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FAQs about DS-51

ROMless Operation

1. How does the system work in ROMless mode?

ROMless operation means that the chip selected is 80C31, 80Cxx, etc., and ports 0 and 2 are the bus. Port 0 can only be used as AD0-7 address/data bus lines. Port 2 can only be used as A8-15 address lines.

ROMed Operation

2. How does the system work in ROMed mode?

ROMed operation means that the chip selected is 83Cxx, 87Cxx, 80C51, etc., and ports 0 and 2 are I/O ports. Port 0 can only be used as I/O port. Port 2 can only be used as I/O port. Ports

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

Select chip type ROMed (like 87C51) and not ROMless (like 80C31).


4. I replaced the microcontroller and the system does not work.

DS-51 may accept many different derivatives. DS-51 uses standard microcontrollers working in emulation mode. This special mode used by the emulator in ROMed mode, outputs the internal buses and it is not documented in the Philips Microcontroller Data Book. Programming the security bits is the operation required by the chip to accept entering in the emulation mode. If you cannot program the security bits or you are not using a Philips microcontroller, select in the software menu a ROMless type (i.e. 80C32, 80C51FA, etc.) and not ROMed (i.e. 87C51FB, 87C...., etc.).

5. Which security bits should I program, if I replace the microcontroller ?

Use Philips microcontrollers and program lock bit 1 and 2 only. Do not program lock bit 3.

6. How can I program security bits ?

Use Ceibo MP-51 or any other programmer with similar capabilities.

System Problems

7. 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 system connected to the power supply; then the mode has changed from Emulation to Simulation and therefore you are working only with the simulator.

8. 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.

1. A cable from another system may be the problem. Use only the black cable supplied with the system.

2. Your PC does not support the high baud rate. Try to set the baud rate to low in the Options Menu.

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

Set the crystal jumper to Internal.

10. I get a communication error with the DOS debugger but with the Windows debugger everything works.

Check the COM port setup in the Options Menu.

11. I get error error #4 and #5 with the DOS debugger but with the Windows debugger everything works.

Check the Chip type setup in the Options Menu.


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

Select chip type ROMed (like 87C51) and not ROMless (like 80C31).

13. Why some options are grayed out?

Not available yet in the current software version.

14. I am using BSO/Tasking assembler and when I try to enter a symbol in the Watches window, I get Error #311 and the values of the variable are represented as question marks (?????).

This assembler and many others are case sensitive, so enter the variable manually and always in upper case.

15. 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.

16. Probe C752 does not work with my interrupt routine.

Probe C752 uses an 87C752 to emulate 8XC750/1 microcontrollers. The main software difference between both types of chips is found in the Interrupt Enable Register (IE - address A8h). The ETI bit of the IE Register has different addresses. DS-752 locates the ETI bit at bit address ADh, while 8XC750/1 chips have that bit at address ABh. Therefore, if you are emulating an 8XC750/1 with the 87C752 you have to tell your assembler or high-level language compiler that the target chip is an 8XC752 to generate the file for the emulator. After you finish to debug the software redefine the target chip as an 8XC750/1 and recompile it to generate the file for the 8XC750/1 programmer. Again, the above manipulations are only necessary if your software is using the ETI register bit for an 8XC750/1. The 87C748 is equivalent to the 87C750 and the 87C749 is equivalent to the 87C752.

17. Which file should I load while using Keil software.

Load the output file from the L51 or BL51 linker. The file has no extension as default, although you may change the extension in the linker command.

18. Why the Code Dump Window dispays several times the same addresses?

Adjust the window size. The emulated microprocessor also sets the program counter to 0 while overflowing its maximum address (FFFFh or less according to the chip type).

19. Interrupts and Timers are not working in simulation modes.

Use real-time emulation mode for Interrupts and Timers. This support is not fully implemented yet in your current software version.

20. How can I see the modules list in Ceibo's Debuggers ?

1. Make sure, that the absolute file includes debug info.

2. If the source files and the absolute files are not located in the same directory, set properly path for source files, using menu item 'Options->Path for source' in Ceibo Debugger.

3. If you still cannot see the modules, find it yourself.
1)Open dialog window 'Options->Module list file';
2)press button 'File find...';
3)check the checkbox 'Absolute path'from the right of the dialog window;
4)change file type to 'all files(*.*)';
5)find your file and choose it;
6)press OK(you will see the choosen module with * from the left);
7)click on the module and press OK;
8)go to the 'View->Module'window(the menu 'Module' will be active);
9)click on the module and you can debug;

4.Notes: you need the files with extension .lst only if you deal with PLM language.

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