2 Megabit EPROM question

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Thenewestdev
Posts: 3
Joined: Fri Sep 27, 2019 2:14 am

2 Megabit EPROM question

Post by Thenewestdev » Sun Oct 06, 2019 8:41 am

Greetings, Thank You for your time


I have a M27C2001-12F1 IC 2 megabit / 256 Kilobytes (KB). My PRG file is 16Kilobytes am I really supposed to copy onto itself 15 times?

The chips and bin files I have are:

M27C512 EPROMs ST 512 kilobit / 64 kilobyte // PRG 64KB

M27C2001-12F1 IC 2 megabit / 256 Kilobytes (KB) // CHR 16KB

Again thank you for your time, it is appreciated.

krzysiobal
Posts: 589
Joined: Sun Jun 12, 2011 12:06 pm
Location: Poland

Re: 2 Megabit EPROM question

Post by krzysiobal » Sun Oct 06, 2019 9:03 am

Formally it depends on what you're going to do with higher, unused address lines (A14-A17). If you plan to wire all of them to GND, write it at the beginning of EPROM without repeating. If you plan to wire all of them to VCC, write it at end of EPROM. If you plan to wire them to any other combination, write it at desired offset.

But because repeating the content 15 times and writing whole memory cost you few seconds more, you SHOULD do it because later you won't risk any mitake.

Just don't left the higher address lines float. Even if whole content is repeated, non-connected address lines will cause the memory to constantly output data from new address, and because the setup time is nonzero, there will be transient states on data bus, causing data bus to be wrong.

Thenewestdev
Posts: 3
Joined: Fri Sep 27, 2019 2:14 am

Re: 2 Megabit EPROM question

Post by Thenewestdev » Sun Oct 06, 2019 9:30 am

Great explanation, I will save it in my notes.

Best regards,

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