I *highly* suggest you invest in a multimeter, instead
I want to listen your advice.
Do you think this multimeter can meet my needs :
MULTIMETER (PDIP ATMega8 version)
If you know any better one, please let me know.
infiniteneslives wrote:If you use the circuit I provided the link to eariler the diagram uses a 102 capacitor which is a 1000pF (1nF) cap a diode and 74LS74 chip.
This is great, Thanks!
Do you think this can work :
How does it work : By hijacking A19, A18, A17 the AT27C080 function as eight AT27C010 because Signals of A19, A18, A17 can produce 8 different combinations (000, 001, 010, 011, 100, 101, 110, 111) which at a time just one of them can be activated by pushing reset button so it is possible to use eight 256 KB (128PRG+128CHR) games by using this method.
I have not test it yet. I just conclude the idea by combining these two information :
NES Custom Multicart - Super Mario All-Stars
If you've read my other tutorials, you might recall my mention of a chip called a 74xx161 (xx being LS or HC, doesn't matter in this case), which was used as a basic mapper in early NES games. The 74xx161 is a 4-bit synchronous binary counter. Basically, upon each strobe of the clock pin, the binary value of the 4 output pins increases by 1. While the output counts up from 0 to 15, then starts over, if you just consider the lowest two pins, you might be able to picture how it can rotate between 4 different digital addresses.
The largest 8-bit EPROMs are 27C080 or 27C8001 EPROMs, which are 8 Mbit in size. which is equal to 1 MByte. Which means each "bank" of ROM space must be 1/4 of this, which is 256KB. 4 banks, 4 combinations of signals (00, 01, 10, 11) coming off the two pins from the binary counter, get it?
In essence, what we're doing is hijacking the two highest address pins of the EPROMs, and letting the NES only choose the lower address pins (A0-A17), so it only sees a 2Mbit ROM space at any one time.
Could you go for 8 banks by using three bits from the 4-bit counter, or 16 games using all four bits? You bet, but then you need your ROMs to be 128KB each for 8 games or 64KB or less for 16 games. The largest ROM included on this multicart will be the 256KB Super Mario Bros. 3 PRG ROM, and to keep the logic simple, this will be the size of each ROM bank.
Is this sort of mod possible for other cartridge-based systems? Probably. This project takes advantage of the fact that +5V is supplied to the cartridge at all times, even when in reset mode, and it also provides a direct link to the reset signal. I'm not sure this applies to all systems. Other systems might cut power to the cartridge, or might simply not provide any means of detecting a reset.
74LS74 used in many 2in1 Reset based carts
I want to know what is the difference between 74xx161 and 74xx74? Which one is better for my purpose? Even if there is a better choose other than these two, specially something smaller, please let me know.
What is the full part number of D(148)?