WebEE

The main software of interest for this project is spread over two programs, "EMULATE.EXE" and "HEX-CONV.EXE". The first of these is the main control software for the emulator, while the second converts various industry standard hex file formats to and from the EPROM emulator format.

Additional programs on the disk are "PROGRAM.EXE" which controls last months EPROM Programmer, and "SPLIT2.EXE" & "SPLIT4.EXE" which divide Intel hex files into 2 or 4 files for 16 and 32 bit systems respectively. Since the full BASIC source code is given for all of these programs, it would be possible to create one large program containing all the facilities - if someone had more time than me!

When "EMULATE.EXE" is started, the Device Selection Menu will appear. From here you choose the type of device you will be using, either 2764, 27128, 27256 or 27512.

Once you have chosen the device required, the Main Menu will appear. Option 1 allows you to upload hex data to the emulator. The hex data is saved and loaded ASCII-Text format which is peculiar to this software. "HEX-CONV.EXE" will convert to and from this format.

When Option 1 is selected you will be told where to set the switches on the emulator. You will then be asked for a filename, simply enter 8 the alpha-numeric characters - the extension is fixed to .HEX and does not need to be typed. Now sit back and wait, the progress will be shown on the screen.

Option 2 allows you to change the EPROM type as previously. Option 3 lets you run the Hex File Convertor program, "HEX-CONV.EXE" and option 4 lets you access a DOS Shell, type "EXIT" to return to the emulator. To quit the emulator, press Escape.

The Hex File Convertor was described in detail last month, so I won't bore you by repeating it here!

Emulating
The emulator may be powered by the microprocessor circuit being tested if there is sufficient capacity in the power supply. This will happen by default, via pins 14 and 28 of SK2.

If you need to power the emulator separately, you will need to isolate pin 28 of SK2 from the circuit under test, to prevent the two power supplies conflicting. This is easily achieved by removing pin 28 from a spare IC socket, and then fitting this onto the free end of the ribbon cable before plugging it into the test circuit.

The 300mm length of ribbon cable should not cause any problems unless the microprocessor system is very fast. In this case, try making another cable just long enough to reach.

The ICs interfacing this unit to the outside world are 74LS TTL devices, since these are somewhat more robust than 74HCT, and the inputs are not so static sensitive. For speed critical systems you may need to use a different logic family here.

When the unit is not in use it would be a good idea to plug the end of the ribbon cable into a piece of anti-static foam. This will help protect the electronics from static, and prevent the pins from being bent.