ZX-News #26 03 апреля 1997

Железо     Модем

Iron - Description of the XTR-modem.

            ----- ---- IRON

  Initially we planned to improve VICOMM and make it as cheap. 
Alas, no half-measures have failed, initial handicap VICOMMa 
not allowed to implement all ideas, namely: the ability to 
automatically (no buttons)-hook, call control and Employment 
line. All this provides unprecedented opportunities, such as: 
pulse and tone dialing, the ability to dial, caller ID, dialed 
the phone with a parallel, automatic detection Caller ID (CLI), 
as well as a modem better service and improving the quality of 
reception / transmission. 


  I do not do nothing to stop the incidental function of a 
modem - caller ID, because AON think certainly useful and 
necessary function in the modem. 


  Therefore software compatibility with VICOMMom was lost, but 
not completely. 


  When communicating on the network process is as follows: you 
turn on the machine, load a program, turn off the monitor, 
Switch the phone off to avoid ringing and go to bed. And in the 
morning over a cup of tea and a plate of semolina, you are 
flipping through ascended message. 


  Has an internal modem (it's cheaper
structure) - it is stuck in the slot SCORPION / KAY and his 
connection is not accompanied by heating of the soldering iron. 
Connecting to other SPECTRUM-compatible machines escort

the inclusion of a soldering iron and use thereof
according to instructions.


  The modem is galvanically isolated from
line (the breakdown voltage of 1.5 Kv). Decoupling is done by 
means of optocouplers, and not transformer, as in VICOMMe that 
it is yet again cheapens the design and reduces its dimensions.



  Met all the standards for terminal
device telephone network (maximum
drain 250 mA, maximum voltage -
220 V, maximum current - 100 mA).


  When the computer is off when the modem
do not enjoy, as well as by pressing RESET,
modem off line and does not
it no effect.


  The signal of the modem has a frequency
bandwidth to transfer more than 20 kHz, at the reception - more 
than 10 kHz, which is more than enough to share for 3200 baud 
(if the line and station will allow). Maximum tested

speed - 3900 baud, the results are encouraging.


  An important detail: the implemented hardware support 
exchange with a modem in the face gating process chosen by 
kvartsovannoy frequency signal WAIT. The idea of ​​this - the 
program was written under the clock speed of CPU SPECCY not 
lower than, say, 3.2 MHz, and all machines with greater 
frequency retarding to the desired. Unfortunately,

there is a limit - no more than 7.0 MHz (typical turbo mode).


  It is very convenient - the quality of communication does not 
depend on makeshift machines and do not use the turbo button, 
everything is working, including CONNECT SCORPION-PENTAGON.



  Possible to transmit an analogue signal in line with the 
quantization of the 16 levels by PWM modulation with sampling 
rates up to 23 kHz (voice capabilities AON RUSS-16 and above, 
as well as DIGITAL STUDIO). 


  Structurally the hardware components is a printed circuit 
board size 75 * 70 mm and contains a connector in the form of 
slots SCORPION / KAY and telephone line jack. Current 
consumption from the power source SPECCY about 100 mA.

+12 V is not required.


             ----- SOFT ----

  While the modem into production, we adapt
existing terminal program, as well
also write new ones. Already altered MODEM 3.6 and
written by Caller ID program.


  Peredelany MODEM 3.6 can be used for communication XTR-VICOMM.


  This project is supported and OMEGA GROUP
program Macro-Modem will be adapted
under the XTR.


  We are confident that XTR completely supplant
All VICOMMy and will become the standard platform ZX-SPECTRUM.


          ----- ---- WISHES

  We know that today, except for Peter and
Moscow, modems do not have nowhere in sight. A
therefore offer - try this product
and in your region, you will not regret it.


       ----- ---- PROGRAMMING

  For the curious, users report
minimum required information. Communicating with
The modem is the only port
address # B7 (183).


 IN A, (# B7), if the line is not busy modem

 Bit7 Bit0

  0 0 line is not connected to the modem

  0 1 Parallel off the hook. apparatus

  1 0 call (possible bugs)

  January 1st line is free



  IN A, (# B7), if the line is busy modem

 Bit7 always 0
 Bit0 through it are taken by data



  OUT (# B7), A

 Bit0 when the line is busy - passed

       data when receiving gb = 1

       With the release of the line is irrelevant
 Bit1 1-take line

       0-free line

 Bit4 bits determine the time until which
 Bit5 hardware stretch interval of time Bit7 Meni between two 
consecutive commands Bit6 DAMI IN A, (# B7) or OUT (# B7), A 

 Bit7-Bit4
 # 00 times .000002 * 16 seconds
 # 10 times .000002 * 15 seconds
 ...
 # E0 .000002 time * 1 sec
 # F0 asynchronous mode, NO WAIT


  For the case # F0 did not stretch
all done, as the port # FE in emulation mode VICOMM.


  What are bits of 7.4?


          example:


        LD A, #? 0 *

        OUT (# B7), A *

        IN A, (# B7)!

        POP AF

        IN A, (# B7)!

without hardware Support Click Here for instructions marked ", 
the period of performance is: 


                   ticks seconds


  PENTAGON 11 +10 = 21 .000006

  TURBO PENTAGON 11 +10 = 21 * .000004!

  SCORPION 12 +10 = 22 .0000063

  TURBO SCORPION 12 +10 = 22 * ​​.000004!

  KAY 12 +10 = 22 .0000063

  TURBO KAY 12 +12 = 24 .0000034


  * Plus WAIT

  ! priblizitelno


  For the case of XTR period for all machines
equalized, increasing (!) to the value set in bits, 7.4 (except 
for the values ​​# F0). 


  Same for sprvedlivo OUT (# B7), A and
any combination of IN / OUT to port # B7.

Primechanie_1: Naturally, the program should be to write under 
the worst car to the execution of commands on this machine was 
less than the specified time, to which everything is stretched 
(or else it will be compression!).


primechanie_2: period without stretching does not
must be less than .00000229 seconds, (8 bars
neTURBO PENTAGONa, 16 cycles TURBO PENTAGONa), or stretching 
will not occur. 


       Example of a pause in .002 seconds:

W002 XOR A

        OUT (# B7), A; period of 32 uS

        LD B, 62
W002_1 IN A, (# B7); =. 62 *. 000 032 001 984

        DJNZ W002_1

        ...


  On any machine it will be .002 seconds, regardless of the 
TURBO / neTURBO. 


        Programming Examples:


  free line OUT (# B7), # F0

  take a line OUT (# B7), # F3


   Dialing (WAIT ... in seconds):

ADRNUM DB "1234567"

DIAL OUT (# B7), # 00; reset line

        WAIT 0.5

        OUT (# B7), # 02, take the line

        LD HL, ADRNUM

        LD C, 7
DIAL7 WAIT 0.5

        LD A, (HL)

        SUB # 30

        JR NZ, DIAL7_0

        LD A, 10, for zero-ten
DIAL7_0 LD B, A

        INC HL

        PUSH HL

        PUSH BC

        CALL DIALN; set of numbers

        POP BC

        POP HL

        DEC C

        JR NZ, DIAL7

        WAIT 0.5

        OUT (# B7), # 03

        RET

DIALN OUT (# B7), # 00

        WAIT .06

        OUT (# B7), # 02

        WAIT .04

        DJNZ DIALN1

        RET


    Data Transfer (principle VICOMM):


        OUT (# B7), # F2

        WAIT

        OUT (# B7), # F3

        WAIT

        repeat the algorithm


             Call Waiting:

WTCALL LD DE, # 8180

        XOR A

        OUT (# B7), A
WTCL0 LD BC, # FF00
WTCL1 WAIT .002

        IN A, (# B7)

        AND D

        CP E

        JR NZ, WTCL2

        INC C
WTCL2 DJNZ WTCL1

        LD A, C

        CP 30; antiglyuk

        JR C, WTCL0; no phone call
WTCL3 LD B, 0; forward to the end
WTCL4 WAIT .002; call

        IN A, (# B7)

        AND D

        CP E

        JR Z, WTCL3

        DJNZ WTCL4
Or you can hold the line

        RET


  ! not recommended to hold the line at the time of the call 
(after all 120 volt !!!), have to wait for a pause between 
calls (this holds for any terminal device telephone line).



        __________________________