Building a NeoRam Ram expansion memory cartridge for the C64 computer

[Zippy Zapp]

Ok, thanks for the information it is much appreciated.

[banman]

Hi Zippy Zapp,

I was just checking on the data sheet for the HM628512 SOIC RAM chips and noticed a few variants.

https://www.google.com/url?sa=t&source= ... ac4TPho6BY


There's a 'LV' low voltage and a regular version amongst others from what I can tell.

Would you happen to know what type of HM628512 SOIC RAM chips you have on your PCB? Thanks.



It seems you had much better success at the reliability of your RAM chips than I had.

I am getting more PCB boards delivered and I will order Ram chips from the links you used.
I want to see if I can achieve similar success to you.

[Zippy Zapp]

Would you happen to know what type of HM628512 SOIC RAM chips you have on your PCB? Thanks.

They are HM628512CLFP-7

It seems you had much better success at the reliability of your RAM chips than I had.

I am getting more PCB boards delivered and I will order Ram chips from the links you used.
I want to see if I can achieve similar success to you.

I only built one board. I have another with 2 RAM chips installed but haven't finished it. I am waiting for new boards to arrive that are ENIG because the ones I ordered from PCBWay were for just testing are not ENIG.

[banman]

Hi Zippy Zapp,


Great, thank you for that information.



I checked the datasheet out for the Hitachi HM628512CLFP-7 RAM chips out. I think the C means CMOS and the L & P means Low Power. I am not quite sure what the F stands for.


https://pdf1.alldatasheet.com/datasheet ... LFP-7.html

It does indeed appear to be suitable for battery backup solutions.

Eslapion mentioned a PCB manufacturer called JLCPCB. I looked at their site. The prices for standard HASL boards were very cheap compared to PCBway's. I ended up ordering 20 various PCB's for $30 AUD including delivery.

I am not sure if this was a first time customer purchase or their regular price. I will try get some HM628512CLFP-7 like you have Zippy Zapp and see if it's my awful construction skills or the those Cypress RAM chips I used were doggy.

[eslapion]

...
Eslapion mentioned a PCB manufacturer called JLCPCB. I looked at their site. The prices for standard HASL boards were very cheap compared to PCBway's. I ended up ordering 20 various PCB's for $30 AUD including delivery.

At your service!

[banman]

Hi eslapion,


I appreciate your help.

I got a message from JLCPCB 2 days ago saying that the PCB boards have been shipped.
I had them shipped economy, I imagine that they will take a few weeks to arrive.

[Zippy Zapp]

I see you get a few choices for board thickness. Was there a standard back then? I see some of my carts are not as thick as others. Epyx Fast load seems to be less than modern boards. What thickness do you typically use?

[eslapion]

I see you get a few choices for board thickness. Was there a standard back then? I see some of my carts are not as thick as others. Epyx Fast load seems to be less than modern boards. What thickness do you typically use?

Standard PCBs are 1/16" or 1.6mm. This includes PCBs for C64 cartridges.

[banman]

Hi Zippy Zapp and eslapion,


I believe I have ordered all boards with 1.6 mm thickness from JLCPCB. I will check them when they arrive.

[Zippy Zapp]

Thanks guys. @banman, did you order with beveling? Just curious if the NeoRAM has the required space at the edge.