I have started work on a new project of mine of building a simple 8-bit computer. Everything I have put together (clock, registers) has worked so far, until I needed to build RAM. For reference I have been using this site.
First, I'm using the 74LS189AN as a 64-bit random access memory, and I will use two of them to make a total of 16 bytes in my machine. I have hooked up one of the chips with the required 5V power supply and had the address data pins connected to ground along with the four digital inputs. The four outputs were connected to a hex inverter (74LS04) since the output on the 74LS189AN is inverted.
Then, the outputs of the 74LS04 are connected to four LEDs which connect to ground. The last few pins are the select and read/write pins. I connected the select to ground and the R/W pin to either high or low but had it set to low at the moment.
My problem is when I power on the chip as soon as I remove the R/W wire to Low then back to high the LEDs just keep on HIGH even though the digital inputs are LOW. After a few minutes, the chip itself begins to heat up so badly that it burns at the touch. What could be the problem; defective chip or am I reading the pin-out wrong?