PC-Task Manual V1.04 IBM PC emulation for the Amiga range of computers Copyright 1992 by Chris Hames All Rights Reserved Worldwide Copyright PC-Task software and documentation are copyright Chris Hames. No part may be reproduced, transmitted, translated into other languages, posted to a network, or distributed by electronic or other means without the express written permission of the author Chris Hames. This software may not be rented, lent or leased. You may not decompile, dissassemble or reverse engineer the software. Disclaimer No responsibility or liability will be accepted for any damage that may appear to have resulted from use of this program. All use is at your own risk. The software is provided "as is" without any warranty implied or otherwise to the fitness or accuracy of the software and documentation. The documentation is believed to be correct but the author reserves the right to update the software and/or documentation without notice. TradeMarks Commodore is a registered trademarks of Commodore Electronics, Ltd. Amiga, Amiga 500, Amiga 2000, Amiga 3000, AmigaDOS, Amiga Kickstart, Amiga Workbench are trademarks of Commodore-Amiga, Inc. IBM, CGA and MDA are trademarks of International Business Machines Corp. MS-DOS is a registered trademark of Microsoft Inc. All other trademarks are trademarks of their relative Companies. Contents General Information Introduction 1.1 System Requirements 1.2 Backing up your PC-Task Disk 1.3 Installing PC-Task on your Hard Disk 1.4 Starting and Configuring Starting PC-Task 2.1 Option Screen and starting the Emulator 2.2 Saving options/Using defaults/Quitting 2.3 Floppy Drive options 2.4 Hard Drive options 2.5 CGA/MDA options 2.6 Parallel and Serial options 2.7 Priority options 2.8 Memory options 2.9 Emulating General Emulating info 3.1 Turning the Mouse Driver on 3.2 Quitting the Emulator 3.3 Using your PC Resetting the emulator 4.1 Getting programs to work 4.2 Using DOS 4.3 Using PC-Task DOS utils CopyToA & CopyToI 4.4 Amiga Technical Information Creating a Hard Drive partition 5.1 Creating fast temporary Drive in ram 5.2 Amiga <-> IBM file exchanging with Floppies 5.3 Amiga <-> IBM file exchanging with File Drives 5.4 Amiga <-> IBM file exchanging with Partitions 5.5 Getting as much memory as possible 5.6 IBM PC Technical Information IBM PC Boot Procedure 6.1 Other Information Technical Support 7.1 Troubleshooting 7.2 Glossary 7.3 References 7.4 1.1 Introduction Even though the Amiga range of computers are excellent, the world PC market is still dominated by IBM PC's. So you might want to run some programs written for the IBM PC but don't want to buy another computer. This is where PC-Task comes in, it allows you to run the majority of IBM PC programs on your Amiga computer and hence make use of the memory and peripherals you already have. The speed of PC-Task is directly related to the speed of you Amiga so when you make your Amiga faster your PC emulation becomes faster. Multitasking is what has set the Amiga apart from other PC's and PC-Task works fully without taking over the machine. PC-Task just becomes another application screen that you switch to when wanted. The emulator supports two floppy drives as well as two hard drives so that you have a versatile enviroment. Pseudo hard drives can be created as a file on your hard disk. This feature allows the use of already created bridgeboard pseudo hard drive files. You can also use a partition as a hard drive. The manual tries to keep things easy to understand with the more technical information that might be of use to a advanced user in later sections. 1.2 System Requirements PC-Task requires an Amiga 500, 1000, 2000, 3000 with at least 512K of ram. Versions for 68000, 68010, 68020+(and later) processors are provided on the disk. The system must be running Kickstart/Workbench 1.2 or later. 1.3 Backing up your PC-Task Disk The PC-Task disk can be copied so that should something happen to your copy you can continue to use the program by obtaining another copy from the original disk. Consult your Workbench manuals for further information on making backups. You can only make a backup for your own personal use. Please respect the enormous amount of work gone into this product and do not make illegal copies for other people. The more registered users of this product the better for you as it will promote further developement of the software. 1.4 Installing PC-Task on your Hard Disk Boot off your hard disk or a workbench disk into workbench. Then insert the PC-Task disk. You should now be looking at a workbench screen with the disk icon for PC-Task. Double click the PC-Task disk icon and a window will be displayed. In this window are various versions of PC-Task as well as a utility call TDPatch1213. Open the drawer of your hard disk where you wish to put PC-Task. Now you must drag at least one of the icons across from the PC-Task window to the drawer on your hard disk. If have a system which is running Kickstart/Workbench 1.2 or 1.3 drag the TDPatch1213 icon to your hard disk. Now you need to drag one of the PC-Task programs to your hard disk. Which one depends on which processor your machine has:- PC-Task68000 is for 68000 machines such as stock Amiga 500, 1000, 2000's. PC-Task68010 is for 68010 machines which no current amiga comes with but someone might have installed. PC-Task68020+ is for 68020 or later processors such as stock A3000's. You could of course drag all three versions across to your hard disk but this would waste some space as only one will work on your machine. 2.1 Starting PC-Task If you are running under kickstart 1.2 or 1.3 then you need to first double click the TDPatch1213 program. This program fixes bugs and adds some features to kickstart to allow reading and writing to IBM floppy disks when running PC-Task. Now you must choose the correct version of PC-Task for your machine to run. It is dependent on your processor. Here is a guide to which version is for your machine:- PC-Task68000 is for 68000 machines such as stock Amiga 500, 1000, 2000's. PC-Task68010 is for 68010 machines which no current amiga comes with but someone might have installed. PC-Task68020+ is for 68020 or later processors such as stock A3000's. To start PC-Task just double click the icon of the program that is appropriate to your machine. The program should then load up and display an option screen. If the option screen did not appear but instead a error window appeared and said you had the wrong processor then you have run the wrong version of PC-Task for you machine so try a different version. 2.2 Option Screen and starting the Emulator The option screen allows you to change various functions of the emulator but the only thing you must do to begin emulating is click the start button or press the return key. 2.3 Saving options/Using defaults/Quitting The option screen has three gadgets at the bottom right of the screen that control the configuration of PC-Task. Use Defaults - This resets all options to the default intial values. Save Configuration - This creates a file called "PC.config" which contains the configuration as currently set. PC-Task attempts to load this file each time it is executed and will use its values if found. Quit - Just quits PC-Task from the option screen. 2.4 Floppy Drive options On the botton left of the option screen are the assignments for PC-Task's floppy drives A and B. The floppy drives can be be assigned to any device and will in be used in the emulation as the PC's A and B drive. All you have to do is enter the name of the drive into the two text gadgets. By default they are assigned to DF0: for A and to DF1: for B which are the first two Amiga floppy disk drives. If you have two external floppy drives you might want to use those instead and give your default internal floppy drive DF0: a rest. In this case you would set A to DF1: and B to DF2: or visa versa. The drives by default are used as IBM PC 720K drives and hence can only read disks of that format. Please note the standard Amiga drives DO NOT read 3.5inch 1.44 Meg IBM PC disks. People who mount their drives as IBM format drives so they can read and write files using the ShareWare software MSH (see references section) or other similar pieces of software might be better using the name mounted for use with that software instead of the default DF0: etc. 2.5 Hard Drive options A Hard drive with PC-Task can either be a file on you Amiga hard disk which is treated as a hard drive in the emulator or a partition on your Amiga hard disk. You can have two hard drives with the emulator C and D. If you chose to set up only one it must be the C drive as the D drive is not available if the C drive is not found. The emulator will boot off the hard drive C if no IBM disk is found in floppy A and hard drive C is bootable. Note that some versions of IBM DOS do not work on hard drive partitions of size larger than 32 megabytes so it is suggested you create hard drives of 32 megabytes or less. If you have a existing bridgeboard hard drive file all you have to do is press the left mouse button over one of the hard drive text gadgets and enter the file name (including path) in the text gadget. If you want to create a hard drive file on your Amiga hard disk, click the left mouse button on the "Create HardDiskFile" gadget. You are then requested for the file name and size of the hard drive file. So press the left mouse button over the file name text gadget and enter the file name (including path) you wish to use. Then press the left mouse button over the size text gadget and enter the size of the hard drive you wish to create. The size is the numeric amount in megabytes it is by default set to two megabytes. If you have decided you don't want to create the file press the left mouse button on the "Cancel" gadget. To create the hard disk file press the left mouse button on the "GoDoIt". If all is well your hard drive will then start and after some seconds (depending on the size you specified and the speed of your hard drive) the file should be created. You can now press the left mouse button over one of the hard drive text gadgets and enter the file name (including path) you specified when creating the hard drive file. See the important information on setting up a partition in the technical section if you want to use a real partition on your Amiga hard drive instead of a file hard drive. It should only be attempted by advanced users. Once you have created and entered a hard drive name into the hard drive text gadget it should then come up in the startup information of the emulator. If it comes up as unavailable, something is wrong and the emulator is not finding the file or device. You must still set up the hard drive during emulation as you would on a normal IBM PC. This involves first using the DOS command FDisk and then Format (using /s option if it is to be bootable). 2.6 CGA/MDA options You can emualate two different display adaptors, MDA which is a monochrome text only adaptor that will give faster updates, and CGA which gives you color and graphics capability. You can toggle which mode you will use by pressing the left mouse button on the "Use CGA" gadget If you choose to use MDA you can set the two colors by pressing the left mouse button on one of the two color boxes. Then adjust the for red, green, and blue gadget controls on the right of them. 2.7 Parallel and Serial options You can toggle the "Use Parallel" and "Use Serial" gadgets to on or off by pressing the left mouse button above them. When the gadget appears to be down (black border above text white below) you will be able to use the parallel or serial port for printing or communications with a modem during emulation. By default both are turned on for use, if you want to use another Amiga program that uses either of these ports you might want to turn them off. 2.8 Priority options Since your machine will still be multitasking and you will want to get maximum performance out of the emulator two options are provided to control processor allocation. "Prority when selected" is the priority the processor should give to running the emulator when the emulator screen is selected. "Priority when not selected" is the priority the processor should give to running the emulator when the emulator screen is not selected. Giving a value of one for "Priority when selected" allows the emulator to get the majority of the processors time when you are working with it. Giving a value negative one for "Priority when not selected" allows other programs to get the majority of the processor when you are not working with the emulator. 2.9 Memory options In the bottom right box you will find two sets of up/down gadgets for changing the amount of memory the emulator will try to use for the IBM PC and the minimum amount it will leave free. "Memory Kilobytes" sets the amount of memory PC-Task will try to allocate for emulation with the maximum allowed being 704K. If the emulator fails to get the amount set it will try for a smaller amount until it gets too low to be functional. "Minimum Leave Available" is the minimum the emulator will leave available for other Amiga programs after allocating the main memory. This can be used to ensure that available memory does not get to low when the emulator allocates the amount it wants. Not getting enough memory for you PC, try the following:- 1. Run the LeaveSlowFast program. 2. Turn off "Use CGA". 3. Turn off "Use Parallel". 4. Lower the value of "Minimun Leave Available". 3.1 General Emulating Info The emulator starts by displaying the memory available for the IBM PC and Drive A-D's allocation. It will then try to boot off the floppy in floppy drive A. You then just have to insert a 720K DOS boot disk into the drive A which is usually the internal drive DF0:. It will try to boot off the Hard Drive C if no disk is found in A. You should now be able to run IBM PC software as you would on a real IBM PC. 3.2 Turning the Mouse Driver on To turn the mouse driver on press the LeftAmiga-P all at the same time. This should usually be done before starting the IBM program you wish to use the mouse with. 3.3 Quitting the emulator To exit out of the emulator press the LeftAmiga-RightAmiga-DEL all at the same time. 4.1 Rebooting To reboot the IBM just press the Ctrl-Alt-DEL all at the same time as you would do on a normal IBM. 4.2 Getting programs to work Some programs might work when you use the MDA instead of CGA and visa versa. Make sure the program you are trying will work on a normal IBM PC and does not require a 80386 machine. 4.3 Getting around in IBM DOS There are many versions of DOS for IBM PC's here is a quick guide to some of the most common commands. The basic idea is to type "a:" return to refer to drive a and "b:" return to refer to drive b etc. Filenames are usually of 8 characters with a 3 character ending descripting the type of file. File's ending with .exe or .com are usually programs which can be run by typing their name. Script type files .bat are text files containing a list of commands to execute which you can execute by just typing their name. General text files usually end with .doc or .txt. cls Clear the screen. date Enter/View the date. dir Show's the names/dates/sizes of files and dirs contained on a disk. dir/p Same as dir above but you press a key after each page. dir/w Same as dir but spread across the screen with just names. cd Make a directory the current(default) one, to move in and out of dirs. cd db Would go into the db directory if it was in the current dir. cd \ Take's you to the directory above(parent) the one you are currently in. type filename.??? Would display to the screen a text file called "filename.???" del filename.??? Would delete a file called "filename.???" copy filename.??? b: Would copy the file called "filename.???" to the disk in drive b. 4.4 Using CopyToA & CopyToI On the second disk that comes with PC-Task there are two IBM-DOS utility programs. They allow you to copy files between the PC-Task program and your Amiga disks. While in PC-Task you can:- CopyToI AmigaPathFile IBMPathFile To copy a file on your amiga Harddisk to your IBM floppy you could "CopyToI DH0:file.dat a:file.dat" CopyToA IBMPathFile AmigaPathFile To copy a file on your IBM floppy to your amiga Harddisk you could "CopyToA a:file.dat DH0:file.dat" 5.1 Creating a Hard Drive partition The setting up of a partition on your hard disk is a lot more complicated than using a file as a hard disk. Only advanced users should attempt this and even they must keep in mind the wrong setup could cause the loss of other data on the hard disk. You must assign a area of your hard drive for this either using software (if you have partition creating software for your hard drive) or actually create a mountlist entry for the partition in file "devs:mountlist". Here are the entries that PC-Task requires with the restrictions your entry must follow:- Device - device name of the hard drive Unit - unit number Flags - flags usually 0 Surfaces - Must have value in range of 1 to 255 BlockPerTrack - Must have value in range of 8 to 63 LowCyl - Must have value in range of 0 to 65535 HighCyl - Must have value in range of 0 to 65535 BlockSize - Must be the default 512 but is assumed. ALSO: ((HighCyl + 1) - LowCyl) Must have value in range of 1 to 1024 Note: It is recomended that you don't create partitions of over 32 megabytes. If your partition entries follow all the above rules then you don't have to worry about changing them and can skip the following. If however your partition entries violate any of the above rules then you will have to make changes so that they don't. Here is how the emulator calculates the important size and location information from the partition entries:- StartOffsetInBlocks = LowCyl * BlocksPerTrack * Surfaces SizeInBlocks = ((HighCyl + 1) - LowCyl) * Surfaces * BlocksPerTrack The way the size and start offset is calculated means that you can change values of Surfaces/BlocksPerTrack/LowCyl/HighCyl and still end up with the correct size and start offset. 5.1 Creating a Hard Drive partition (continued) Here is an example where the BlocksPerTrack is too large:- INVALID1: Device = scsi.device Unit = 6 Flags = 0 LowCyl = 1100 HighCyl = 1400 Surfaces = 1 BlocksPerTrack = 64 # This has StartOffsetInBlocks = 1100 * 1 * 64 = 70400 And has SizeInBlocks = ((1400 + 1) - 1100) * 1 * 64 = 19264 By halfing the BlocksPerTrack and doubling the number of cylinders from 301 to 602, making sure the start offset and size are same it becomes:- IBMC1: Device = scsi.device Unit = 6 Flags = 0 LowCyl = 2200 HighCyl = 2801 Surfaces = 1 BlocksPerTrack = 32 # This has StartOffsetInBlocks = 2200 * 1 * 32 = 70400 And has SizeInBlocks = ((2801 + 1) - 2200) * 1 * 32 = 19264 Here is another example where the BlocksPerTrack is too large but in this case if we double the number of cylinders we will go above the 1024 limit:- INVALID2: Device = scsi.device Unit = 6 Flags = 0 LowCyl = 1000 HighCyl = 1600 Surfaces = 1 BlocksPerTrack = 64 # This has StartOffsetInBlocks = 1000 * 1 * 64 = 6400 And has SizeInBlocks = ((1600 + 1) - 1000) * 1 * 64 = 38464 By halfing the BlocksPerTrack and doubling the surfaces we bring it within the restrictions:- IBMC2: Device = scsi.device Unit = 6 Flags = 0 LowCyl = 1000 HighCyl = 1600 Surfaces = 2 BlocksPerTrack = 32 # This has StartOffsetInBlocks = 1000 * 2 * 32 = 6400 And has SizeInBlocks = ((1600 + 1) - 1000) * 2 * 32 = 38464 5.2 Creating fast temporary Drive in ram Some IBM programs do a large amount of disk read/writing of temporary files and so you might want to set up a a drive in ram for them to use. One way is to use the Hard Drive D (or use C if you are not already). You can do this by creating a HardDiskFile in ram, then going into the emulator FDisk'ing and Format'ing it then quitting the emulator, coping the file to your hard disk and then creating a script file that copies the file to ram. So then you just have to execute that script file before running PC-Task and you will always have a fast ram drive. 5.3 Amiga <-> IBM file exchanging with Floppies MSH (see references) and similar products can be used to access files on IBM PC 720K disks from the Amiga enviroment. If you are going to use one of them specify the drive name used to access the floppy in the PC-Task option screen and you should have no trouble reading and writing from the disks while PC-Task is running as well. 5.4 Amiga <-> IBM file exchanging with File Drives MSH (see references) and similar products currently do not allow for reading of these PC-Task and bridgeboard type file drives. BUT provided on the PC-Task disk is a device called "hardfile.device" which can be used with either software to allow for reading and writing of files from file drives. Note both products currently have reservations about accessing hard drives so, proceed completely at your own risk. You must add an entry to you "devs:mounlist" and mount the device to be able to access the file drive. Also you must assign HF: to the directory containing the hard drive file. And the hard drive file must be name HardFile0 or similar depending on the unit you use. The hardfile.device automaticly gets past the partition information. This adds the complication that you loose the first track which must be accounted for in mountlist. When PC-Task creates a Hard Drive File it always uses 32 BlocksPerTrack 4 Surfaces and varies the amount of cylinders(16 per meg). But with the mountlist you must allow for that missing track. A simple way to do this is to set surfaces to 1 instead of 4 and to multipy the cylinder number by 4 and subtract one for the missing partition track. Using the way the hardfile.device calculates the drive size we can check to see we are getting the correct size for the harddrive which is the normal size minus the missing track(which is BlockPerTrack blocks). Here is how the hardfile.device calculates size of a partiton:- SizeInBlocks = ((HighCyl + 1) - LowCyl) * Surfaces * BlocksPerTrack 5.4 Amiga <-> IBM file exchanging with FileDrives (continued) Here is MSH example for a one meg hard drive file:- MH0: Device = hardfile.device Unit = 0 Flags = 0 Surfaces = 1 BlocksPerTrack = 32 LowCyl = 0 HighCyl = 62 Reserved = 0 FileSystem = L:MessyFileSystem Stacksize = 4000 Priority = 5 GlobVec = -1 DosType = 0 Buffers = 5 BufMemType = 1 # SizeInBlocks = ((62 + 1) - 0) * 1 * 32 = 2016 (which is 2048(1Meg) - 32 ) DO NOT use this device name(eg MH0:) as the hard drive specification for Hard Drive C or Hard Drive D in PC-Task. DO NOT write to the drive from in PC-Task if you have written to the drive from outside PC-Task since PC-Task was first started. IBM DOS will have buffers containing the wrong information and you could corrupt the hard drive. 5.5 Amiga <-> IBM file exchanging with Partitions MSH (see references) and similar products can read and write to IBM DOS hard disk partitions. Most products currently have reservations about accessing hard drives so, proceed completely at your own risk. This following information if provided as a guide, consult the other product documentation for a more complete explanation. The first thing to note is that you must have a different entry to the one for PC-Task as for exchanging files you must make the start block be past the IBM DOS partition information for the drive. The partition information takes up the first BlocksPerTrack blocks. Here is how a device calculates the important size and location information:- StartOffsetInBlocks = LowCyl * BlocksPerTrack * Surfaces SizeInBlocks = ((HighCyl + 1) - LowCyl) * Surfaces * BlocksPerTrack 5.5 Amiga <-> IBM file exchanging with Partitions (continued) So we take the entry created for PC-Task:- IBMC: Device = scsi.device Unit = 6 Flags = 0 LowCyl = 200 HighCyl = 801 Surfaces = 1 BlocksPerTrack = 32 # This has StartOffsetInBlocks = 200 * 1 * 32 = 6400 And has SizeInBlocks = ((801 + 1) - 200) * 1 * 32 = 19264 And since it has only one surface, to add the size of the partition information (BlocksPerTack) we only have to add one to the LowCyl. And with adding the MSH entries we get:- MF6: Device = scsi.device Unit = 6 Flags = 0 LowCyl = 201 HighCyl = 801 Surfaces = 1 BlocksPerTrack = 32 Reserved = 0 FileSystem = L:MessyFileSystem Stacksize = 4000 Priority = 5 GlobVec = -1 DosType = 0 Buffers = 5 BufMemType = 1 # This has StartOffsetInBlocks = 201 * 1 * 32 = 6432 (6400 + 32) And has SizeInBlocks = ((801 + 1) - 201) * 1 * 32 = 19232 (19264 - 32) So you can see that we have achived out goal of making the start offset go past the partition information and also subtracted the size of the partition table from the overall size of this partition. DO NOT write to the drive from in PC-Task if you have written to the drive from outside PC-Task since PC-Task was first started. IBM DOS will have buffers containing the wrong information and you could corrupt the hard drive. 5.6 Getting as much memory as possible If you have 1 meg or less memory available on your machine you might not be getting 640K for your IBM-PC emulation. You can reduce the Minimum memory to leave available as described in the Options section. If you are still short try one or more of the following:- Make a boot disk that only runs PC-Task (1.2/1.3 and TDPatch1213) Select MDA instead of CGA. Don't use Serial or Parallel. Disconnect external disk drives. 6.1 The Boot Procedure for IBM PC's When you switch on an IBM PC or start PC-Task inbuilt routines commonly called the BIOS do some intialization. Then the system checks for a HardDrive C to read from and then give control to the DOS contained on the boot disk. The the first sector on a DOS disk located on track 0 sector 1 side 0 called the boot record, is loaded in and executed. It contains a routine to read in the ROM BIOS interface for the DOS which is usually contained in a file called IBMBIO.COM or IO.SYS. Then the actual DOS program file called IBMDOS.COM or MSDOS.SYS is loaded and executed. It then loads a command interpreter called COMMAND.COM or similar which is the program you work with when typing things on the command line. 7.1 Technical Support I can be reached by the following methods, but these could change in the future:- Internet: bytey@phoenix.pub.uu.oz.au (soon bytey@phoenix.apana.org.au) FidoNet: Chris Hames at 3:633/353 Voice & Fax: +61 3 802 8513 ((03) 802 8513 in Australia) 7.2 Trouble shooting Disk-Full requester when selecting CreateHardDiskFile:- You have tried to create a file larger than the space available on the hard drive you specified. Either reduce the size of the hard drive file and try again or give a filename with a path to a different hard drive. PC-Task68020+ hangs with GVP board:- Some old GVP 68030 Accelerator Boards have a PAL (a type of computer chip) that will will not allow the reading/writing from odd locations. If you find that the PC-Task68020+ version crashes or hangs soon after the emulation starts this could be the problem. These people should contact GVP for a replacement PAL which fixes this problem. Wrong program for your processor:- You have tried to run the incorrect version of PC-Task for your processor. Try another version. Error opening or using parallel.device:- PC-Task cannot allocate the parallel.device for use. Possibly caused by another program using the printer or no parallel.device found in your "devs:" directory. Error opening or using misc.resource:- PC-Task cannot allocate the serial port for use. Possibly caused by another program using the serial port. Error opening or using ciab.resource:- PC-Task cannot allocate the timer required for use. Possibly caused by another program using timers, so try again after quitting from other programs. Keyboard seems to miss keys or similar:- I suggest users delete the keyb entry from their AutoExec.bat entry unless you really need it to remap to a german keyboard or similar. 7.3 References MSH "MESSYDOS FILE SYSTEM HANDLER" copyright by Olaf 'Rhialto' Seibert. Is a freely distributable piece of software that is available on the Fred Fish disk library collection. It allows you to read and write IBM PC 720K floppy disks as well as possibly hard disks from the Amiga enviroment as if they where just Amiga format disks. It is a shareware product so if you get and use this software please reward its author. Fred Fish Library Is a group of disks containing Freely Redistributable Software. Disks can be obtained through Amiga User Groups and dealers. 7.4 Glossary PATH The description of where a file is located. Can contain device and directory names. An example is "DF0:hello" is the direcectory path to the directory "hello" on the default internal floppy disk drive "DF0:". So if you wanted to refer to a file called "world" in that directory you would give the full filename (including path) of "DF0:hello/world". DOUBLE-CLICK Two quick presses of the button. DRAWER Directory. Allows files to be stored in a tree like structure. GADGET A graphical representation for a function that can be used using the mouse. PROCESSOR The main CPU (central processing unit) that the computer executes instructions on. The Amiga range of computers is based on the 68000 and later processors. PARTITION Subsection of a hard disk usually treated as if a seperate hard drive.