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TECHNICAL A64 AND MULTITASKING A64 is fully multitasking compatible. A64 should work just fine with any program that follows the rules of multitasking programming on the Amiga. The only programs that A64 may not work with are programs that take over some part of, or all of, your Amiga, like some games and some other emulators. Which brings us to our next point. A64 can not multitask itself. Even though A64 is capable of multitasking it still takes over system resources that can not be shared with other programs, so one copy of A64 can not share these resources with another copy of A64 (See A64'S THREE MODES OF OPERATION in the SYSTEM MENU section). A64 AND MEMORY A64 is a very memory hungry program and in its full capacity it can easily use over 500k of your Amiga's memory. We recommend having a minimum of 1mb of RAM to use A64. Different memory configurations can make a dramatic difference in the speed of A64. The worst case is running A64 on a A500 or A2000 with 1mb RAM and the best case is running A64 on a 68030 based system with 32 bit RAM. On a 68030 based system speeds of over 200% have been reached with some programs. We recommend at least 1mb of RAM no matter how your Amiga is configured and this statement can be elaborated. If you are running A64 on an Amiga 1000 we recommend at least 1mb of RAM. If you are running A64 on an A500 or A2000 we recommend at least 1.5mb. The reason for this difference is not because A64 will not run on A500s or A2000s with only 1mb, it's because A64 will run faster if these machines have more than 1mb. This is because A500's and A2000's with only 1mb do not have what is called FAST RAM. This is RAM that can not be used by graphics and as a result programs run faster when using it. We also recommend running the program "FastMemFirst," found in the System drawer of the V1.3 WorkBench, before running A64. This program will force A64 (and other programs) to use this FASTer memory first. 680x0 SUPPORT All of the programs in The A64 Package will work with any 680x0 microprocessor. They have been tested with the 68000, 68010, 68020 and 68030 microprocessors. 6-1 A64 AND THE A3000 A64 V2.0 will run on the A3000, but because of the speed of the A3000, communications with C64 devices using our interface will not work. This problem also exists with all of The A64 Packages utilities that use our hardware interface. We are working on correcting this problem and hopefully it will be fixed for a future release. Please note that this problem does not exist with other Amiga models using 68030 boards, this problem is specific to the A3000. ROMS WHAT IS ROM ROM is short for "READ ONLY MEMORY." A ROM is a computer chip that is capable of storing a program and like its name implies, it is READ ONLY, which means you can not change the program it contains. ROM unlike RAM (your computer's memory) does not loose its contents when your computer is turned off. Computers usually come with ROM to tell it what to do when it's turned on. Your Amiga uses a ROM called "KickStart." THE C64'S ROMS The C64 has two ROMs that contain its operating system. One ROM holds the C64's BASIC and the other ROM holds the C64's KERNAL. A64 does not come with the C64's BASIC or KERNAL, because they are copyrighted. Before you start worrying that A64 will not work without them, this is NOT the case. A64 contains a very complex C64 ROM emulation which allows A64 to run most C64 programs, without the C64's ROMs. A64'S ROMS NOTE: This section of the manual gets a little technical by discussing machine language. If you are not familiar with machine language you should still read this section and and try to follow it as best you can, it contains some very important information about A64. As mentioned above, A64 comes with a very complex C64 ROM emulation, this ROM emulation will handle the majority of C64 programs, but not all of them. To explain what A64's ROM emulation will and will not handle we need to discuss machine language. The C64's ROMs contain machine language programs. Machine language programs are made up of opcodes. Opcodes are machine language instructions that tell the computer to perform some tiny 6-2 operation, like move a value from one place to another or perform some kind of operation to a value. It takes many, many opcodes to perform even the simplest operations on your computer. The C64's ROMs contain many thousands of these opcodes. The C64's ROMs are located in the C64's memory map at 40960-49151 (BASIC) and 57344-65535 (KERNAL), these numbers are called addresses. To access the C64's ROMs and the opcodes they contain you need to JUMP to one of these addresses. With BASIC this done with the command "SYS." For example, to reset the C64 (or A64), you can type the following: SYS 64738 [RETURN] This will cause the C64 (or A64) to enter the KERNAL ROM at address 64738 and start executing machine language opcodes starting at that address. If you were to disassemble (a disassembler is a program that turns machine language into a readable form) one of the C64's ROMs, you would get a listing similar to this: 40960 LDX #10 40962 LDA #138 40964 STA 1024 40967 ... NOTE: This listing is only used as an example and is not part of the C64's ROMs. The listing shows ROM addresses followed by the opcode stored at each address. Please note that the addresses are not perfectly consecutive, this is because different opcodes have different lengths. If A64 was to JUMP into the ROMs, using the above example, it would handle JUMPING in at all of the shown addresses: 40960, 40962, 40964 and 40967. The problem occurs if A64 tried to JUMP in at one of the addresses not shown, the addresses between opcodes. Because of the way machine language is, it is possible for an opcode to have another opcode contained within it. For example, if you disassembled the same code as above, but started at address 40963, you would get a listing like this: 40963 TXA 40964 STA 1024 40967 ... The opcode "TXA" at address 40963 is contained within the opcode "LDA #138" at address 40962. This is what A64 will not handle, when emulating the C64's ROMs, the JUMPING into the ROMs between 6-3 opcodes. If you are running a program that tries to JUMP into the C64's ROMs between opcodes A64 will trap it and display an error requester telling you "PROGRAM EXECUTING DATA ROMS." This problem is only apparent when JUMPING into the C64's ROMs between opcodes and is not a problem when running C64 programs that use the same technique to JUMP within themselves. This problem can be corrected by installing the C64's ROMs into A64. INSTALLING THE C64 ROMS NOTE: If you have an original copy of GO-64! V2.0 you can install the C64 ROMs directly from the GO-64! disk. See the GrabGO64ROMs utility in the UTILITIES section. Installing the C64's ROMs into A64, basically involves saving the contents of the C64's ROMs (this must be done on a C64) to a C64 disk and then copying them to your A64 disk. Installing the C64's ROMs into A64 is not difficult, but it does require a few small steps to accomplish. Once the C64's ROMs are installed you never have to worry about them again. A64 will automatically load the C64's ROMs and use them whenever the above mentioned problem occurs. To install the C64 ROMs you need the following: A C64 A C64 disk drive (i.e., 1541) A64's hardware interface A 5 1/4" disk, formatted on a C64, with at least 20k free NOTE: You can format the C64 disk with the utility 64Cmd from 64Tools. and the following programs that are included with The A64 Package: SaveROMs 64Tools The following procedure outlines the installation of the C64 ROMs. Part of it has to be done on a C64 and the rest must be done on the Amiga. This example assumes you are using an A64 WorkBench disk as described in the GETTING STARTED section. The first thing you need to do is copy the C64 program "saveroms" from the A64 disk to a C64 disk. This program is used to save the Commodore 64's ROMs to a C64 disk. 1. Install A64's hardware interface and connect a C64 disk drive to it (See INSTALLING A64'S HARDWARE INTERFACE in the GETTING STARTED section). 6-4 2. Run the 64Tools program found in the A64Utilities drawer on your A64 WorkBench. 3. Select the AmigaTo64 gadget. A requester will open asking you enter the source filename and destination filename. For the source filename type "A64:64Prgs/saveroms." Note that saveroms is in all lowercase characters. You do not need to enter a destination name, the name "saveroms" will be used for the destination name. After you are done entering the name select the OK gadget. The C64 program "saveroms" will then be copied to the C64 disk. Now that the C64 program "saveroms" is on the C64 disk you need to load and run it on a C64: 1. Either unplug the C64 disk drive from the interface or use another C64 disk drive and connect it to a C64. 2. With the C64 disk containing the program "saveroms" in the C64 disk drive type the following on the C64: LOAD "SAVEROMS",8 [RETURN] 3. After the program is done loading type: RUN [RETURN] 4. You will then be prompted to insert a disk into drive 8 and press any key when ready. 5. After pressing any key the C64 ROMs will be saved to the C64 disk. Now that the C64's ROMs are saved to a C64 disk you need to transfer them to your disk containing A64. 1. If you need to reconnect the C64 disk drive to your Amiga with A64's hardware interface, do so. 2. Now select the New Disk gadget in 64Tools. 3. The directory of the 64 disk will then be read. 4. Select the Exclude All gadget to unselect all the files. 5. Select the programs "basic.rom" and "kernal.rom" by clicking the left mouse button on their names. 6. At the bottom of the 64Tools window is the Destination gadget. Select this gadget and enter the following: 64:TheA64Package. 7. When you are done select the START gadget to copy the ROMs. 8. After the ROMs are copied you need to run the program StripLoadAddr on them. Select the StripLoadAddr gadget. A requester will appear asking you to enter the filename. For the first ROM enter: "64:TheA64Package/BASIC.rom." And select the OK gadget. When StripLoadAddr is done, 6-5 repeat the procedure for the second ROM. Enter: "64:TheA64Package/KERNAL.rom" and then select the OK gadget. The C64's ROMs are now installed. A64 will automatically load and use them when needed. NOTES: Once you have installed the C64 ROMs you will be able to disable A64 ROM emulation at will with the A64 ROMs menu option in A64 Prefs. Disabling A64's ROM emulation will free about 180k of RAM, but will result in some programs running slower. It is highly recommended that you install the C64's ROMs if you have access to a C64. We have come across a few programs that won't run without the ROMs installed for reasons other than the in-between opcode problem described above. You have to expect the lack of ROMs in the C64 memory map to create problems with some C64 programs. The C64's ROMs take up about 20% of the C64's total memory map, that's a big chunk of missing information. 6-6