Offsets when burning different EPROMS

EPROM EEPROM SRAM NVRAM Flash chips, reading/writing hardware and software
vp304
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Re: Offsets when burning different EPROMS

Post by vp304 »

Sorry for the 5 year old thread bump, but didnt want to start a new thread.
Have not burnt a chip in 7 to 8 years and little rusty.
Have read the getting started guides etc etc

So i have a 12p 32k tune i done for a friend to get his car going.
is in a vn commodore if i remember right is a 27c128 chip ?
Does the 12p 32k file tune need to be stacked or can i just uv erase his standard chip and burn tune straight as is without stacking it?
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Re: Offsets when burning different EPROMS

Post by yoda69 »

27c128 is only 16K memory, need a 27C256 which is 32K or stack files for a 27C512 which is 64K.
vp304
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Re: Offsets when burning different EPROMS

Post by vp304 »

Dammmm
Thought that mighta been the case
Kinda in the crappa now as don't wanna go to all the work of soldering another eeprom to the memcal
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Re: Offsets when burning different EPROMS

Post by antus »

I'd recommend to cut the old eeprom off, rather than desolder it, and solder a socket in to the top of the chip so you can just plug it in without risking heat damage to the new chip.
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vp304
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Re: Offsets when burning different EPROMS

Post by vp304 »

Owner had a spare vs v8 chip
So i was laughing
My uv eraser took around 8 to 10
10 min goes just to wipe the chip tho :(
But got there in the end
Good idea about cutting the old eeprom off lot easier way of soldering socket on
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Re: Offsets when burning different EPROMS

Post by j_ds_au »

vp304 wrote:Owner had a spare vs v8 chip
So i was laughing
My uv eraser took around 8 to 10
10 min goes just to wipe the chip tho :(
But got there in the end
Good idea about cutting the old eeprom off lot easier way of soldering socket on
I'd be wary of the reliability of the EPROM data if it's only marginally erased, particularly at high or low temperatures.

First ensure the quartz window is clean of gum residues with turps. If that's not the problem, and especially if it's an Intel EPROM, program all bits to 0 and then try erasing.

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Re: Offsets when burning different EPROMS

Post by vlad01 »

The higher the capacity the eprom the longer it takes to clear under UV as the cells have a physically smaller surface area for exposure.
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Re: Offsets when burning different EPROMS

Post by antus »

It depends on the eraser too. If you have a memcal and a standard blue eraser with a draw and your trying to fit the memcal in the hole with the draw out as best you can, the light doesnt enter straight and the whole chip will never erase. In this case you need to flip the chip over and expose it on the opposite side angle to get a good erase. You'll never get it all erased due to the poor angle of the UV light on the window. You might find big chunks done erase or you might find a few stubborn bits dont erase, but over baking it in the eraser isnt the best option and might never work.
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Re: Offsets when burning different EPROMS

Post by kojab »

IMG_20201109_193649.jpg
IMG_20201109_193621.jpg
Modified my blue box a few years back
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Re: Offsets when burning different EPROMS

Post by antus »

Nice design! :thumbup:
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