CompuServe Messages

Richard >>I understand the flicker eliminator stuff, but I'm a little confused as to the different types of RAM.<< Ok, The 512K on the motherboard is "shared" by both the CPU & Agnus chip. Kind of like shared office space. At any given moment, only one of them can be working in the office, so they take turns with Agnus controling access of the office. Sometimes Agnus is given a big job to do, and must work overtime in the office. Agnus can steal upto three turns, before having to let CPU access the office area. This shared RAM is called "Chip RAM", since the "custom chips" also use it. The CPU also has access to an area of RAM that Agnus can't see or use. The CPU NEVER has to stop or "wait" to access it, so the area is called "Fast RAM". This is the extra memory plugged into the left side of your A500, (including the RAM in the A530). The CPU will use the Fast RAM first, before trying to use the Chip RAM. A third type of RAM is the RAM plugged into the A501 (belly) slot. This RAM isn't used by the Agnus, but is under her control. Kind of like a backroom to the shared memory area. Only the CPU can use it, but the CPU still must wait to access it if Agnus is busy. This RAM area is called "Slow RAM". Slow RAM, does have two advantages. First, the CPU will use it before it uses CHIP RAM, saving CHIP memory. Second, if you use the ECS Agnus the Slow RAM can be reconfigured (hardware hack) to be CHIP Memory for a full 1-meg of CHIP. As is, you appear to have 512K-CHIP + 512K-Slow for 1-meg total. If you convert using the ECS Agnus you could have 1024K-CHIP + 0K-Slow for 1-meg of total memory. The A530 would also give 2-megs of Fast memory. Ron. – ap'ing with AP. (Eagles may fly, but weasels aren't sucked into jet engines.)