 Advanced programmable interrupt controller |
| According to the present invention, a computer system includes an advanced programmable interrupt ... |
|
| Low speed serial bus protocol and circuitry |
| OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, the computer system C according to the ... |
|
| Serial bus system for sending multiple frames of unique data |
| Accordingly, the present invention discloses a computer system including a processor, a memory ... |
|
| Data routing using status-response signals |
| The present invention provides an apparatus and method for routing data between multiple bus ... |
|
| Data and data strobe circuits and operating protocol for double data rate memories |
| What is claimed is: 1. A computer populated with a plurality of double data rate DRAMS including a ... |
|
| Non-volatile, electrically erasable and reprogrammable memory element |
| We claim: 1. A non-volatile, electrically erasable and reprogrammable memory element comprising a ... |
|
| High speed processing flip-flop |
| A high speed processing flip-flop contains a header circuit and a pulse flip-flop circuit. The ... |
|
| Compact multifunction logic circuit |
| The invention is a multifunction logic circuit, offering low power operation and compact layout.... |
|
| Semiconductor storage device with redundancy arrangement |
| axi' An object of this invention is to shorten an access time in a semiconductor storage device ... |
|
|
Interface module for telephone lines
| Details |
Inventors: Froment, Jean-Claude; Pantani, Jean-Pierre; Verhaeghe, Michel;
Assignee: International Business Machines Corp. (Armonk, NY)
Primary Examiner:
Assistant Examiner:
Attorney, Agent or Firm:
A monolithic module acting as the interface between a modem and leased ("LL") or switched ("SL") telephone lines, mainly characterized in that: 1. It can be formed on a silicon chip (due to the absence of electromechanical relays or similar switching means), and 2. Its architecture is such that it makes it possible, by interconnecting or "stacking" identical modules, not only to attach additional telephone lines, but also to increase the number of allowable modem configurations. The module (10, 10') comprises two controlled-type line amplifiers (DLL, DSL) which exhibit a high output impedance regardless of whether the power supplies are "on" or "off"; two controlled-type line receivers (RSL, RLL) which provide a very high input impedance whether the power supplies are "on" or "off"; and a wrap receiver (WRP) for testing the modem (to the exclusion of the telephone lines) and interconnecting or "stacking" identical modules. The figure shows an embodiment wherein two of the modules are interconnected; various configurations can be obtained depending on the logic state of the control inputs (1 to 4 for module 10 and 1' to 4' for module 10') supplied by the modem. |
|
DETAILED DESCRIPTION OF THE INVENTION 1.
Architecture of the Basic Module FIG.
1 is a schematic diagram of the architecture of two identical modules 10 and 10' in accordance with the invention.
Module 10 includes two line amplifiers DLL and DSL, respectively, associated with a leased line labeled TXLL and a switched line labeled TX/RX SL.
The inputs of these amplifiers are connected to a common node labeled TX DATA that receives the data to be sent over the transmission lines of the modem.
Two receivers RLL and RSL receive the data sent over a leased line labeled RXLL and over switched line TX/RX SL, respectively.
The outputs of these receivers are connected via a common node labeled RX DATA to the receiving portion of the modem.
Although the switched line TX/RX SL shown in FIG.
1 is intended to represent a four-wire full-duplex line, it should be understood that this could be replaced by a couple of two-wire half-duplex lines respectively used for transmitting and receiving signals.
Module 10 also includes an additional receiver labeled WRP which is identical to receivers RLL, RSL and is disposed between common node TX DATA and a node labeled WRP OUT.
Receiver WRP is an important component in that it is used, in particular, to interconnect identical modules when "stacking" is desired.
Receiver WRP is identical to RLL and RSL, but is never connected to PTT lines.
It will be observed that module 10 includes no switching circuits such as relays, and that the amplifiers and receivers are controlled circuits in the sense that their operation is dependent upon the logic levels applied to the control inputs designated 1, 2, 3 and 4.
The implementation of these circuits will be described later in detail.
Inactive circuits are placed in a high impedance state.
Two identical modules 10 and 10' are shown in FIG.
1 because, as will be explained, they can be combined to meet the individual requirements of various modem configurations, thereby demonstrating the advantages of said architecture.
2.
Line Amplifiers In order to eliminate the switching circuits (or relays), this invention discloses the use of a line amplifier exhibiting an output impedance much higher than 600 ohms, regardless of whether the modem is in the "on," "idle" or "off" state
|
|
I/O Systems 
