This article is about the British telephone device. See monologue for the other definition.

A Monolog is a Single Telephone Line Call Logging Device manufactured by British Telecom in the UK. The reason for connecting Monolog to a telephone line is to collect independent call and charging data to help resolve customer queries or complaints.

Monolog is usually connected to a customer's line at the telephone exchange although it is possible to monitor the line at the customer's premises.

Monolog is based around the Mitsubishi M50734SP-10 8-bit processor that uses an enhanced 6502 instruction set. The unit comprises two boards: a digital board that contains EPROM and RAM for storage of call records and an analogue board that provides the necessary interface components to the monitored telephone line.

Monolog is powered via four AA rechargeable batteries which are trickle charged at approximately 2 mA from a control line. This control line is also used for remote connection to the unit for the purposes of data retrieval.


Analogue Board

The analogue board provides the interface circuitry between the monitored and control telephone lines and the microprocessor. The board contains the following devices ;

U1 = OP490 Quad Op-Amp
U2 = Mitel MT8870CE DTMF Decoder 
U3 = Motorola MC145442 V.21 300Baud Modem
U4 = LM358N
U5 = Phillips 74HC157P

The board also contain a 25-way female D-type connector that provides the electrical interface to the monitored/control lines. Alternatively, it provides an RS-232 interface thereby enabling the direct connection of a PC running the Dialog software.

Battery Charging circuit

Monolog's batteries can be charged via 2 spare pins on the 25-way D-type connector; pin 4 (RTS) and pin 20 (DTR). If a 12volt power source is applied to either pin, the batteries are charged at 22mA. If both pins are used, the batteries are charged at 44mA. The 12volt feed is via two 330Ω current limiting resistors and the wired in fuse. This circuitry does not provide any protection against over-charging.

Digital Board

The digital board contains 7 Integrated Circuits as follows ;

U1 = M50734-SP10 Mitsubishi Microprocessor
U2 = 74HC373P address latch
U3 = CD4060BCN 14-bit asynchronous binary counter
U4 = 74HC139N Address decoder
U5 = Static RAM (130 kB)
U6 = 27C256BQ EPROM
U7 = Static RAM (32 kB)

In addition to these components are the reverse battery protection diode associated timing circuitry for the Processor and CMOS divider IC.

Real Time Clock

To enable the call records to be date stamped, the CMOS divider IC produces an interrupt pulse every 125 ms which activates the processor. The interrupt service routing updates the system clock and checks for any activity on the line. If there is none, the processor goes back to the SLEEP mode. In this mode, the CPU consumes very little power thereby enabling the unit to be battery powered. In its quiescent state, Monolog consumes around 180 µA while the monitored telephone line is inactive, rising to a peak of about 6 mA during a call while the DTMF decoder is on during the first 20 to 30 seconds of a call.


  1. British Telecommunications Engineering, Volume 8, April 1989
  2. Monolog Call Logger Installation Guide, Issue 2, 18 November 1994

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  • Monolog — Monolog …   Deutsch Wörterbuch

  • monolog — MONOLÓG, monoloage, s.n. 1. Scenă dintr o lucrare dramatică în care un personaj, fiind singur pe scenă, îşi exprimă cu glas tare gândurile. ♦ Monolog interior = procedeu literar specific romanului sau nuvelei de analiză psihologică, prin care… …   Dicționar Român

  • monolog — {{/stl 13}}{{stl 8}}rz. mnż IIa, D. u {{/stl 8}}{{stl 7}} ciągła wypowiedź jednej osoby; w dramacie: wypowiedź bohatera, będąca rozmową z samym sobą, skierowana bezpośrednio do widza lub czytelnika : {{/stl 7}}{{stl 10}}W dziele tym obok dialogów …   Langenscheidt Polski wyjaśnień

  • Monolog — Sm std. (18. Jh.) Entlehnung. Entlehnt aus frz. monologue, das als gräzisierendes Gegenstück zu Dialog gebildet wurde.    Ebenso nndl. monoloog, ne. monologue, nfrz. monologue, nschw. monolog, nnorw. monolog; Logik. ✎ DF 2 (1942), 145; Cottez… …   Etymologisches Wörterbuch der deutschen sprache

  • Monŏlog — (v. gr.), Gespräch mit sich selbst, wobei Eine Person als Subject u. Object sich denkt od. gedacht wird; kommt bes. im Drama (s.d.) vor. Er versinnlicht, im Gegensatz vom Dialog (s.d. 2), den hohen Drang u. Kampf der innern Gefühle u.… …   Pierer's Universal-Lexikon

  • Monolōg — (griech., »Alleinrede, Selbstgespräch«), im Drama im Gegensatz zum Dialog eine solche Szene oder Rede, in der eine einzelne Person für oder mit sich selbst spricht. Über die Berechtigung des Monologs, den schon Gottsched in seiner »Kritischen… …   Meyers Großes Konversations-Lexikon

  • Monolog — Monolōg (grch.), Einzelrede, Selbstgespräch …   Kleines Konversations-Lexikon

  • Monolog — Monolog, Selbstgespräch im Drama oder. in einer andern Dichtung. Das dramatische Selbstgespräch darf, da es den Gang der Handlung unterbricht, nie allein Reflexion sein, sondern muß auf das Kommende spannend vorbereiten. B–l …   Damen Conversations Lexikon

  • Monolog — Monolog, das Selbstgespräch z.B. im Drama …   Herders Conversations-Lexikon

  • monòlog — m 〈N mn ozi〉 1. {{001f}}knjiž. kazal. film. duži dramski tekst jednog dramskog lika, govori ga sebi i publici; samogovor 2. {{001f}}razg. pejor. duži govor, dosadno izlaganje …   Veliki rječnik hrvatskoga jezika

  • monolog — monòlog m <N mn ozi> DEFINICIJA 1. knjiž. kazal. film. duži dramski tekst jednog dramskog lika, govori ga sebi i publici; samogovor 2. razg. pejor. duži govor, dosadno izlaganje ETIMOLOGIJA mono + log …   Hrvatski jezični portal

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