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RetroJunkie
Australia
3 Posts |
 Posted - 10/12/2013 : 20:32:41
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Hi everyone,
I've been having some trouble reading a D23C4000 which is apparently pin compatible with the D27C4000 according to the datasheet here - h**p://www.ic-on-line.cn/view_download.php?id=1574048&file=0288%5Cupd27c4000gw-15_714400.pdf
The problem is the data is not being read consistently, the checksum is changing with each read of the chip which is probably not a good thing. I'm using the GQ-4X with the ADP-054 16-bit EPROM adapter.
Does anyone have any ideas or workarounds for this sort of behaviour? Even if you have encountered the same behaviour yourself, just letting me know I am not alone would be a great comfort.
If it just can't be read using the GQ-4X, that's not a problem - I understand it isn't listed on the compatibility listing even though it is pin compatible with the D27C4000 which is listed.
Thanks in advance to anyone who might be able to help! |
RetroJunkie.net - Where it is party time, all the time. |
Edited by - RetroJunkie on 10/12/2013 20:41:59
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| Reply #1
ZLM
2945 Posts |
Posted - 10/13/2013 : 07:53:58
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Try to change the compatibility jumper J5 on the adapter between V3/V4.
The problem may be related to the power.
Also, make sure all pins are contacted good between chip and adapter, adapter and the programmer ZIF.
Jiggle the adapter and chip after they are locked, to reduce the contacting problem. |
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| Reply #2
RetroJunkie
Australia
3 Posts |
Posted - 10/13/2013 : 15:53:03
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Ah yes, the jumpers I did give them a go without any success. Power though, got me thinking...
I may have read the ROM successfully using a VCC of 3.6V instead of 5V - will let you know once someone else has verified :)
Thanks for the tip and keep up the great work! :D |
RetroJunkie.net - Where it is party time, all the time. |
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| Reply #3
RetroJunkie
Australia
3 Posts |
Posted - 10/14/2013 : 02:35:51
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Yep, looks like it was read successfully! Checksum is OK on two out of two chips :D
One of your other replies on another post helped me put it all together and sing a chord of C.
Thanks for the help once more! |
RetroJunkie.net - Where it is party time, all the time. |
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Topic |
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Reading an NEC D23C4000 / D27C4000 on GQ-4X
