Guided Tour - Third Stop: The Other Half of the Motherboard

(Now, we are looking directly down on the motherboard, on the other side of the daughterboard.)

Along the left side of this picture, we see what's on the other surface of the daughterboard. Along the right side, we see the top of the power supply. Along the bottom are ribbon cables for the floppy and hard drives. The central area is where these cables are stuffed when the case is on the computer. There are several wires coming out of the power supply, curling back and plugging into the motherboard near the top right of the picture. These supply the motherboard with power.

A 34-conductor ribbon cable connects to the motherboard near where the wires come out of the power supply. Next to this connector are two IDE connectors - the primary "PCI IDE Connector" and the secondary "ISA IDE Connector". The "PCI IDE Connector" used to be connected to the 520MB hard drive which came with the computer, but now the hard drives are connected to the GSI 2C card seen earlier in the tour.

The computer's clock chip is easily found in the center of this picture. It is a "Dallas 12887 Real Time Clock". This large black chip (with its integrated battery) keeps track of the time and date when the computer is turned off, and also stores the computer's BIOS settings. This chip, keeping with the design of the early PCs, uses only two digits for the year. At the start of the year 2000 the chip, and others like it, will correctly change these digits to 00. The chip also stores the century number, but the operating system must change it. Thus, after January 1, 2000, the year '2000' must be manually set (once is enough), in order to change the century number.

Below the clock is a 20-pin "Modem Connector or Serial Port B" connector (or the "JMOD" jumper). It was intended to be connected to certain modem cards, and the BIOS allows this to be used as a second COM port. (One standard 9-pin serial port is available on the back of the computer, top center in this picture.) Most internal serial port connectors are only 10 pins. I had to e-mail Packard Bell's technical support to find out what the pinout is - nobody I talked to locally had ever heard of a 20-pin serial connector. Someday, I might put together a cable so that I have a second 9-pin serial port available on the back of the computer.

There's a large white connector near the top of the picture, next to the daughterboard. I don't have a clue what this is - the User's Guide calls it "reserved".

At the bottom left, we can see three of the four SIMM sockets. Above the SIMMs is one of the four chips of the Intel MERCURY chipset. Running from the top left corner, along the top and toward the bottom right corner, we see the CD-ROM's audio cable.

Next, we'll move on to the drives.