Advise needed for 32k expansion

[moije]

Hi,All

Today I finally recived this memory expansion

And i want to turn it in a non volatile mem(like minimem).

So maybe with a 3xLR3 holder(4.8v) or 4xLR3(6.4v)with 2 diodes in serial.

I also need a switch to disable 32k without loosing data in it(don't want XB to Write on it).

I wrote a prog that run from minimem and gives me the ability to store multiple files in expmem2 from expmem1(buffer).

I was wondering if someone could give me tips for soldering and how much power it will need.

Thanks in advance.

[moije]

Maybe JEDIMATT CAN HELP ME?

 

[Artoj]

Here is the info direct of  "The Brewing Academy Website"

 

It runs off of +5v, using about 5-10mah. There is one configuration jumper to either take power from an external 5.5/2.1mm tip-positive 5.0 VDC power supply, or the TI-99/4A sideport. It will work with your Speech Synthesizer installed IF you use an external power supply (available separately) OR modify your speech synthesizer to supply power at pin #1.

[moije]

Thanks Artoj,

I got the docs,

but I want to take with me the expansion(like i can with the minimem)

and switch it off without loosing what is in.

 

 

[+jedimatt42]

The power consumption is pretty low if the bus buffer and other logic chips are HCT type.

 

It has a power supply connector on the back. Instead of batteries, you could just leave it powered. When I built them there was a 3 pin header that controlled if the +5v came from the TI expansion port, or from the power supply. So you could also tap in there for battery, the center pin feeds the board, the outer 2 are the different supplies.

 

To disconnect the circuit from the bus, and to allow an alternative memory expansion, I would wire a disconnect switch to the _245's enable feed, and a 20k pull-up to the same pin. When the switch is closed, the feed can override the pull-up, the pull-up is in full control when the switch is open.

[moije]

Thanks so much Jedimatt

What do you think is better:

 3LR3 4.8v   or

 4LR3 with 2 diodes 6.4-0.6-0.6=5.2v ?

 

[+jedimatt42]

Everything I am reading says you can't rely on such simple math for voltage drop via a diode. 

 

There is also probably more power to save if you examine the SRAM datasheet.

[+jedimatt42]

You may have noticed that schematic doesn't include power to the chips.

[moije]

Ok Thanks for both attention

I was a bit nerveous about the modifications.