Subject: Re: [stella] SRAM cart for 2600? From: Sark <ian.primus@xxxxxxx> Date: Tue, 22 May 2001 17:52:27 -0500 |
I went and bought parts, but I didn't know what voltage the battery should be. Would a 3.5v lithium computer battery do? Ian Primus ian.primus@xxxxxxx Maximiliam Luppe wrote: > > Thanks for all your help! Have you built this project? How well did it > work? > > You are welcome. I didn't build this project, but I can tell you how it > works. When you place the SRAM Cart in the Base (BASE.PCX circuit), it's > powered by the +5V line. So you can transfer the data (.BIN ROM file) to the > SRAM Cart. When you remove the SRAM Cart from the Base, the SRAM still > retain the data because it will stay in stand-by mode, thanks to the Batt. > > The Cart Connector Pin 12 is tied to ground in the VCS, but it's used to > write enable the SRAM in the Base. > > > I took a Pac Man apart, and desoldered the ROM chip. I dug through my bin > of > > scavenged chips, and found some SRAM's They are UM61256AK-15's. I checked > on > > the 'net, and they are 32k*8 SRAM chips. Will the larger chips work as > 8k*8 > > chips? > > Yes, but you'll have to make some modifications in the circuit. See the > following circuit: > > Cart +---+--+---+ > Con.----1A |1 +--+ 14| VCC > Pin 6 /1Y |2 13| 6A > (A12) 2A |3 12| /6Y > /2Y |4 7414 11| 5A > 3A |5 10| /5Y > /3Y |6 9| 4A > GND |7 8| /4Y > +----------+ > > +-----+--+-----+ > .----A14 |1 +--+ 28| VCC > | A12 |2 27| /WE > | A7 |3 26| A13----. > | A6 |4 25| A8 | > | A5 |5 24| A9 --- > | A4 |6 23| A11 - > | A3 |7 61256 22| /OE > | A2 |8 21| A10 > | A1 |9 20| /CE > | A0 |10 19| D7 > | D0 |11 18| D6 > | D1 |12 17| D5 > | D2 |13 16| D4 > '--,-GND |14 15| D3 > | +--------------+ > --- > - > The modifications are: > SRAM pin 1 (old N.C.) must be tied to ground > SRAM pin 26 (old CS2) must be tied to ground and the connection to Cart > Connector Pin 6 (A12) must be removed > 74HC14 pin 1 must be connected to Cart Connector Pin 6. The resistor and > the +5V connection must be removed. > The rest remains equal. > > > Thanks! > > > > Ian Primus > > ian.primus@xxxxxxx > > > > Maximiliam Luppe wrote: > > > > > I lost the instructions about programming. The first three chips in the > > - > Archives (includes files) at http://www.biglist.com/lists/stella/archives/ > Unsub & more at http://www.biglist.com/lists/stella/ - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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