This is an instance of me not knowing the "why" but knowing "what works"
All of the chips with 512 in their name have been 64K chips. This was a problem back when the Radeon 9800 was king and we were fighting the 64K vs 128K battle.
Thank you for the technical details, though I have to admit I still don't know what exactly your explanation means.
I just know that is a 64K chip....
My apologies.. I get a little anal retentive about technical matters. I always want to be as accurate and precise as possible. And I could have been a little more clear. I'm going to blame a lack of Mt. Dew.
Memory structures can come in numerous configurations: the most common being 8 bit wide, 16 bit wide, and 32 bit wide "words"; and have ever increasing densities: 256 kbits, 512 kbits, 1024 kbits, etc. Memory parts are specified by this bit density, not by the word density. For example: a 512 kbit part can be 64k of 8 bit words, or 32k of 16 bit words, or even 16k of 32 bit words.... It all comes down to how the manufacture wants to configure their part internally. This is usually reflected in the part number somehow.
What set me off in your original explanation was that you stated:
It would seem that there are 8 pages of 64K each but for whatever reason, when these chips are used as EEPROMs for GPU, they only access the "first page"
This would imply that these parts have 512k words (64k times 8) internally which they do not... they have 512 kbits configured as 64k worth of 8 bit words. I know... refer to the part above where I mention "anal retentive".
On a side note: These memory parts generally have what is called a "page mode" of access. Where you send a "read (or write) page" command and the part will return an entire page worth of data which can vary in size again depending on how the manufacture wants to make the part. This is usually only possible with serial flash parts which the devices you're using here are. The particular part called out here has 256 word pages, so when you do a page read you get 256 words back. For parallel flash parts there's another meaning for "page" but we won't get into that here.
I hope this explanation is a bit clearer,
hyram
PS: I've specifically avoided the usage of the word "byte" as sometimes it can add more confusion that it resolves.