Terminal Emulation

Application

In terminal emulation mode, HUNTER can be used as:

  1. A remote terminal for dialup timeshare computer services.
  2. As a peripheral to other computers.
  3. As a portable 'Telex', able to communicate with other HUNTER's or data terminals.

Configuration

HUNTER's RS-232 serial interface is configured to represent a Data Terminal Equipment (DTE) for compatibility with Modems and other items.

Operation

First, check that the communication port is correctly initialised, see Communications Port Software.

Selection

From 'File Manager' select 'TERMINAL EMULATION' mode. You are now in HUNTER'S remote computer terminal emulation mode.

HUNTER is now ready to communicate.

The function keys are programmed as follows:

Fn 4....COMS
Fn 8....SYST

Keyboard entry causes characters to be transmitted, including control characters see ASCII Character Set.

Characters sent to the HUNTER will appear on the screen if printable. Upper and lower case alphabets are available.

Exit from Terminal Emulation mode is made via the 'SYST' function key.

Protocols

Any protocols selected will be observed by HUNTER's, communication software package automatically. Remember that block protocols like ACK/NAK will not transmit until 'ENTER' (CR) is pressed.

Buffers

It should be remembered that the HUNTER is fully buffered with transmit and receive communications buffers, a keyboard buffer and a virtual screen effectively keeping early information available for use.

At high receive data rates, e.g. 4800 baud, the receive buffer will remain full. If a "stop" is sent to the sending computer (e.g. XOFF or control S, sent manually) then the screen display will not stop immediately, continuing to display the characters stored in the receive buffer until the buffer empties. If this is found undesirable, the most straightforward solution is to reduce the data rate to 1200 baud.

If 2780 synchronous transmission is used in terminal mode, a block will be sent if the keyboard has not been operated for 5 seconds. This does mean that when using terminal emulation in 2780 mode for "signing-on", there should be no hesitation or typing errors or the block will be sent unexpectedly!

Auto Power Off

Terminal Emulation does not power off automatically. This is for ease-of-use when operating intermittently with a remote site. If auto power off were allowed, modems may drop the line resulting in messages lost, etc.

It is important, therefore, to remember to switch off HUNTER after using Terminal Emulation.

System Call

User programs can use Terminal Emulation which is provided as system call number 43 (see Hunter System Calls). Selecting "System" (function 8) in Terminal Emulation will return control to the calling program.

To use Terminal Emulation from Basic, the following is required:

1000 A=ARG(43);A=CALL(5)

Execution will continue after line 1000.

From a machine code or compiled program, a system call 43 is required, e.g:

.
.
LD C,43 ; select call
CALL 5
.
.