4 ms·

Not off topic but a bit tangentially... How difficult would be emulating an old SRAM chip with an RP2040 or an RP2350? It's an early 80s (or older) 2048 word,

Not off topic but a bit tangentially... How difficult would be emulating an old SRAM chip with an RP2040 or an RP2350? It's an early 80s (or older) 2048 word, 200ns access time CMOS SRAM that is used to save presets on an old Casio synth. It's not a continuous memory read, it just reads when loading the preset to memory. I feel like PIO would be perfect for that.

dmitrygr 2y ago
I did that, not just SRAM but also ROM, to fool a MC68EZ328 successfully. It works well. PIO + DMA does it well. Specifically i replaced rom & ram in an old Palm Pilot with an RP2040: https://photos.app.goo.gl/KabVe5CrfckqnFEt7 https://photos.app.goo.gl/KabVe5CrfckqnFEt7 https://photos.app.goo.gl/LGAkp6HoYAJc3Uft7 https://photos.app.goo.gl/LGAkp6HoYAJc3Uft7 Edit: I did not yet update the rePalm article but much about that is in the Palm discord. https://discord.gg/qs8wQ4Bf https://discord.gg/qs8wQ4Bf see #repalm-project channel
- tecleandor 2y ago
  Ooooh, that looks cool and the PCB seems simple (at least from this side). Congrats! Do you have anything published?
- alfanick 2y ago
  Pokemon are nice touch here
HeyLaughingBoy 2y ago
If it's not an academic question and you have an actual need for the SRAM, what's the p/n? I have some old parts stock and may have what you need.
- tecleandor 2y ago
  Oh! Thanks! I wanted to do a clone or two of said cartridges, that use, IIRC (I'm not in my workshop right now) a couple Hitachi HM6116FP each. I've also seen some clones from back in the day using a CXK5864PN-15L, that's 8 kilowords, and getting 4 switchable "memory banks" out of it...
  - HeyLaughingBoy 2y ago
    Thought I had more than this, but it's been literally decades... I found (1) HM6116, (4) HM65256's (1) HM6264 and wonder of wonders, a Dallas battery-backed DS1220, although after 20+ years the battery is certainly dead. All in DIP packages of course. And a couple of 2114's with a 1980 date code! that I think are DRAM's. If any of this is useful to you, PM me an address and I'll pop them in the mail.
bogantech 2y ago
For that you could just some FRAM with minimal effort https://www.mouser.com/ProductDetail/877-FM16W08-SG https://www.mouser.com/ProductDetail/877-FM16W08-SG

dmitrygr 2y ago

I did that, not just SRAM but also ROM, to fool a MC68EZ328 successfully. It works well. PIO + DMA does it well. Specifically i replaced rom & ram in an old Palm Pilot with an RP2040: https://photos.app.goo.gl/KabVe5CrfckqnFEt7 https://photos.app.goo.gl/KabVe5CrfckqnFEt7 https://photos.app.goo.gl/LGAkp6HoYAJc3Uft7 https://photos.app.goo.gl/LGAkp6HoYAJc3Uft7 Edit: I did not yet update the rePalm article but much about that is in the Palm discord. https://discord.gg/qs8wQ4Bf https://discord.gg/qs8wQ4Bf see #repalm-project channel

tecleandor 2y ago
Ooooh, that looks cool and the PCB seems simple (at least from this side). Congrats! Do you have anything published?
alfanick 2y ago
Pokemon are nice touch here

HeyLaughingBoy 2y ago

If it's not an academic question and you have an actual need for the SRAM, what's the p/n? I have some old parts stock and may have what you need.

tecleandor 2y ago
Oh! Thanks! I wanted to do a clone or two of said cartridges, that use, IIRC (I'm not in my workshop right now) a couple Hitachi HM6116FP each. I've also seen some clones from back in the day using a CXK5864PN-15L, that's 8 kilowords, and getting 4 switchable "memory banks" out of it...
- HeyLaughingBoy 2y ago
  Thought I had more than this, but it's been literally decades... I found (1) HM6116, (4) HM65256's (1) HM6264 and wonder of wonders, a Dallas battery-backed DS1220, although after 20+ years the battery is certainly dead. All in DIP packages of course. And a couple of 2114's with a 1980 date code! that I think are DRAM's. If any of this is useful to you, PM me an address and I'll pop them in the mail.

bogantech 2y ago

For that you could just some FRAM with minimal effort https://www.mouser.com/ProductDetail/877-FM16W08-SG https://www.mouser.com/ProductDetail/877-FM16W08-SG