mrios@ihlpg.UUCP (02/15/87)
(Line-Eater (c)1987 - AT&T Lab Bellratories) To all C64 users in NetLand: I am the Questions and Answers chairman for a local Commodore group (Computers West, in Glen Ellyn), and I was hoping that I could call upon the collective knowledge of the net to help me answer some questions periodically for the group. Here is the latest batch of questions: 1. What is the best color monitor for use with the 128? 2. Please explain what a RAM disk is and how it works. 3. Would it be possible to write a program to convert 64 programs to 128 programs? Have you heard of anyone who has done this? 4. I cannot load "Print Shop" with Micro World-302 and Epson Mx-80. Can you give me the switch combination on the interface and printer? 5. In the game "Ultima IV", where do you find the shepherd to add to the party? 6. Are there any known problems with the Okimate 10 printer? 7. Can anyone recommend a prep disk for the SAT's? 8. " " " an algebra teacher (grade 9)? And of course, the perennial question: 9. Can you help me with maintenance on my (C64/C128/1541)? This covers repeating and non-working keys, misaligned drives, and bad chips. ANY information or pointers to sources of information I get to this would be greatly appreciated. Thanx. -- Michael Rios ihnp4!ihlpg!mrios "One-nothing. Your move. Come and get me." -Rorschach, _Watchmen_
hedley@cbmvax.UUCP (02/16/87)
In article <2852@ihlpg.UUCP> mrios@ihlpg.UUCP (Michael Rios) writes: > >2. Please explain what a RAM disk is and how it works. > The term RAMdisk is often misused, and has many different meanings. Within the context of the C128/C64 machines, there are about two. Often the 1700/1750 Ram Expansion Units are reffered to as "RAMdisks". This is not really true. They are, as the name implies, devices which simply make more memory available to the system. The method through which this is accomplished is a DMA device which must be instructed by the system to transfer data between the RAM in the C64/C128 and the expansion memory. A ramdisk is a generally a software device which emulates a physical disk drive. This has the advantage that ramdisk operation is much faster than normal disk drive, so you don't have to spend so much time waiting and waiting and waiting........ Because the C64 has so much software written for it which does NOT expect a RAMdisk, it is impossible to write a 100% compatible disk for it. Even if you could, the disk size would have to be small in order to leave enough memory for applications programs. 64K is not alot of memory. The 1750 can be used to add the actual memory to the C64. In the 1750 box is a diskette which contains a software RAMdisk allowing the 1750 to act as another disk drive ( unit 10 for example ). This RAMDOS is DOS level compatible with the 1541/1571 DOSes. This means you can open and close files, get directories, and all that stuff, but commands such as BLOCK-ALLOCATE,BLOCK-READ,BLOCK-WRITE,MEMORY_WRITE, etc will not work. Everything possible has been done to make the 1750 RAMDOS compatible with exsisting software, however, 100% is not the number. ( I really don't know exactly what the number is.. ) There are other ramdisk implemenations. Forexample, the paperback seris of software packages, and GEOS both use the 1750 as a RAMdisk allow greater speed and productivity from those packages. All things written here about the 1750 are generally mappable to the 1700 REU ( for the C128 ). Note that early versions of the 1700 did not have the C128 version of the RAMdos on their demo diskettes. That softwarre may be copied, so if you have a 1700, perhaps somebody in your user group will allow you to copy their diskette. As for how it works, basically the RAMdos is installed by the user running the RAMdisk install program which redirects the system vectors on page 3 of the memory map. This wedged software then intercepts calls to the normal disk drives and either passes it on to external serial buss devices, or passes it to the RAMdos. In order to work, one page of C64/C128 memory must be allocated to the RAMdos, and the vectors must be properly handled by any applications programs. Note that the DOS wedge for the C64 originally exsisted at $CC00-$CFFF. On the 1750 disk a new one is supplied which exsists from $CC00-$CEFF freeing up page $CFxx for the RAMdos. Hedley