Board Circuit diagram



In the final few yrs, the to be had vary of operating systems for PCs has increased dramatically. Various free (!) operating methods were added to the record, the kind ofs BeOS, OpenBSD and Linux. These programs are additionally available in numerous colors and flavours (versions and distributions). Windows can be no lengthyer merely Windows, as a outcome of there are actually a few different versions (Windows ninety five, ninety eight, ME, NT, XP, Vista and 7). Computer users subsequently have a large variety of choices in regards to the working machine to be used. One drawback is that now not all hardware works equally smartly underneath the quite loads of operating techniques, and with reference to software, compatibility is a meanss from being universal. In other words, it’s difficult to make a just right selection.


Switching from one working system to every different - that’s a unsafe industry, isn’t it? Although this may just be somewhat of an exaggeration, the protectedst method continues to be to put in two different operating methods on the identical PC, so that you can always easily use the ‘old’ operating machine if the model new one fails to fulfill your desires (or fit your taste). A software solution is continuously used for the sort of ‘dual device’. A program known as a ‘boot supervisor’ can be utilized to permit the user to choose, during the start-up course of, which exhausting disk will be used for starting up the pc. Unfortunately, this doesn't at all times work flawlessly, and in most instances this boot manager is changed by way of the usual boot loader of the working system when a new working system is put in.

In many cases, the only remedy is to reinstall the software program. The resolution presented right here does not endure from this problem. It is a exhaustingware resolution that causes the main and secondary hard disk drives to ‘swap places’ when the computer is began up, if so desired. From the point of view of the computer (and the software operating on the computer), it appears as though these two arduous disks have actually changed locations. This trick is made possible through a feature of the IDE specification called ‘CableSelect’. Every IDE arduous disk can also be configured to make use of either Master/Slave or CableSelect. In the latter case, a signal on the IDE cable informs the exhausting disk whether it's to act as the master or slave device. For this motive, in every IDE cable one lead is interrupted between the connectors for the 2 disk drives, or the relevant pin is disregarded from the connector.


This lead tos a low degree to be current on the CS pin of one of the pressures and a excessive stage to be present on the CS pin of the different one (at the a lengthy way end of the cable). The circuit proven here is linked to the IDE bus of the motherboard via connector K1. Most of the signals are fed right away from K1 to the opposite connectors (K2 and K3). An IDE hard disk is related to K2, and a second one is connected to K3. When the computer is swaped on or reset, a pulse will seem on the RESET line of the IDE interface. This pulse clocks flip-flop IC1a, and relying on the state of change S1, the Q output will go both excessive or low. The state on the Q output is of course all the time the alternative of that on the Q output. If we expect that the change is closed all the manner in which via start-up, a low stage will most doubtless be current on D enter of IC1a, so the Q output will probably be low following the reset pulse.


This low degree on the Q output will cause transistor T1 to conduct. The present flowing through T1 will cause LED D1 to light up and transistor T2 to habits. The onerous disk attached to attachor K2 will to that end see a low level on its CS pin, with a function to cause it to behave as the grasp force and for this reason appear to the pc as the C: force. A high level will appear on the Q output following the reset pulse. This will stop T3 and T4 from habitsing, with the consequence that LED D2 will most certainly be extinguished and the laborious disk attached to attachor K3 will see a high level on its CS pin. For this disk, this means that it is to behave as a slave pressure (D: force).


If S1 is open when the reset pulse occurs, the above scenario is after all reversed, and the exhausting disk hooked up to connector K2 will act because the D: drive, whereas the laborious disk hooked up to attachor K3 will act because the C: pressure. Flip-flop IC1a is included right here to forestall the onerous disks from swapping roles right via use. This may have disastrous outcomes for the information on the exhausting disks, and it will most seemingly result in the pc to crash. This implies that you shouldn't have to fret about affecting the operation of the pc for these who alternate the swap atmosphere while the computer is running. The state of the flip-flop, and to that end the configuration of the laborious disks, can simplest be modified during a reset.

The circuit is powered from an influence connector for a three.5-inch drive. This good thing about the use of this connector is that it simply fits onto a normal 4-way header. However, it's essential to have a look at the correct polarity when attaching the connector. The purple lead should be related to pin 1. Constructing the exhausting disk selector is simple if the illustrated printed circuit board is used. You will need three IDE cables to attach the circuit. The best concept is to make use of brief cables with only two connectors, with all pins related 1:1 (no interruption within the CS line). The IDE connector on the motherboard is hooked up to K1 using one cable. A cable then runs from K2 to first exhausting disk, and any other cable runs from K3 to the 2nd laborious disk. This means that it is not possible to connect more than two laborious disks to this circuit. You must additionally be certain that the jumpers of each disk drives are configured for CableSelect. To learn how to do this, check with the person manual(s) for the pressures.