27C801 programming

[Guest]

Hi there,
I have a couple of questions on the 27C801 chip. I read through the forums and there was 1 reference to this particular chip but it still did not answer my question. I am familiar with using the S4 as i have used it for the last 10 years with great sucess. I have never had to program an 8mg chip before and i am really doing this as a favor for a friend. My S4 does have 512k memory. So my questions are as follows;

1. I have a master eprom i want to copy. When i do the load i set the memory to 00000-7FFFF#80000 is this correct?

2. I do the checksum on the ROM the last address is FFFXX and the checksum appears. Assuming the FFFXX is the additional memory area.

3. I send the file to the PC my file size is 1267kb which sounds correct for an 8mg chip.

4. I have downloaded the file splitter you recomended and have tried several diferent ways to burn the chip. But using the procedure you stated in a previous post (12/20/2006 @ 12:32:29 PM) i cannot program my S4 to the different memory areas to download. I am rather confused on this procedure.

5. Once the file is split....downloaded and burnt to the chip, how do i verify the checksum when the RAM checksum limits me to 00000-7FFFF?

ANY and all help will be greatly appreciated. Thanks in advance!

GMalicote

[Dataman (Neil Parker)]

Hi,

1. Doing as you describe will only load the second half of the memory device into the S4 user RAM.

What you need to do is load 00000-7FFFF#00000 to get the first half of the device into the S4 then either upload this to the PC for storage or burn it into the first half of your blank device (27C801?) Burn 00000-7FFFF#00000

Then with the master device back in the socket, Load 00000-7FFFF#80000. Which will load the second half of the device into S4. Again either upload this to the PC or burn it straight into the second half of your target device. Burn 00000-7FFFF#80000.

2. Taking a checksum of a device in the socket is independent of the S4 RAM. The S4 can quite happily SUM a full 16Mbit device. FFFFFh just happens to be the end address for the 27C801. (Note. FFFXX is displayed as the last two digits would be moving too quickly for the display)
You are correct in that you can only SUM the S4 RAM over the range 00000-7FFFF as that is the entire range of the RAM. To verify the target device you would SUM the fully programmed device which should match your master. (Note the two SUM keys on S4, Right one is for RAM left one is for device in socket)


I believe these answers should help with the remainder of your post. If not then please let me know.

Neil

[Guest]

Neil,
Thank you very much. Makes a little more sense now. I will give this a try and see what happens.

Best regards,
GMalicote

[Guest]

Neil,
Your directions worked perfectly. Thank you so much! Excuse my ignorance in this but i need to write instructions for my friend on how to do this on his S4 but the memory in his S4 is 128k. Would this be the memory addresses 00000,1FFFF,00000 - 00000,1FFFF,20000 - 00000,1FFFF,40000 - 00000,1FFFF,80000?

GMalicote

[Dataman (Neil Parker)]

GMalicote,

Almost. Remember 128K is only a quarter of 512k so you will need to program the device in eight segments as opposed to two with the 512k S4. The address ranges are therefore: 00000,1FFFF#00000 - 20000 - 40000 - 60000 - 80000 - A0000 - C0000 & E0000 both for loading the burning the device.

Hope this helps.

Neil

[Guest]

Neil,
Once again "Thank you", I will try this out with his programmer and see if I can do it. Should work fine. Thanks a heap for your help!

Best regards,
GMalicote