Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!rutgers!cbmvax!fred From: fred@cbmvax.UUCP Newsgroups: comp.sys.cbm Subject: Re: 1750 Memory Expansion Message-ID: <1095@cbmvax.cbmvax.cbm.UUCP> Date: Wed, 10-Dec-86 14:46:40 EST Article-I.D.: cbmvax.1095 Posted: Wed Dec 10 14:46:40 1986 Date-Received: Sun, 14-Dec-86 07:45:02 EST References: <960001@hplsla.HP.COM> Organization: Commodore Technology, West Chester, PA Lines: 34 > I am looking for technical information on the 1750 RAM module. I have > seen it advertised locally for $169. The advertisement said it is > 512Kbytes in cartridge form for the C64. I would like to find out what > the software and hardware interface looks like. > > Does it use a bank switch technique for addressing 64Kbytes at a time? > Or is it 32Kbytes? > What address does it use for controlling which bank is active? The 1750 RAM module is a 512K byte expansion cartridge for the C128. The 1700 RAM module is a 128K byte expansion cartridge for the C128. The 1764 RAM module is a 256K byte expansion cartridge for the C64. Those diffs aside, they all function alike. The expansion RAM is not a contiguous part of the system. It is accessed via instructions to a DMA controller located at $DF00 (IO-2) in the c64/128 I/O block. It features such operations as Fetch, Stash, Swap, and Compare and a variety of addressing modes. The controller will perform these operations at DMA speed, and can operate on blocks as small as 1 byte or as large as 64K. The 1764 (for use on C64's) requires a beefier power supply, which is included. All modules come with a diskette containing demo programs and examples. The 1764 version comes with a RAM DISK utility; the C128 version of the RAM DISK utility will be finished soon. The C128 in CP/M mode already does support the module as a RAM DISK. Whew. That should suffice as a brief summary. Feel free to ask for details via email. -- 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