The following is an article that originally appeared in the October '95 issue of the 'Double-Click' newsletter. The article may be freely distributed by other Commodore clubs or on Commodore related BBS systems without any further permission.
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@THE RAMLINK AND GEOS
@by Maurice Randall
The Lansing Area Commodore Club
The engineers must have been thinking ahead when they designed the original 64. They added external ports to the design that would give plug in devices access to the internals of the computer. Did they really envision the capabilities that they were providing? When you get right down to it, the 64 in it's original form is a very good basic computer and will do much of what most people need in it's stock form. I still think that a home-based computer, no matter what brand it is or how powerful it is, is mostly used for wordprocessing. Home computers have killed the typewriter business. A 64 can generate any kind of letter that anybody would need to create. The 64 has all the power anybody needs for this very popular task.
But the real power of the 64 or 128 comes when you start attaching external devices, also known as peripherals, to it. With the right peripherals, these machines will really come to life. Perhaps the most remarkable peripheral of all time is the RamLink which is designed and manufactured by Creative Micro Designs. Once you've got one of these connected to your computer, you won't know how you got along without it.
GEOS users can really make use of the RamLink, but there seems to be some confusion if the operation of the unit is not fully understood. Those that have trouble understanding it have had problems. In most cases, those problems stem from how you set up the RamLink and how you configure it. I hope to clear up some of that confusion with this article.
Remember RAMDOS? Maybe you still use it from time to time. In GEOS you won't use it, only outside of GEOS. RAMDOS was a software routine that was written by Fred Bowen at Commodore. Once you loaded RAMDOS into your computer, you could make your 17xx series REU act like a disk drive. You could store files on it and have very fast access to them. The only problem is that some programs would overwrite the area where the RAMDOS was stored in memory. Something else was needed. We needed some way to properly link our REU with the computer and have a built in DOS for controlling it. That was the original plan behind the RamLink. The RamLink would plug into the computer at the cartridge port and the REU would plug into the RamLink. The RamLink has it's own software built-in for accessing the REU so that the entire memory of the computer is freed up. Before getting close to RamLink's release, CMD designed the unit where it could also have additional memory added inside the RamLink. So it became more than just a simple interface for your REU. With it's own internal ram, it became a high-speed plug-in disk drive emulator. It could have internal ram and/or an REU plugged in for external ram. As far as the computer is concerned, both types of ram are seen as one. As the user, this fact is important for you to remember when it comes time to setting up your RamLink.
er. Remember, it is being accessed as a ram device in GEOS, not a DOS device.
If your RamLink is setup differently from this example, you can still use pretty much the
If you are thinking about purchasing a RamLink, I would highly recommend to buy one with at least 1 meg of internal ram. It is not wise to use a RamLink without internal ram. Even though you have a 1750 REU that you can plug into it, you will want your RamLink to have it's own internal ram. Keep reading and you will learn why.
Like I said, it is important for you to understand how the RamLink uses it's memory. Physically, there are many different ways that you can set up the RamLink. And then, software wise, there are many ways you can configure your physical setup.
Internally, the RamLink can have anywhere from 1 meg to 16 megs of ram. It can also have zero ram inside, but I won't even bother to discuss that setup here because I don't recommend it. I still haven't told you why. Externally, the RamLink can have memory plugged into it's rear port which is also called the ram port. Any memory that is plugged into the ram port will be used by RamLink's operating system. If the memory is plugged into the front port, the RamLink will ignore it for it's own use, but the computer will still have access to it as though it was plugged in without the RamLink.
With the external ram plugged into the ram port, the RamLink will add the amount of ram there to whatever is contained on the RamCard inside the RamLink. You could plug in a 1750 which would add 512K of ram. Or if the 1750 was expanded to 1 or 2 megs, then that amount will be added. Maybe you've got a geoRam. The RamLink can use that instead of a 1750. Even the BBGRam can be plugged into the ram port. The RamLink is compatible with any of these devices.
Once you've got the RamLink physically setup with the ram that is going to be used, it is time to configure that memory the way you need to use it. When you first power up the RamLink, it will recognize that it has not yet been configured and will set up it's own default configuration. This is good, because it allows the RamLink to be used immediately, although it most likely is not the way us GEOS users need it to be. Let's see if we can get this thing set up the way it will work best for us.
The RamLink is a CMD partitionable device much like CMD's hard drive. You can set up partitions that will make it emulate a 1541, 1571, or a 1581. You can also set up a CMD Native partition. A native partition can be anywhere from 256 blocks on up to 16 megs. It all depends on how much ram you have. Or with the emulation partitions, you can have as many of them as memory will allow. A 1581 partition requires 800K of ram, so a 1 meg RamLink can have one of these. If you want 1541 partitions, you can fit 5 of them into a 1 meg RamLink. For GEOS, we are only interested in 1581 partitions. We might as well use the 1581 partitions since they are bigger and will hold more applications. Besides there is not a suitable 1541 or 1571 RamLink driver available. There are native partition drivers available, but they have not yet been perfected. It is safest to stick with 1581 partitions.
Let's use a very popular setup with this first example: A RamLink with 1 meg of internal ram and a 512K 1750 plugged into the ram port. That gives us a total of 1.5 megs. That's not enough for two 1581 partitions. So how can we best use the available ram? First of all, load up RamTools that is on the disk that was supplied with your RamLink. Use it to delete the default partitions that the RamLink set up itself.
The GEOS operating system needs the first 64K of ram for itself. The first partition that we create will include the first 64K of ram in the system. When you use RamTools, you will be working with ram in the form of blocks. Each block is 256 bytes in size, and 256 blocks will make up 64K. So, since GEOS needs the first 64K, we need our very first partition to be something that we will not use for anything else. The type of partition to use here is a DACC (or foreign) partition. A partition of this type must be accessed directly by software. We cannot use it as though it were a disk drive, but that is ok because GEOS would just trash anything that we put there anyway. Some GEOS applications also use a portion of a ram device to store data while operating. They will usually take the second 64K if it is not being used by a ramdisk driver. So, in order to be able to use these types of applications, let's make that first DACC partition 128K (512 blocks) in size, it doesn't really need to be any larger. If you think I'm getting technical, hang on 'cause I'm going to get more technical.
The RamLink us
The RamLink uses whatever ram is plugged into the ram port first. That means that the 128K DACC partition that we just created is contained within the first part of the 1750. We want to create a 1581 partition now. We need 800K, or 3200 blocks for it. There is 384K remaining in the 1750. If we make our 1581 partition next, it is going to be partly in the 1750 and partly in the internal ram. It is not a good idea to have a partition overlap the two ram areas. So, let's fill the rest of the 1750 with a native partition. We will use that partition for whatever we might need outside of GEOS. This native partition will be 384K which in RamTools is 1536 blocks. This will be your second partition.
Now you are ready to make your 1581 GEOS partition. After making this partition, you will still have a little bit of room left in your RamLink. Just make what's left into a native partition.
If you use a program outside of GEOS that makes use of the 1750, it will most likely corrupt that 384K native partition that we created. For that reason, you should only use that partition for temporary stuff. Or make sure that you always keep backups of whatever is in that partition. When it gets corrupted, it is a simple matter to issue a format command to restore the partition. You do not need to reload RamTools to fix it. A quick format will do it, but it will be empty with no files on it anymore, hence the need for a backup.
This same problem with corrupting the native partition is the reason why we need to have some internal memory in the RamLink. The information about how our partitions are setup is stored within partition #0, the system partition. The RamLink positions this partition at the highest point in it's memory. Since the internal memory is seen last, it will be at the end of the internal memory. If we only had a 1750 and no internal memory, it would be at the end of the 1750's ram. A program outside of GEOS that uses the 1750 would most likely corrupt the system partition and we would be forced to completely reconfigure the RamLink each time we finish using that program. If the 1750 has been expanded to 1 or 2 megs, then the problem is not as likely to occur. It all depends on the program that is using the 1750.
To use GEOS with the RamLink configured this way, we will need to replace our original CONFIGURE application on our boot disk with the CONFIG RL that was supplied with the RamLink. CONFIG RL will recognize that first 64K for GEOS use if the RamLink contains nothing but internal ram or if the NORMAL/DIRECT switch is left in the NORMAL position if a 1750 or other REU is in use. The standard CONFIGURE needs to have the switch in the DIRECT position in order to see the 1750 directly. But it was not designed to recognize the 1581 partition that is inside the RamLink. So, CONFIG RL must be used and the switch put in the NORMAL position for our example here.
Another thing you must know is that CONFIG RL accesses the RamLink's ram using direct access routines. It does not use the RL-DOS routines to access the 1581 partition. The reason for this is because the RAM1581 driver that is being used is a modified version of the original RAM1581 driver that was written for an expanded 1750. It accesses ram directly. However, the RL-DOS can still be accessed using it's device number. While GEOS is running, if you do any drive position swapping, device numbers will be accessed. If the RamLink is configured as device 8, 9, 10, or 11, there will surely be a conflict with another device as the swap occurs. For this reason, the RamLink's device number must be 12 or higher. Remember, it is being accessed as a ram device in GEOS, not a DOS device.
If your RamLink is setup differently from this example, you can still use pretty much the same setup method. Maybe you only have internal ram with no 1750. You still need the 64K or 128K DACC partition first. After that, you can make your first 1581 partition. Remember, we made a native partition only to finish filling up the 1750. Just keep in mind that the plug-in ram is always seen first by the system and the internal ram is last and don't allow a partition to overlap the two ram areas.
Careful planning will provide you with a RamLink that you cannot do without.
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