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IBM 3780 Data Communication Terminal
Like the IBM 2780, the IBM 3780 Data Communication Terminal is a control
unit with a set of input and output devices. The IBM 3780 has the
following hardware elements:
* A control unit, a BSC adapter and buffers.
* A card reader capable of reading up to 600 cards per minute.
* An optional card punch capable of punching up to 359 cards per
minute.
* A line printer capable of printing up to 425 lines per minute.
The IBM 3780 is capable of the following:
* Transmitting or receiving in ASCII or EBCDIC.
* Accepting horizontal tabulation codes, making it possible to process
line printer output more efficiently.
* Accepting vertical forms control codes, allowing the formatting of
line printer output.
* Transmitting or receiving data in the transparent mode, making it
possible to transmit or receive binary data (optional on the IBM 3780
and applies only to the EBCDIC mode).
* Truncation of short records, enabling suppression of trailing blanks
from card input, resulting in increased transmission efficiency
(performed automatically; the user does not need to include EM or IRS
control characters in the data).
* Compressing blank fields within the data, increasing transmission
efficiency (performed automatically by replacing blank fields with a
two-byte control sequence).
* Transmitting or receiving blocked data, thereby increasing
transmission efficiency (maximum number of records allowed per block
is 255 in the nontransparent mode and 1 (optionally 6) in the
transparent mode).
* Interleaving the data passed between the communications line and
the input/output devices by using two 512-byte buffers,
increasing general transmission efficiency.
* Generating Wait-before-transmit ACKnowledgement (WACK) and
Temporary Text Delay (TTD) control character sequences when it is
temporarily unable to transmit or receive data.
For a detailed description of the IBM 3780, refer to Component
Information for the IBM 3780 Data Communication Terminal, IBM SRL
GA27-3063.