Subject: Re: [stella] Cartridge PCBs have arrived From: Chris Wilkson <ecwilkso@xxxxxxx> Date: Tue, 08 May 2001 02:13:00 -0400 |
In message <0e2fft85fpsopjjivminsu35ob8ut2a0j9@xxxxxxx>, Erik Mooney writes: >On Tue, 08 May 2001 00:32:18 -0400, you wrote: > >>The board uses a 7404 Hex Inverter (14-pin DIP) to invert the address/chip >>select line. I designed the board specifically for use with 4K ROMs. 2K >>should also work, but anything larger than 4K (2732s) will not work. > >I'm no electronics whiz, but I recall someone mentioning that the inverter >for the chip-select line could be done with a single transistor, no need >for a (comparatively) bulky and expensive 14-pin DIP chip. Based on my >sketchy knowledge, I think that's correct. Anyone? Wilkson? Yah, you can do this...with a couple of resistors added. Cheaper, but only by a few cents. A 7404 chip only costs 30 cents or so. A transistor is maybe 10 cents and a resistor is 1 cent. These are rough figures of course. But the relative costs are about right. In this case, since the pcb is designed to fit a standard atari case, there's plenty of extra room for the dip. Besides: 100 14 pin dips are easier to install than 100 transistors and 200 resistors! :) Of course if you're making 100 boards, that 22 cents comes to 22 dollars! ;) Ahh....tradeoffs, tradeoffs.... -Wilkson - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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