Xref: utzoo comp.lsi:1314 sci.electronics:17122 Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!world!jon_sree From: jon_sree@world.std.com (Jon Sreekanth) Newsgroups: comp.lsi,sci.electronics Subject: Re: Multi-port RAMs Message-ID: Date: 22 Jan 91 14:31:54 GMT References: <1991Jan22.005718.23369@mintaka.lcs.mit.edu> Sender: jon_sree@world.std.com (Jon Sreekanth) Organization: The World Lines: 33 In-Reply-To: shers@masala.lcs.mit.edu's message of 22 Jan 91 00:57:18 GMT In article <1991Jan22.005718.23369@mintaka.lcs.mit.edu> shers@masala.lcs.mit.edu (Alexander The Great Sherstinsky) writes: chips (with MOSIS). Here is the problem: The architecture could really benefit from having a large 5-port-read, 5-port-write RAM, all ports being Consider some alternatives : a Video RAM has one standard read/write port and one serial read only port. Many vendors make multiport FIFO's; check the non-mainline companies like Integrated Device Technologies. Pick up a copy of EE Times or Electronic Design News for more company names. There may be a few vendors making true multiport RAM's; but I'd be surprised if they made 5 port versions. Another alternative is to use standard fast SRAM's and use external glue logic to time-multiplex the ports (either on-demand, or fixed time window basis). Even if you made a chip out of it, you'd not get much memory out of it. For something like MOSIS' process, you'd be lucky to get a few K bytes worth. Take a look at mask photographs of present day fast CMOS processors (Intel, Digital, AT&T, IBM, others; look at the Proc of Custom Integrated Circuits Conference). On a large sized die with 1 u or less processes, a 8Kbyte cache could take up half the area. MOSIS' process is probably nowhere as good. Best suggestion : use off the shelf SRAM's, that gets you enough Kbytes, and use glue, PLD's or mosis ASIC to convert it into 5 port. Good luck, / Jon Sreekanth Assabet Valley Microsystems Fax and PC products 346 Lincoln St #722, Marlboro, MA 01752 508-562-0722 jon_sree@world.std.com