Sidecar IT-99/4A 32k ram expension KiCad design changed

[HomeLate]

Hi Evie,

I ordered some PCB's to build the Sidecar memory expension for the TI-99/4A. I didn't notice the changes you made for the memory on the PCB. The CY62256NLL-70 listed in the BOM won't fit ofcourse. Which memory chip did you have mind while you made the design changes?

Cheers, Frank

[evietron]

It's the SNX suffix, SOP28. They are obsolete but you can get them cheap from AliExpress.

[HomeLate]

Thanks! I found and ordered these one Digikey: CY62256NLL-70ZRXIT. The pinout and other characteristics match.

[evietron]

R=Reverse, X=TSOP1 (not SOP28). You'll need a new PCB.

[HomeLate]

Crap... I noticed this too late.

[evietron]

Sorry about that, you might be able to return the item! Try CY62256NLL-55SNX or 70 or SNXI. The speed does not matter. They are about $3 each new from Mouser/DigiKey, or $5 for 10 from AliExpress.

[HomeLate]

These are both SOP28 but the KiCad project contains a TSOP1 package. The pinout of that package also don't match with any of the CY62256 TSOP1 chips.

[evietron]

Oh! I see what happened now. My production boards all used SOP28. I decided to switch to TSOP, but never ended up manufacturing them. I really apologize for the confusion. I will update the PCB to work with the part you ordered.

[HomeLate]

Thanks, that would be great! I ordered the SOP28 CY62256NL initially which was listed in the BOM. I'll return the CY62256NLL-70ZRXIT chips I ordered from Digikey.

[evietron]

OK the SOP version has been committed. It still might be helpful to add a JTAG header if you don't have an TQPF-44 socket. Let me know if you'd like me to add that.

[HomeLate]

Thank you! I'm able to program the ATF1502ASL, I have a devkit somewhere. Thanks again, the pcb is in order.

[evietron]

OK let me know how the build works out!

[HomeLate]

Hi Evie,

Received the new PCB's today, build one and it works! Thank you very much for your assistance!

Frank

[evietron]

Awesome, glad to help!