bergan@horizon.COM (Charles Bergan) (08/24/90)
I am going to be building a single board computer to buffer a communications line and was wondering if anyone had any recommendations for easy to use dynamic RAM controllers for the 68000. I'd like to use 1 meg x 9 simms. Blazing speed is not important, I could live with a few wait states. thanks in advance, charles charles bergan Science Horizons, Inc. bergan@horizon.com bergan@balrog.horizon.com ...!ucsd!ncr-sdd!horizon!bergan
alvitar@xavax.com (Phillip Harbison) (08/25/90)
In article <407@horizon.COM> bergan@horizon.COM (Charles Bergan) writes: > I am going to be building a single board computer ... and was wondering > if anyone had any recommendations for easy to use dynamic RAM controllers > for the 68000. Signetics has several nice DRAM controllers that require minimum support chips and support the 68000-style control signals, i.e. the generate then /DTACK or /DSACKi signals. Here are a few part numbers and descriptions. 74F764 supports 256K DRAMs, 68000-style interface, separate refresh clock, address latching, arbiter for dual-port access 74F764-1 same as above, but designed for reflected wave switching 74F765 same as the 74F764 but without an address latch 74F765-1 same as above, but designed for reflected wave switching 74F1761 68000 or 68020 interface, programmable DRAM timing generates DRAM and mux control signals (requires external address mux). Includes an interrupt priority encoder and vector generator. 74F1762 address mux for the 74F1761. Supports 4Mb DRAMs. 74F1763 supports 1Mb DRAMs, programmable timing, page-mode accesses, and burst-mode refreshes after page-mode accesses. 74F1764 same as 74F764 but supports 1Mb DRAMs 74F1765 same as 74F765 but supports 1Mb DRAMs 74F1764-1 same as 74F764-1 but supports 1Mb DRAMs 74F1765-1 same as 74F765-1 but supports 1Mb DRAMs There were preliminary specs on other interesting DRAM controllers in the 1989 FAST data book; however, these might still be vaporware so I won't bother to list their features. Needless to say, Signetics seems to be specializing in 68K-compatible DRAM controllers. You might also check out National Semiconductor. They also have a wide variety of DRAM controllers; however, they are not specifically oriented towards the 68K family. Samsung second-sources some of their controllers. AMD still makes some DRAM controllers, and Motorola secound-sources some of those parts. Like the NSC parts, they are general purpose building blocks and not specifically oriented towards the 68K. -- Live: Phil Harbison, Xavax, P.O. Box 7413, Huntsville, AL 35807 Uucp: alvitar@xavax.com Bell: 205-883-4233, 205-880-8951
caveh@csl.sri.com (Caveh Jalali) (08/25/90)
>In article <407@horizon.COM> bergan@horizon.COM (Charles Bergan) writes: > I am going to be building a single board computer ... and was wondering > if anyone had any recommendations for easy to use dynamic RAM controllers > for the 68000. > since you seem to be willing to live with wait states, you might consider doing most of the work in software. executing a list of 512 nop instructions every 8ms (if memory serves correctly) is plenty. add a pair of (address) multiplexors and you're in business. worked for me. -- __ 00c -- caveh@csl.sri.com ICBM: 37d 27' 14" North, 122d 10' 52" West
kevinw@portia.Stanford.EDU (Kevin Rudd) (08/27/90)
In article <20449@hercules.csl.sri.com> caveh@csl.sri.com (Caveh Jalali) writes: >>In article <407@horizon.COM> bergan@horizon.COM (Charles Bergan) writes: >> ... recommendations for easy to use dynamic RAM controllers for the 68000. > >since you seem to be willing to live with wait states, you might consider >doing most of the work in software. I believe that Motorola has an applications note complete with schematic and software (with usual disclaimers) to accomplish this design. Also, for fancier designs (more for 030+) I believe that Samsung has some pretty fancy chips that were announced earlier this year. I think that they do the laundry and dishes while they aren't doing refreshing... -- Kevin