wiloson

Wow, thank you for this. I found that 3 NOP worked best for me with it failing more at 2 and 4. I had to increase the MHz to 255MHz before I was able to pass all the memory tests. I will probably try upping the MHz to see when it starts to fail again and choose something in the middle and then reduce the NOPs to 2 or 1 to see if it will work.

I'm starting to suspect that the power supplies on both of my computers are a little too noisy to run this board. I looked at the schematic of the TI power supply and I was surprised that the +5Volts supply is fed off of the 7812 regulator. I was thinking of replacing the 7812 and 7905 regulators with switching regulators like the N7812-1PH , as well as replacing some of the caps, but it may be better to replace the power supply with something newer. What power supply did you replace your original supply with?

my two computers are silver and black LTA2383 and my original system LTA4582. They don't seem far from what others have as far as manufacturing dates.

I have put together 5 of the second version(with R4) boards and the only version of the firmware that passes the SAMS test for me is the 252Mhz with 3 NOPs that you published on Feb23. Is it possible for you to compile two versions of this software one for the 2GB and the other for the 8GB mod? I purchased APS6404L-3SQR DRAM chips, the PI Picos from reputable suppliers and I have tried both of my older consoles (I opened one up and the power supply was good) and only one firmware worked. I wonder if the date my computers where manufactured has something to do with it.

What is the status of the pcode card? I tried running the "call pcodeon" command and it just booted into the Pcode colour screen and sat there without any text. I have the required Pcode.rom and Pcode.grom files in the root of the SD card...

I got the board working last night. I was working on the original parts list and installed a 10k ohm resistor into R4 instead of a 470 ohm. I noticed that the clock signal was horrible and I couldn't find any mention of the 470 ohm resistor in the parts list as per your comment. After searching the discussion I found your post about the change to r4. Thanks, everyone for your help getting this board going.

The first two pins you circled aren't used and I have checked all the solder joints with a microscope so I am confident that they are good. The glare from my lamp and my camera makes all the solder joints look suspicious but I assure you that they are good. I will reflow the solder on all the pins on the SD card holder tonight just to be sure, and see if I can verify that the SD card makes good contact with the cardholder when it is inserted. Then I will check the communication at the SD card holder with my scope and see if any of the data lines are bad. I will then then try swapping the pull up to 330 Ohm resistor instead of a 470 Ohm. Thanks for all the help

well no luck with reformatting the SD card. I still get the LED flashing 4 times. here is an image of the assembled board.

I think that the SD card may be set up as GPT and it should probably be MBR. I'll have to wait until I get home, after work today, before I can verify this and make changes. If this doesn't help I will change the pull-up resistor to 330 ohms. I'll also add a photo of the board tonight as well. thanks

i seem to be getting 4 flashes saying that it cant see the primary FAT partition. I used diskpart to clean the SD card and formatted it as default FAT 32 but it still is giving me the same error. I have tried a different SD card and tried to resize it to 8gb and formatted it using different software tools and still no luck. I'll try again tomorrow night. thanks for all the help.

I completed my first PPEB board today and it doesn't seem to be working 100%. When the pico boots up the LED blinks 4 times but the "call tipi" command gives an error. Without the SD card the LED only blinks 3 times so the it is reading something from the SD card. The Pico is not a clone and the micro SD card is a new FAT formatted premium 32GB verbatim card. The "call say" works so there must be good communication between the TI99/4A and the PPEB. I'm using the latest DSR and a later version of PPEB2_264. Any advice on what combination of software and DSR would work the best? thanks

Does anyone in Canada want to build this project with me? I can order the PCB and assemble & test but it's cheaper to build if we order a batch of 5 or more. I'm located in Toronto.