I started with aa ben eater setup with 32Kb sram (Alliance AS6C62256-55PCN 256K, 2.7-5.5V, 55ns 32K x 8 Asynch SRAM) but only 16kb of that is mapped.

I want to experiment with 48Kb ram, 16kb rom with one page for IO using the 8-bit comparator. Should I just map one and a half of the SRAM (two ICs0 or is there a reasonable 512kbit or 1024kbit alternative to stay with one IC? For example is the Alliance AS6C1008-55PCN (LP SRAM, 1Mb, 128K x 8, 2.7 - 5.5V, 32pin PDIP, 55ns) a reasonable option?

it depends on your usecase and future projects.

for example i usually buy pretty high capacity chips (like the AS6C4008, 512kB, 55ns), so i can cover both cases where i need a lot of Memory for some project, and when i don't (ie just ground spare address lines).
that way i don't need to buy a lot of different SRAM ICs, just a lot of the same type.
same with ROMs, i've been exclusively using the ST39SF040, which are 70-55ns 512kB Flash chips. but so far i've never used the fully capacity in a 65xx, but my 68k SBC does make use of 2 of them for 1MB of Flash.

though i did have 2 small exceptions, first the IS61C5128, which is also 512kB but with a 10ns access time (and only cost half a much as the AS6C4008). they only come in a SMT package though but are a very good fit for the 65816.

and second, the W24512AK (64kB, 10-15ns) and W241024AK (128kB, 10-15ns). they are insanely fast, cheap (like ~1-3 USD), and physically smaller compared to the AS6C4008 while still using a DIP package. so i got myself a lot of those too in case i need to build something requiring high speed DIP RAM in a tight space (like my already ordered Graphics card and the new 65C02 SBC i've designed).

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in your case the AS6C1008 (128kB) costs ~4.70 USD on mouser, while the AS6C4008 (512kB) is ~6.30 USD. so personally i would just spend a bit extra for the higher capacity ones in case i might need it in a future project.
but again that's just me... if you know that you won't ever need it, then just use 2x 32kB chips or buy something that covers your usecase without being too expensive (like the 64kB or 128kB ones).

I've been using the Winbond 'skinny' W24512AK-15 (64K) chips from this vendor listing for several years in my projects without problems. That vendor also sells the W241024AK-15 (128K) version for the same price.

Both look interesting chips, but aren't carried by the usual suspects (Mouser, Digikey, LCSC) and though digipart shows a number of vendors, none are any with whom I have had previous dealings. Are AliExpress the best way to obtain them?

(Also: further investigation for SM parts - I haven't looked for a datasheet yet).

Neil

I also got mine from Ali Express (maybe even the same exact vendor) and out of the 15 I bought only 1 was dead. Pretty good for the price, though obviously your mileage may vary.

So these are NOS or pulls, then? Faintly worrying that the first review on the vendor mentioned by Michael suggests fakes...

oh, that's a good idea just to buy bigger ICs in case I have a use later. could even try banking I guess...

Used RAM are generally reliable. You can also test them on TL866II and eBay has excellent return policy, so I generally buy them used.
Bill

I ordered a bunch of these at Michael's recommendation. Have had no trouble with the vendor or with quality issues. The only thing I noticed about them is that they seem to be a bit weak - they don't seem to quite make it to CMOS voltage levels, which did give me some trouble on one noisy board. I redid the board to make it less noisy and they worked fine.

I also ordered quite a few of these: https://www.mouser.com/ProductDetail/Re ... cycode=USD which seem to be pretty bulletproof. They are in the process of being discontinued, but the suppliers seem to have had a large stock of them that they are slowly selling off.

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"The key is not to let the hardware sense any fear." - Radical Brad