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              LET'S TALK!
         Computer to Computer
                  by 
             Jack MacKenn
 
 Many of us that have modems on our 
 Adams feel that computer to computer 
 communication is relatively easy.  
 After an uncertain start, we read an 
 easy-to-follow article such as Ralph 
 Mason's in the last issue, fire up 
 our MEX (or IMP, Madam7, or even 
 AdamLINK), call our local friendly 
 BBS and have a nice session.  We read 
 messages, post messages, and even 
 upload & download files from time to 
 time.  After a few sessions, we have 
 the procedures down pat and wonder 
 why we were hesitant about getting 
 started.  After all, there's nothing 
 to this!
 
 That's the way I felt.  Then one day 
 at work, it became evident that we 
 would start transferring files elec-
 tronically between our offices in 
 Dahlgren, Va. & White Oak, Md.  No 
 sweat....or was it?  It occurred to 
 me that all of my computer to comput-
 er communications had been done with 
 a bulletin board, i.e., a computer 
 with special software set up to 
 answer and service incoming calls.  
 That's not the same as calling "just" 
 another computer nor the same as 
 having another computer call you.  It 
 was apparent that I needed to do some 
 studying.
 
 I use an MS-DOS version of MEX at 
 work, so it seemed that learning to 
 talk computer-to-computer could be 
 accomplished on my Adam.  I posted a 
 message on our BBS requesting assist-
 ance.  No one responded with any 
 helpful ideas but Gene Manning volun-
 teered to help out and learn along 
 with me.  We set up a schedule for a 
 Sunday afternoon attempt (lowest 
 phone rates).  Gene was using the 
 internal Adam modem while I was up on 
 my external Avatek 2400.  We both 
 started using MEX.  It didn't work.  
 We couldn't get our modems to talk to 
 each other.  We tried several differ-
 ent combinations but failed each 
 time.  In retrospect, the biggest 
 problem was getting one modem to 



 answer the other.  I believe AdamLINK 
 has a Smartkey labeled ANSWER but I 
 was determined to use MEX (I don't 
 have an MS-DOS version of AdamLINK, 
 you see).  After many tries and 
 learning a lot of things NOT to do, 
 Gene and I decided that we had en-
 riched the phone company enough for 
 one afternoon and called a halt.
 
 My problem still existed...how to 
 transfer files electronically.  The 
 folks at the White Oak were modem 
 transfer novices also.  They knew a 
 little and, after the session with 
 Gene, I felt a knew a little.  We 
 decided it was time to try.  One 
 factor in our favor was that we were 
 using identical Hayes-compatible 2400 
 bps modems.  We decided they would 
 initiate the call.  My modem would 
 answer.  After the session with Gene, 
 I read the instruction book that came 
 with my Avatek (now there's a radical 
 idea..read the manual!) and discov-
 ered there were at least two ways to 
 set up your modem to automatically 
 answer an incoming call.  The first 
 is to set one of DIP switches.  The 
 second is to set the S0 register to 
 answer after n number of rings.  I 
 don't like flipping DIP switches so 
 setting the register was the way for 
 me.  Changing the S0 register (or any 
 other register) is fairly easy.  With 
 your Hayes-compatible modem on and 
 your communications program in the 
 terminal mode, issue the command 
 ATS0=2 <cr>.  This tells the modem to 
 answer after the second ring.  The 
 response on your screen should be 
 "OK".  If your modem has an AA 
 (auto-answer) light, this light 
 should now be on.  Your modem will 
 now answer every incoming call after 
 the second ring and issue a loud 
 burst of computer stuff that will be 
 recognized by the calling modem.  
 [Note that EVERY call will be an-
 swered by your modem now, even a 
 normal call from, say, your 
 mother-in-law who would receive a 
 rather rude blast in her ear from 
 your modem.  I have often considered 
 setting this up during the dinner 
 hour to handle telephone solicitors.] 
 After setting my modem in the AA 
 mode, the call came and a connection 



 was made.  (By the way, the folks at 
 White Oak were using PROCOMM).  I 
 typed in HELLO...wait a minute!!  How 
 come I don't see it??  They type 
 HELLO back, I see that.  Interesting, 
 we read each other but not ourselves.  
 Turns out we're both in the terminal 
 mode with no echo.  This is discon-
 certing, I like to see what I'm 
 typing.  The options are two; both 
 parties must be in the terminal mode 
 with local echo (the L command in 
 MEX) or one party must be in the full 
 duplex mode (the E command in MEX) 
 while the other is in the terminal 
 mode.  We decide that I will go into 
 the E mode.  This is easy, get back 
 to the command mode (ESC E) and then 
 enter E<cr>.  This will put you in 
 the terminal mode with full echo.  I 
 did it and it worked fine.  Turns out 
 that was the hard part.  Once we got 
 to that point, uploading and down-
 loading were easy...practically the 
 same as working with our BBS.  If I 
 was sending them a file, I would go 
 to command mode (ESC E), type S file-
 name<cr> and wait for them to start 
 receiving.  If I was receiving a 
 file, I would go to command mode, 
 type R filename<cr> and wait for the 
 file to come.  The one big difference 
 I noticed when receiving is that I 
 did not know how big the file was 
 until the transfer was complete.  At 
 the end of the transfer, I returned 
 to the terminal mode (with full echo) 
 to confirm that the transfer looked 
 good at both ends.
 
 Since that time, several files in 
 excess of 100k have been transfered 
 both ways without difficulty.  One 
 other thing we learned was that it 
 was much more efficient to crunch the 
 files before transmission to save on 
 long distance charges.  We use an 
 archiving program very similar to the 
 public domain CPM archiving programs 
 available to us in the Adam world.
 
 All this leads to a fairly simple set 
 of instructions for talking 
 computer-to-computer.  First, both 
 modems should be set to the same 
 speed.  This is easy; for example if 
 a 1200 bps modem is calling a 2400 
 bps modem, the 2400 modem should be 



 driven by MEX12 instead of MEX24.  
 Second, the receiving modem needs to 
 be set for Auto-answer.  Third, it 
 should be determined who is going to 
 provide the echo.  I recommend the 
 receiving end provide the echo.  
 There is a small problem here.  My 
 MEX does funny things if I go into 
 the terminal mode with full echo if a 
 connection has not been established.  
 I get around that by establishing the 
 connection in the terminal mode then 
 switching to full echo mode (ESC E 
 then E<cr>).  At this point, you can 
 chat and transfer files to your 
 heart's content.  At the end of the 
 session, your modem can be reset to 
 the non-answer mode by entering 
 ATS0=0<cr> from the terminal mode.  
 Turning the modem off will accomplish 
 the same thing.  NOTE:  changing the 
 register setting of your modem will 
 only last for that session, i.e., 
 until you turn your modem off.  If 
 you want to make the register changes 
 permanent, the changes need to be 
 written to the modem's non-volatile 
 memory by adding &W to the register 
 change command.  For example, enter-
 ing the command ATS0=2&W will cause 
 your modem to be in the auto-answer 
 mode (2 rings) every time you turn 
 the modem on.  It will remain that 
 way until it's changed back by the 
 command ATS0=0&W.
 
 During the time I was learning the 
 above, Gene was busy trying to figure 
 it out.  He was able to establish an 
 Adam to Adam link with Les Wilsey.  
 Gene called me one Friday evening and 
 we finally established our own Adam 
 to Adam link at 1200 bps.  We chatted 
 and successfully transferred a file 
 each way.  I learned a lot from this 
 entire exercise that helped me at 
 work as well as allowing me to make 
 better use of my Adam.  It was an 
 excellent example of our club members 
 helping each other to learn.
 
 The procedures written above are 
 certainly not the only way to commu-
 nicate computer-to-computer.  They 
 may not even be the best way, but 
 they worked for me and they should 
 work for you.
 



                                                                         
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