Hi, In my PC-1500 i had problems with the first TE-1507 version using Xicor memory.
It was impossible to write something in an unprotected X28HC256.
The Team1560 needs were to have a big system RAM and a place to test system ROM extensions.
Done ! The TE-1507 is now working with 2 RAM ICs and the R/W protection is done by jumper.
Here are some pictures the prototype :
This one, number 3, is reserved for…….. ? Stay tuned 😉
The release version should be available in one month.
Are these modules actually for sale? Or are the plans to make them available?
Great work – how can I purchase one?
Honestly speaking the cheapest way to implement a memory module might be, awkwardly, an STM8S003 plus an SPI flash ( STM8 works as an agent. ) The overall chip cost can be less than 2$, and with a microcontroller, the system can have a better flexibility.
Amazingly, here in China, either a 128 Mbit SPI Flash or an STM8S003 is priced less than 0.2$. I was truly astonished when I found that a microcontroller is cheaper than two 74 stuffs.
Actually, turns out Cypress has a drop-in, non-volatile, replacement for the 62256. It’s a bit expensive ($15 a piece), but otherwise it really simplifies things.
You might also look at the EverSpin MRAMs. These are magnetoresistive non-volatile RAMs (no battery needed), but with access times, enabling, and addressing that allow them to replace SRAM. The only catch is that they seem to be only in 3.3V versions.