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One for the hardware guys


Willsy

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Can anyone help Bill Sullivan over on the TI Mailing List (yahoo) with his GramKracker problems:

 

 

 

Hi Bill,



Based on your observations, the problem may not be with a ram chip, but with a logic chip. If multiple bytes are being altered when you change one, a 'switch' in one of the logic chips may not be turning off. You may want to change out the logic chips that affect Grams 1 & 2, as well as the associated Ram chip.

Tony

On 11/8/2013 3:44 PM, Bill R Sullivan wrote:

 

 

Well it looks like some of my fun hobby times are coming to an end, as GRAMS 1 & 2 are no longer holding all of their loaded code for more than a few minutes. Specifically the E/A CALLs added to TI BASIC by Rich Gilbertson and modified by Tursi for MSAVE'd BASIC programs. Even if I use it for BOOT MENU which only needs to be switched in for the transfer to high memory, and then switched out, eventually gets corrupted.

Previously before I moved to Bullhead City (BHC) I believed I was causing it by using the GK reset switch, and due to the fact that GRAMS 1 & 2 are not protected by the RAM Bank 1/2 protection switch as all other GRAM & RAM are, but the BOOT MENU corruption proves that is not the case.

This prompted me to test GRAMS 1 & 2 using the GK memory editor. Filling >g2000->g5FFF with >FF was 100% OK, but filling both GRAMS 1 & 2 with >00 was not good at all. especially GRAM 2, >g4000->g5FFF had many random locations showing >20, and trying to change one address caused other addresses in the GK view to change to >20 from >00 or from >20 to >00 in the view. I don't seem to have any problems with GRAMS 3-7 or 0, but I'm not currently using a modified GROM 0 (OPSYS), but have considered loading a true lowercase character set there.

As the GK manual doesn't inform me as to what the 8K GRAM chips that are used for GRAM 0-2 are, I was hoping some one in the community could tell me, as I haven't had to open up my GK to change batteries since I modified it to change out the battery through a hole in the bottom of the case. I would prefer to wait until I have the replacement chips first. I might also need to know where I can purchase the chips if someone knows what they are. Please help me if you can, as this GK is my most important peripheral for my CF7A+/NanoPEB systems.

 

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