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ECB Bus Monitor


The ECB bus monitor is a debugging/prototyping card which allows a builder to monitor the state of the ECB bus. The ECB bus reflects the state of the the SBC or processor card plugged into the bus so it is helpful to understand the proper operation of the computer system.

ECB bus monitor features:

  • Displays state of ECB bus address lines [A0-A15], data lines [D0-D8], and control lines using LEDs
  • Allows the builder to single step through instructions
  • Allows the builder to set “trap” address to halt the SBC processor when a specific address is reached
  • Allows the builder to set conditional trapping combinations including on memory and I/O requests

Note: Newer RBC processor cards have extended the address and data lines beyond what this card can display. It is most useful with the Z80-based SBC/processor cards.

This board was derived from information in an article published in

Hardware Documentation

Build Information

Parts List

LED Labels

Default Positions of Switches

From: Don Caprio <>
Date: Sat, 02 Apr 2011 16:22:25 -0700
Local: Sat, Apr 2 2011 7:22 pm 
Subject: Re: [N8VEM: 9121] Re: ECB Bus Monitor

Hey, I got my bus monitor working. That is lights blink, status and data LED's 
are responsive. Address LED's flicker during boot and running CP/M commands. 

This was totally a high tech approach :) I looked at the home page of the N8VEM. 
You see a picture of the bus monitor. If you look very closely you can pretty much tell 
what the position of the switches are. I set mine as pictured and it now it works. 
I still would like to know what the switches are and what functions they provide. 

Set all address switches to ON (SW_1_2 & SW_3_4). 

On the remaining two dip switches set them all to OFF. 
Turn switch position 5 ON  (SW2) 
Turn switch position 4 and 5 ON (SW1) 

Videos Demonstrating Operation

See the ECB Bus Monitors Videos page for a set of videos showing the operation of this board.

File List

FilenameFilesizeLast modified
bus_monitor_parts_list_clean.pdf42.9 KiB2015/11/03 01:17
bus_monitor_parts_list_clean.xls26.5 KiB2015/11/03 01:17
busmonitor_ger.zip9.5 KiB2015/11/03 01:13
ecb_bus_6_english.txt17.8 KiB2015/11/03 01:09
ecb_bus_6_german.txt22.3 KiB2015/11/03 01:13
ecb_bus_monitor_default_switch_settings.txt856.0 B2015/11/03 01:09
ecb_bus_monitor_layout.pdf737.9 KiB2015/11/03 01:09
ecb_bus_monitor_schematic.pdf127.8 KiB2015/11/03 01:09
ecb_busmonitor-003.zip167.5 KiB2015/11/03 01:09
ecb_busmonitor-full-brd.pdf649.0 KiB2015/11/03 01:09
ecb_ct_bus_monitor.pdf29.5 MiB2015/11/03 01:09
ecb_led_labels.xls33.5 KiB2015/11/03 01:09
boards/ecb/bus-monitor/start.1456601916.txt.gz · Last modified: 2016/02/27 14:38 by admin
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