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Post by Scott McDonnell on Dec 4, 2004 14:59:36 GMT -5
On the side of the board that is lable one solder spot says "TMODE" Does any one know what this one is for? Jeri has said this stood for "Test Mode". I connected it to ground the other day and it just reset the DTV. I need to test this tonight, but I think it do a soft-reset (meaning it leaves the contents of RAM intact.) Useful for troubleshooting. On some of the units, the TMODE pin is connected to the D Flip-Flop using wires (maybe being used as a watchdog circuit?) I have one that has this wired up and one that does not. Anyway, I will see if I can figure out what it is doing. Scott
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Post by Hacking the ROM on Dec 4, 2004 15:12:18 GMT -5
Alright, I've done the keyboard. I've done the IEC. I've mapped out the reset pins and the joystick pins (to connect up an external joystick.) Next up is to hack the ROM. I spent about 2 hours last night tracing lines into the ROM blob, before my eyes were getting tired. Here's what I have so far: home.comcast.net/~netsamurai/ROM_Pins.jpgI need A4, A7, A16, VCC, VSS, CE(s), and other control pins. All pins except the CE "should" also be connected to the RAM chip, for which we have a pinout: www.zmd.de/pdf/UL62H1708A.pdfOnce we have all the pins, we can dump the ROM, examine the filesystem and see if we can replace it with some type of flash system. BTW, here's the rest of the hook ups: home.comcast.net/~netsamurai/Hook-UP.jpgWe should also connect up the reset to the IEC line, to reset the floppy drives. If you reset the DTV while the drive is connected and on, it will lock up the DTV. I have found that 30AWG wirewrap wire fits nicely into the vias, so we can wire into the rom without destroying the board. I also believe we can isolate the ROMs power, so we don't have to upset the rest of the circuit. I bought 4 units, one of them is dedicated to be destroyed if necessary for reverse engineering purposes(planning to attempt to disolve the blobs at some point.) I will be working on this more tonight and will post if I discover any more. Please post or email me if you find anymore of the ROM pins. Scott McDonnell netsamurai@comcast.net
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Post by Scott McDonnell on Dec 4, 2004 21:37:55 GMT -5
Well, I did a simple test to check if the TMODE pin soft-resets. It doesn't look like it does. I poked a value into 2048, then reset via TMODE and then looked at the value for 2048 and it was 0 again. Oh well...not sure what it does. It could still be a watchdog circuit. I suppose I could trace it back to the flip-flop and figure it out, but I think I will save that for another night. ATM, I am more interested in getting the ROM hacked.
Scott McDonnell
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Post by core321 on Dec 5, 2004 21:37:09 GMT -5
Hi Ian, Got a question about the Entropy demo. I loaded it through the joystick method and used: 0 Poke1,55:Load"Entropy",1 It runs and no problems or is there? I visited your site and saw your picture of the Entropy demo. My demo does not have the screen you have. Unless I can't see the whole demo from the joystick. Do you need to press space at any time of the demo? If so then that is the problem. I have no skills in doing the hacks to the DTV and I don't plan on to because I don't want to ruin my DTV. Maybe I will get someone to help me. Let me know if I am missing part of the demo. Thanks, Mike
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Post by Draeyoc on Dec 5, 2004 23:03:31 GMT -5
Regarding the Entropy demo using a stock (unmodified) stick:
I've successfully simulated the space bar by holding down the A button and then tapping the joystick to the up position. There are multiple pages to the Entropy demo and you should be able to view them all with the sequence I've described. Let me know if it works for you.
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Post by core321 on Dec 6, 2004 0:52:32 GMT -5
Regarding the Entropy demo using a stock (unmodified) stick: I've successfully simulated the space bar by holding down the A button and then tapping the joystick to the up position. There are multiple pages to the Entropy demo and you should be able to view them all with the sequence I've described. Let me know if it works for you. Draeyoc, Thanks for the info. It works like a charm. Thanks again, Mike
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