Jump to content
IGNORED

Suitable SRAM Replacement


Shift838

Recommended Posts

8 hours ago, F.G. Kaal said:

The interrupt is not important on the IDE card.

 

One of the first things that the INIT routine of the IDE DSR does is to disable the interrupt of the clock chip.

One of the things I noticed in the very beginning of the IDE card is that sometimes when the DSR is not loaded yet in the RAM, and thus the RTC interrupt is not disabled, that the system hangs because the RTC had generated an interrupt after power on. That is why I disconnected the interrupt pin. Al is fine after the DSR is loaded.

 

Fred if I snipped the interrupt line right here would that be the best location? Or should I do it closer to the BQ4852/42 pins? Thanks 

Ide card interrupt snip.jpg

Link to comment
Share on other sites

On 9/29/2023 at 3:46 AM, RickyDean said:

Fred if I snipped the interrupt line right here would that be the best location? Or should I do it closer to the BQ4852/42 pins? Thanks 

Ide card interrupt snip.jpg

That seems to be the correct location. Then it doesn't matter what clock chip is installed ... the interrupt is disabled for sure.

  • Like 2
Link to comment
Share on other sites

  • 5 months later...
On 9/27/2023 at 11:28 PM, RickyDean said:

       Wow, I keep resurrecting these old threads. On the IDE card, as discussed by @Swim there is the BQ4852 that has 512k Sram on board, so if you use it you don't need the 512k sram chip. It has 36 pins two of which are not connected, one that is a programmable interrupt, and then it has a separate  Microprocessor reset, apart from A18 address line.

       On the other hand I have in my procession about 20 or so Dallas DS1251Y timekeeper SRAM 512 x 8 that is 32 pins. It does not have a programmable interrupt, and the Microprocessor reset pin is shared with A18 address. It seems like I can build a small board here and use the Dallas chip in place of the BenchMarq chip. Is the interrupt important here on the IDE card?

       The 32 pin BenchMarq BQ4842Y that can be used on the IDE card doesn't share quite the same pin footprint. I think it would be easier to fit the Dallas in the 36 pin slot. The interrupt is probably used for CRU purposes according to the schematics, so could that be done another way? What do y'all think? I'm just wanting to see if I can use what I have on hand.

 

  

bq4852Y.jpg

Dallas DS1251Y.jpgimage.thumb.jpeg.9a88a45e1a694dca34682e5c43ff4118.jpeg

bq4842Y.jpg

I' wanting to purchase some of these BQ4852 Cloc/Sram chips from Rochester Electronics for the IDE cards. There is a minium purchase requirement of 250.00. Is anyone else interested in buying a couple of these IC's at $50.88 + shipping cost if any, before I make a firm decision? PM me if interested.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...