Shelezyak Planet - RS-232 interface diagram.

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             RS-232 INTERFACE FOR SPECTRUM COMPUTERS
             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(c) KOHASOFT'1991
(c) UAЗPRQ'1992
                         продолжение

            █8┌───┬───┬─────┐11
      D0'   █────┤DO │ PT│GATEO├────┐
            █   7│   │   │     │14  │
      D1'   █────┤D1 │   │GATE1├────o──>+5V
            █   6│   │   │     │16  │
      D2'   █────┤D2 │   │GATE2├────┘
            █   5│   │   │     │              KPS8OВИ5ЗА
      D3'   █────┤D3 │   ├─────┤
            █   4│   │   │     │13
      D4'   █────┤D4 │   │ OUTO├─────────┐
            █   3│   │   │     │17       │
      D5'   █────┤D5 │   │ OUT1├──       │
            █   2│   │   │     │10       │
      D6'   █────┤D6 │   │ OUT2├──       │
            █   1│   │   │     │         │
      D7'   █────┤D7 │   ├─────┤9        │
            █  19├───┤   │ CLKO├──────┐  │
      A5    █────┤A0 │   │     │15    │  │
            █  20│   │   │ CLK1├──────o  │
      A6    █────┤A1 │   │     │18    │  │
      ────  █  21├───┤   │ CLK2├──────o  │
      CS-53 █────┤CS │   ├─────┤      │  │
      ──    █  23│ ─ │   │     │24    │  │
      WR'   █────┤WR │   │ +Ucc├──>+5V│  │
      ──    █  22│ ─ │   │     │12    │  │
      RD'   █────┤RD │   │  GND├───┐  │  │
            █    └───┴───┴─────┘  ─┴─ │  │
      CLK-2 █─────────────────────────o  │
    2.0 mHz █  27┌───┬───┬────┐20     │  │
      D0'   █────┤D0 │PCI│ CLK├───────┘  │
            █  28│   │   │  ─ │9         │
      D1'   █────┤D1 │   │ TxC├──────────o    KPS8OBB51А
            █   1││ │ ─ │25 │
      D2' █────┤D2 │ │ RxC├──────────┘ 3┌──┐2
            █ 2│ │ ├────┤19 ┌───────┤ >├────>>TxD
      D3' █────┤D3 │ │ TxD├─────┘ 5├──┤4
            █ 5│ │ │ ─ │24 ┌────┤ >├────>>DTR
      D4' █────┤D4 │ │ DTR├────────┘ 7├──┤6
            █ 6│ │ │ ─ │23 ┌───┤ >├────>>RTS
      D5' █────┤D5 │ │ RTS├─────────┘ └──┘
            █ 7│ │ ├────┤3 15┌──┐14 K561 PUČ
      D6' █────┤D6 │ │ RXD├───────┤ <├────────o─<+5V │-R3 █ █ █
            █ 12│ ─│ │ │4 │100k │ │ │
      A5 █────┤C/D│ │ GND├────┐ ┴ ┴ ┴
            █ └───┴───┴────┘ ─┴─ │
      RESET'█──────────────────────────┘

 Possible application of counters with variable coefficient
sharing instead of DPKD on KPS8OVI5Z. It is not obligatory in all cases
feed meander onTxC & RxC inputs of KPS8OBB51 controller;
It is also desirable to limit the clock frequency of LSIs to 2 MHz.
If there are any problems with the programming and operation of KPS8OVI5Z, you can
try to reduce the supply voltage on it to 4.5V (by
serial connection of a diode type KDS22 in the +5V circuit
'forward' direction).  When using a branded analogue m/skh
I8253 there is no need to do such modification.  Should
Please note that the connecting cable between the computer and RS-232
is a strong emitter of interference to receiving equipment
radio channel in data exchange systems - Packet Radio, RTTY,
AMTOR etc., therefore the cable length should be as short as possible
(no more than 0.5m).
  Interface pin assignment:
 TxD -"Transmit Data", information output of the transmission block. You-
 The TXD stroke is connected to the communication channel (modem input).
 DTR -"Data Terminal Ready", terminal readiness.  Active
 the level (low) of this signal informs external devices
       notification about the terminal’s readiness to receive information.
 RTS -"Request To Send", transfer request. The active level is
th signal terminalinquires about the possibility of transfer
       data to an external device.
 RxD -"Receive Data", information input of the receiving block.  On
 RXD input from the communication channel (modem output) code enters
       serial format.
 DSR -"Data Send Ready", transmitter readiness.  Active level
 The level of this signal indicates the readiness of the external device.
       swarms to exchange.
CTS -"Clear To Send", transmission resolution.  Active level
 of this signal, an external device (modem) indicates the
       readiness to accept data from the terminal.

 to be continued...

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