Downloads
All files available for download are listed below. EPROM images are provided as Intel HEX files. Software is provided as-is for archival and research purposes.
EPROM Images
| File | Description | Notes |
|---|---|---|
| Monolog_MK1_EPROM.hex | Mark I EPROM — original image | Standard 10-digit NUM field |
| Monolog_MK1_EPROM_11digit_NUM.hex | Mark I EPROM — patched image | NUM field extended to 11 digits for current UK numbers |
11-Digit Patch
The patched EPROM modifies four bytes at addresses $444F, $4475, $644F and $6475, changing the NUM field limit from $0A (10) to $0B (11). All other firmware behaviour is unchanged.
Software
| File | Description | Platform |
|---|---|---|
| dialog.py | Python DIALOG reimplementation for Mk II RS-232 | Python 3 · Windows |
| dialog2.py | Variant Python implementation | Python 3 · Windows |
| DIALOG.EXE | Original DOS DIALOG comms program | MS-DOS |
| CHECKLOG.EXE | Original DOS charge verification program | MS-DOS |
| PRINTOUT.EXE | Original DOS print utility | MS-DOS |
PCB Gerber Files
Gerber files for both Monolog PCBs, suitable for manufacture or inspection in any standard PCB CAM tool.
| File | Description | Link |
|---|---|---|
| analog_pcb.zip | Analogue PCB Gerber files — modem, line interface, DTMF decoder, RS-232, D-type connector | Download |
| digital_pcb.zip | Digital PCB Gerber files — CPU, RAM, EPROM, real-time clock, reverse battery protection | Download |
Monolog Documentation
| File | Description | Link |
|---|---|---|
| Monolog_Call_Logger_Handbook.pdf | Original BT handbook — Issue One, 24 Jan 1990 | Download |
| Monolog_MK1_Disassembled_v6.txt | Annotated Mark I firmware disassembly | Download |
| Monolog_Mk_II_Disassembled_v1.txt | Annotated Mark II firmware disassembly | Download |
Meter Control Equipment (MCE) Documentation
Historical BT documentation relating to the Meter Control Equipment and the 60V AC SPM supply — the exchange-side equipment that generated the meter pulses Monolog was designed to detect.
| File | Description | Link |
|---|---|---|
| Meter_Control_Equipment_Oct_1983.pdf | MCE technical description — October 1983 | Download |
| Meter_Control_Equipment_Shelf.pdf | MCE shelf layout and apparatus schedule | Download |
| MCE_Rack_Common_Services_AT80130.pdf | BT Specification T80130 — Rack Common Services, MCE | Download |
| Rack_Common_Services_Meter_Control_Equipment_AT80130.pdf | Rack Common Services MCE — apparatus and cabling | Download |
| BT_Metering_System.pdf | British Telecom Metering System — overview of charging groups, tariff rates, Clock 36 pulse generation, Local Call Timing and STD metering distribution | Download |
| 60V_AC_SPM_supply.pdf | 60V AC SPM supply circuit — exchange metering power source | Download |