MCUmall EPROM BIOS Chip Burner Forum
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 True USB Willem Programmer (GQ-2X, GQ-3X, GQ-4X)
 How to read 8-bit only 2M Mask ROM?
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callanbrown

Canada
3 Posts

Posted - 06/03/2016 :  13:39:37  Show Profile  Reply with Quote
Hello,

I have a 40 pin MASK ROM, similar to 27C4096. However, it can only run in 8bit mode. Reading it in 16bit mode causes errors for some reason. Please see this part of the schematic:

h**p://i.imgur.com/FS2a0RR.png

The one on the right (19H) reads OK. The one on the left (13H) reads bad. Notice that pin 31, which is /BYTE on 27C2048 is not present on either one, meaning they have set the mode in factory.

Can you help me with this?
Reply #1

ZLM

2923 Posts

Posted - 06/05/2016 :  12:11:43  Show Profile  Reply with Quote
If your chip has been set to 16bit mode,then you have to use 16 bit mode to read.
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Reply #2

callanbrown

Canada
3 Posts

Posted - 06/09/2016 :  07:14:59  Show Profile  Reply with Quote
Hi,

Sorry, I made a mistake, the correct pinout is 27C400. But regardless, the problem is that I want to read this 8/16bit chip in 8 bit mode - how can I accomplish that? I believe if I select 27C400, it asks for the 16-bit adapter and tries to read in 16-bit mode. So every other byte is FF.

Can I force 8 bit mode?
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Reply #3

ZLM

2923 Posts

Posted - 06/10/2016 :  15:10:37  Show Profile  Reply with Quote
For the 27C400, the programmer needs ADP-054 adapter. And the adapter used 16 bit mode to read. No way to change it.

As I know there is no data differences if you read it in 8 bit or 16 bit.
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