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FAQs about EB-251

ROMless Operation

1. How does the system work in ROMless mode?

ROMless operation means that the chip selected is for example 80C251SB, and ports lines are the bus. Instructions are fetched from the EB-251 emulation memory if addresses are below the boundary defined in the Options Menu (4K, 8K, 16K, 32K and 64K). Above the boundary, instructions are fetched from your target circuit, so you must have the emulation header connected to a working circuitry.

ROMed Operation

2. How does the system work in ROMed mode?

ROMled operation means that the chip selected is for example 87C251SB, and ports lines are not affected by instruction fecth cycles.


3. I cannot access (read or write) Port 0 and 2.

Select chip type ROMed (like 87C251SB) and not ROMless (like 80C251SB).


4. How many timer ticks are lost while stopping the emulation and reassuming it?

As the system uses a bond-out chip, no ticks are lost while stopping the emulation.

System Problems

5. Yesterday I worked with the system and it was OK. Today the ports are not showing any activity.

The software has been invoked without a EB-251 system connected to the power supply; then the mode has changed from Emulation to Simulation and therefore you are working only with the simulator.

6. I cannot establish a communication between the system and my PC, although the serial port of my computer works with another system as well as the serial cable.

a) A cable from another system may be the problem. Use only the black cable supplied with the system.
b) Your PC does not support the high baud rate. Try to set the baud rate to low in the Options Menu.

7. The system shows always Error #6 - crystal problems.

Set the crystal jumper to 14.745 MHz.

8. The system does not work at 20 MHz.

The Intel bond-out chip may not always support that frequency.


9. Why cannot Port 0 and 2 be accessed in the watches window, etc.?

Select chip type ROMed (like 87C251SB) and not ROMless (like 80C251SB).

10. Why some options are grayed out?

Not available yet in the current software version.

11. I cannot open the Module Window.

You did not load a file with DEBUG information. Check again how the file has been generated and if you selected the appropriate vendor in the Load command.

12. Windows is reporting error code out of memory, etc., when I try to open any dialog or window.

The error code may be caused by incomplete setup. Please copy BWCC.DLL from ceibo directory to your Windows system directory (i.e. WINDOWS\SYSTEM or WIN95\SYSTEM).
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