PFENNIGER%CGEUGE51.BITNET@WISCVM.ARPA (08/07/86)
Can anyone tell me from where can I obtain the circuit diagram for the 128k or 512k versions of the RAM expansion modules for the Commodore 128. Many thanks in advance.
fred@cbmvax.cbm.UUCP (Fred Bowen) (08/11/86)
> Can anyone tell me from where can I obtain the circuit diagram for the 128k > or 512k versions of the RAM expansion modules for the Commodore 128. As far as I know, Commodore is has no plans to publish the diagrams. The RAM expansion modules consist simply of either 64K x1 or 256K x1 DRAMs and the 8726 (custom) controller. The controller itself eliminates the need for TTL address and data buffering. The controller also provides DRAM refresh. The C128 (or C64) processor accesses the expansion RAM via instructions to the controller, which then reads/writes/swaps memory via DMA. The controller drives the bus only during phase 2 of the standard 1MHz system clock. -- Fred Bowen uucp: {ihnp4|seismo|caip}!cbmvax!fred arpa: cbmvax!fred@seismo.CSS.GOV tele: 215 431-9100 Commodore Electronics, Ltd., 1200 Wilson Drive, West Chester, PA, 19380