Custom-built multi-bank Roland M-256/M-512 memory cards

[dojoe]

Hah, yeah, the 16A won't do you much good The D-50 uses 256kbit, i.e. 32kbyte, so that's A0 thru A14. Our card uses a 4mbit chip and supplies A15 thru A18 from the slide switches. Note that ordering the address bits in this way is not really necessary - you can freely rearrange address bits as you please if it simplifies PCB routing. The MRAM isn't going to care where those bytes are stored after all

The edge connector actually supports up to 19 address bits (the MR signal is used for A18 on some PCM ROM cards) and I've built jumpers onto the card that will switch A15 thru A18 between the slide switches and the edge connector, allowing any configuration between 16 banks of 256kbit and one bank of 4mbit. We only ship the 16x256 and 8x512 variants since that's the only RAM card sizes used by synths, but I have deliberately made the card hackable that way if anyone wants to dabble in custom PCM cards

[Avro_Arrow]

Thank you dojoe for all your help and insight.

I'm going to go with a static ram with battery and MXD1210 (or similar).
I'm just going to use dip switches for the extra address lines.
This way I can just stick with the 5 volt logic and not have to
convert to 3v3 data lines. I'm a wimp, I know. Its also dirt cheap.
I can live with changing the battery every five years.

Thanks again!
James

[dojoe]

I'm a wimp, I know.

But you also opt out of a buttload of headaches

Good luck with your project, let us know how it goes!

[Avro_Arrow]

I'm a wimp, I know.

But you also opt out of a buttload of headaches

Good luck with your project, let us know how it goes!

Thanks, I will!