is it tend to shunt the signal to ground. In this configuration the higher the frequency the lower the "resistance" will be. Inductance is added on purpose by the phone companies in the form of loading coils which are added to decrease signal attenuation in the mid frequencies. In any case the band width of a voice grade line is strictly limited so that many calls can be stacked on top of each other, in order to use transmission lines more effectively. Data equipment must strive to make the best use of this narrow band width. There is a hard limit to the amount of data that can be sent through a telephone line as will be seen later. The signal type of choice to carry data through phone lines is the sine wave. A sine wave has but one frequency associated with it. This means that if its frequency is within th band width of the line carrying it, then the received sine wave will not have its shape altered due to clipping of the high frequency components. This can't be said for the square or triangular waves which requires an infinite band width to fully describe them. The sine wave is simply defined: v= A * sin( w*t + p) A is the amplitude (in units of volts for this exercise) w is the frequency which must be in radians per second t is time in seconds p is the phase angle in radians Information can be encoded by the sine wave in three different ways. By altering "A" which is amplitude modulation (AM), by altering "w" which is frequency modulation (FM), or by altering "p" which is phase modulation (PM). There are mixed modes which come into use in the more exotic modem schemes, used to get the really high bit rates. FSK or frequency shift keying was the most widely used method for data transfer through modems. This is a FM process whereby a RS232 MARK would be represented by the presence of one frequency while a SPACE would be indicated by another frequency. Now is the time to introduce the term BAUD. A "BAUD" is the time interval in which data is carried, that is the minimum time in which a signal holds a single state which the receiver is to recognize and convert into data. The baud rate is how many BAUD times occur in a second. The baud rate is NOT the same as the bit rate as will be seen later in multiple state modulation. In FSK type modems (Bell 103) the baud time happens to be the same as the bit rate since each signal state encodes a single bit. Many would think that the baud rate is limited to highest frequency available to be transmitted (3000 hz) but this is not necessarily so. Nyquist showed in 1928 that the maximum signal change rate (baud rate) for a band width "W" would be 2*W baud. This is Fidonews Page 17 29 Dec 1986 called the Nyquist rate and is an upper limit that assumes no inter-symbol interference. This could be visualized by considering a sine wave. Each cycle has a positive and negative part. The amplitude in each part could be independently altered while still having a sine wave, therefore a 1200 hz signal could be changed 2400 times a second which is 2400 baud. This type of change (AM) is not very useful in phone lines since it is the type of change most commonly caused by natural phenomena. In Bell 103 the baud rate is commonly 300 which is over 3.5 cycles at the lowest carrier frequency. The practical considerations of detecting frequency changes requires about 1.5 cycles so 300 baud is some what conservative. PSK or phase shift keying gets by the frequency barrier that keeps FSK from producing the higher bit rates. In PSK (a PM method) the only parameter in the sine wave changed each BAUD is the phase angle "p". The Bell 212A modem specification uses a four level phase modulation technique. The term four level means that four different phases are used and detected by the receiver during each BAUD. The number of bits an M level state can represent is n=log2(M) or log(M)/log(2). A four level state can represent two bits during each baud. In the 212A specification +90 degrees would be 00, 0 degrees 01, +270 degrees 11, and +180 degrees 10. The 212A baud rate is 600 which means the bit rate would be: bit rate=600 BAUD/second * 2 bits/BAUD= 1200 bits/second To increase the bit rate to the next state would require 3 bits/baud or 8 phases. To get 2400 bps using such a scheme would require 16 different phases (22.5 degrees apart). The problem here is that one class of noise present in phone lines called "phase jitter" can cause phase errors up to and sometimes over 30 degrees. To avoid the bulk of this type of noise the phase angle difference should be kept above this amount. The 2400 baud modems common today use a form of QAM (quadrature amplitude modulated). This method uses a combination of two waves with different amplitudes to get the required 16 levels. A QAM signal can be expressed in equation as follows: s(t)=a(t)cos(wt+p)+b(t)cos(wt+90+p) a(t) is the in-phase modulating wave form while b(t) is the quadrature modulating wave form. During each baud a(t) and b(t) are constants so the equation simplifies to: s(tn)=c*cos(wt+theta+p) {p is a single arbitrary phase angle tn stands for a specific baud time c=sqrt(a*a+b*b) theta=atan(b/a)} The new pure sine (cosine) wave has amplitude and phase differences which can multiply the number of states possible. If there are 4 values for amplitude and 8 values for phase then the signal could have 32 different states or five bits. The random variations in phase "p" has less effect the outcome since it effects both waves the same. The phase difference in the Fidonews Page 18 29 Dec 1986 resultant wave is due to the interaction of the two wave forms. QAM is the method used to get up to 9600 baud out of a phone line. Other types of noise are present in a phone system, and are mostly due to switching and cross over with other wires. The error rate at the higher bit rates would be unacceptable if there weren't some error recovery used. This is now quite easy to do from a hardware standpoint, since the memory and processing power needed to do it takes a small amount of space and cost little enough to make the increase in bit rate worth it. The ability for high speed modems to run will increase due to another reason. More and more fiber optic phone line will replace conventional ones. These are immune from many of the noise sources that effect copper wires, sources such as RF and magnetic fields. The ultimate bit rate that could be "pumped" through a phone line is fixed by the band width AND the signal to noise ratio. Shannon's law relates random bit transmissions/second to band width and signal to noise ratio. It is derived from the concept of entropy. Entropy is a measure of randomness in a system. It is really a thermodynamic property but has applications in information theory. The maximum bit rate for a channel with signal power S and noise power N is given by: C=BW log2(1+S/N) where BW is the band width, S is the signal power and N is the noise power. With a typical band width 2600 hz and a typical signal to noise ratio of 30db (or 1000/1) the bit rate would be: bit rate=2600 * log2( 1001 ) or 25,914bps The noise factor is assumed white or Gaussian. This kind of noise is unavoidable in electrical systems. In fact "N" can be calculated by: N=kTW where k=1.37e-23 joule/degree T is absolute temperature (Kelvin) W is the band width in HZ This product gives "N" in terms of joules per second or watts. At room temperatures noise would be on the order of 1e-17 watts over a 2600 hz band width. If a phone signal were just 0.1 watts the signal to noise ratio could be as high as 160db. In practice it is about 30db so it can be expected that the signal to noise ratio will increase in the future so that the top bit rates will increase, and this increase will happen without an increase of the band width available. One last problem to consider with the high speed modems is compatibility. To get 9600 bps from a 600 baud signal would require 65,536 levels in a state. There is no obvious way in which to assign a level to a 16 bit pattern so the manufacturer must invent an "ALPHABET" for that conversion. Until an alphabet is standardized as well as error recovery techniques there is simply no way the modems will talk to each other. Fidonews Page 19 29 Dec 1986 GLOSSARY: Alphabet: A table to convert signal states into characters they represent Amplitude modulation: Where information is encoded by changes in amplitude only. Band width: Range of frequencies within the half power limits. That is the difference between the two -3db frequencies. Baseband: The signal at its original frequency and shape. Baud: The minimum time where all signal parameters are held constant. Baud rate: The number of times the basic signal can be changed per second. Bit rate: The number if bits per second passing through a channel. In a modem it is the baud rate times the number if bits per baud. Decibel (db): 10 * log10(p2/p1) where p2 is referenced to p1. Both p1 and p2 represents power. For voltage db is calculated 20 * log10(v2/v1) Frequency modulation: Where information is encoded by changes in the carriers frequency. FSK: A way of represents data by a discrete change in frequency of the carrier. Hertz: Number of events per second. Modulation: The process of varying a signal according some aspect of another signal. Phase: The angular displacement of a cyclic signal In a sine wave Y=A sin(wt+p) p is the phase. Phase modulation: Technique of changing phase of signal to represent changes of the baseband signal. References: 1.*Clark, A.P., 'Principles if Digital Data Transmission' 2nd ed. (1983) 2. Martin, James, 'Telecommunications and the Computer', (1979) 3. 'IBM PC Technical Reference', (July 1982) 4. 'Hayes Smartmodem 1200 manual' *Reference (1) gives the most technical detail and over 500 other specific references. ----------------------------------------------------------------- Fidonews Page 20 29 Dec 1986 ================================================================= WANTED ================================================================= David Kohen, 164/7 Writer wanted Hi! I'm the Technical Editor for a new Hong Kong based magazine,and I'm looking for someone, or someones, to write a regular column on the North American computer scene. What we're looking for is something a lot like Jerry Pournelle's Chaos Manor in Byte (you can take that as a compliment, Jerry, if you come across this), with coverage of events, conferences, new products, etc. Since we can't, yet, offer Byte's kind of money or expenses, we really need someone who is working in the field, gets around, can write and wants to earn some extra money. Most of the time you'll decide for yourself what you want to cover. Occasionally we'll ask you to do something specific. We're also open to receiving articles on a one-off basis, including reviews, programs etc. We'll pay on a sliding scale, according to how much editing is needed, for text, photos and programs. All submissions should be supplied on IBM compatible disk. In the case of programs they should be heavily annotated, and public domain (they'll all be posted on SEAnet, our local Fido host). IBM, Mac and Unix-based programs are more likely to get into print, the Amiga and Atari STs are not available here. Obviously Mac programs should be on a Mac disk (although we'd still prefer the text in IBM format if possible, we don't yet have an in-house Mac). If you are interested, or you know someone else who is, I can be reached by mail at: Interface Magazine 1911, C.C. Wu Building, 302 Hennessy Road, Wanchai, Hong Kong. Or (preferably) through Fidonet on 164/7 ----------------------------------------------------------------- Fidonews Page 21 29 Dec 1986 ================================================================= FOR SALE ================================================================= MAGAZINE ON DISK FOR IBM PC AND COMPATIBLES The first issue of BIG BLUE DISK, a magazine on disk for the IBM Personal Computer and compatibles, will hit the stands this October. It is contained entirely on a floppy disk. Each issue contains programs, articles, feedback from subscribers, program reviews and demos, and more. For example, issue number one contains the following: - PLANET OF THE ROBOTS: In this text adventure, a time warp has transported you to a future Earth where robots rule. Can you find your way back? - HOP-A-LONG HANGMAN: A new version of the classic word game, with three different skill levels and word sets. - LIFETIME CALENDAR: Travel back in time or plan the future. Display any month from January, 1753 to December, 4999. - LOAN AMORTIZATION: Calculate simple interest loan terms that best suit your budget. This easy-to-use program produces a full amortization schedule. - STRING ART: This program generates many captivating patterns. Check it out; a little high-tech cloud watching is good for the soul. In addition, BIG BLUE DISK #1 contains a column of hints and tips; and a report of late-breaking news in the computer industry. Also, for the first time anywhere, BIG BLUE DISK presents a review of VersaForm XL version 4.0, the latest version of an inexpensive but powerful, programmable, forms-oriented database. This issue will be available at many outlets nationwide, including Waldenbooks and B. Dalton Booksellers. You can also order it by direct mail by sending $9.95 (check, money order, or Visa/Mastercard/American Express accepted) to: BIG BLUE DISK, PO BOX 30008, SHREVEPORT, LA 71130-0008. Mail subscriptions are also available: One year (12 monthly issues) costs only $69.95. (A 41% savings over newsstand price.) A six-month subscription is available for $39.95. BIG BLUE DISK requires an IBM PC or compatible, with at least 256K of memory and a Color Graphics Adapter or compatible graphics board. Send questions/comments to Daniel Tobias on FIDO 19/216. ----------------------------------------------------------------- Fidonews Page 22 29 Dec 1986 W.R.Hunter, 109/626 Disk I/O Slowing you down? Are you dealing with a large Database that takes forever to read? Is your Network bogged down due to disk seek time? Do you simply want to make BETTER use of the EXTENDED OR EXPANDED memory capacity on your system? Your solution is: D I S C A C H E V 0.01 DISCACHE can help you recover lost seconds when it counts! DISCACHE works by keeping commonly accessed disk data in memory so that when such data is read it is copied from memory rather than read from disk. DISCACHE supports 3-types of memory: 1. CONVENTIONAL (to 640K) 2. EXTENDED - AT memory via BIOS INT 15 3. EXPANDED - via Lotus/Intel EMS DISCACHE can help you utilize ALL of your Extended/Expanded memory to the fullest, as it helps you get the most from your system. DISCACHE is available NOW, not for the full price of $99.00, but for a LIMITED TIME at $49.00 (Through Dec 31st, 1986) HOW DO I GET DISCACHE? Simply write to: WEG Systems, P.O. Box 5072, Springfield, VA 22150. HOW DO I GET MORE INFORMATION? There are 2-ways to obtain more information: Write to us at the address above -OR- Call us via MODEM (with your computer) to our support line at (703)-425-0695, WAFRUG_BBS, (1200/300 baud) 24hrs daily, 7-days weekly. ----------------------------------------------------------------- Fidonews Page 23 29 Dec 1986 Now available from MidWest MIDI Consultants,Inc. Systems Design Associates' PROMIDI(tm) Studio System SDA-200. The SDA-200 Promidi Studio System consists of the Midicard and associated software for an IBM Personal Computer or Compatible. PROMIDI RECORDS MIDI MUSIC DIRECTLY TO DISK IN REAL TIME: Recording length and number of recordings/tracks limited only by disk space. Real-time recordings of 60,000 notes with a 2-drive system, 1.5 million with a 10Meg hard disk, with only 256K of RAM in the host computer. PROMIDI'S ONLY LIMIT ON STORAGE IS DISK SPACE. PROMIDI LETS YOU RECORD IN FILES, RATHER THAN TRACKS: Promidi FILES EACH SUPPORT ALL 16 MIDI CHANNELS. You can edit, extract or copy individual MIDI channels in a file, even move MIDI music from one channel to another. Further, with the new Midimerge, Promidi users can record up to EIGHT MIDI INSTRUMENTS IN A FILE AT ONCE WITH NO LOSS OF FIDELITY yet edit them individually, just as if they had been recorded one-at-a-time. PROMIDI'S RESOLUTION IS 192 CLOCKS PER BEAT AT ALL TEMPOS: PROMIDI SOFTWARE IS DOWNLOADABLE: All operating instructions for the Midicard interface are part of the Studio System recording software. The absence of PROM chips on the interface ELIMINATES chip-changing,and incompatibility caused by MULTIPLE HARDWARE VERSIONS. PROMIDI GIVES YOU MORE POWERFUL EDITING TOOLS: Automated Punchin/Out, Cut & Paste, MaxAuto quantizing, Scalewise & Intervalic Tramsposition, Slide, Chaining, StepEdit/Entry and more. Promidi lets you PUNCH IN VOICE CHANGES on any beat. BUILT-IN FSK TAPE SYNC and METRONOME, plus a ONE-YEAR WARRANTY on both hardware and software. And more products compatible with Promidi are in the works. MidWest MIDI and SDA offer a 30 day money back gaurantee to all mailorder customers, if not completely satisfied with the PROMIDI System. Try before you buy DEMO program disk are also available. More information about PROMIDI and the other brand name MIDI products for the Commodore AMIGA,64/128, ATARI ST, APPLE //,& MAC is available online on MidWest MIDI BBS (405) 733-3102 - 147/6 -. MidWest MIDI BBS - FIDO 147/6 - 1200bps - 24hrs. BBS #: (405) 733-3102 ----------------------------------------------------------------- Fidonews Page 24 29 Dec 1986 ================================================================= NOTICES ================================================================= The Interrupt Stack 17 Jan 1987 Deadline for voting on the proposed bylaws. Your ballot MUST be received by this date! 17 May 1987 Metro-Fire Fido's Second Birthday BlowOut and Floppy Disk Throwing Tournament! All Fido Sysops and Families Invited! Contact Christopher Baker at 135/14 for more information. 24 Aug 1989 Voyager 2 passes Neptune. If you have something which you would like to see on this calendar, please send a message to FidoNet node 1/1. ----------------------------------------------------------------- The LAPTOP echomail conference deals with the TRS-80 Model 100, 102, 200, and other such laptop computers (but not the IBM PC portables). If you are interested in joining this conference, please contact the nearest of Fido 138/14, Fido 115/100, or Fido 11/301. ----------------------------------------------------------------- Marsha Hague, 14/61 We are looking for anyone who has purchased a Whisper Reader portable data terminal being liquidated by MPC Sales, or who may own an original LEX-31, both manufactured by Lexicon. Whisper Line is a BBS set up for owners of these terminals to exchange tips and techniques. Give us a call! Whisper Line, 24 Hours/300 bps, (507) 289-8211 ----------------------------------------------------------------- Fidonews Page 25 29 Dec 1986 *Official IFNA By-laws Ballot Official IFNA Articles of Association and By-laws Ballot We, the interim directors of IFNA, submit for ratification the Articles of Association and By-laws as published in FidoNews number 349. In accordance with the recommendation of the By-laws Committee, each person listed as the Sysop of one or more FidoNet nodes, as of NODELIST.311 dated November 7, 1986, is entitled to ONE vote. The proposed IFNA Articles of Association and By-laws, as published in Fido349.NWS dated December 22, 1986, should be: (Check one line) Adopted ________ Rejected ________ I am the SYSOP of record a FidoNet node which was listed in NODELIST.311 dated November 7, 1986 and have the right to cast one vote. There will be ONLY be one vote per person. There will be ONLY one vote per net/node number. I understand these rules and cast my ballot in accordance with them. _______________________ ___________ Signature Date _____/______ Net Node Return this ballot via U. S. Mail to arrive not later than January 17, 1987 at: IFNA Ratification C/O Christopher L. Bonfanti, CPA Aselage, Kiefer & Co. 701 Emerson Road, Suite 201 Creve Coeur Corporate Center St Louis, Mo. 63141-6709 Aselage, Kiefer & Co. are Certified Public Accountants and will provide an independent count of the vote and publish the results in FidoNews. Votes received by Saturday, January 17th will be included in the results. -----------------------------------------------------------------