shers@masala.lcs.mit.edu (Alexander The Great Sherstinsky) (01/22/91)
Hello, I am going to ask what might seem a stupid question, but here it goes anyway: I am trying to build a new parallel computer as part of my thesis. At my disposal are off-the-shelf components as well as the ability to build custom 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 independent. Does such a beast exist? Or if I am going to design a custom chip for it, how to do it without wasting too much silicon real estate? Any response concerning this matter will be greatly appreciated. -- +-------------------------------+------+---------------------------------------+ |Alexander The Great Sherstinsky|me |shers@masala.lcs.mit.edu|To become as | |Alexander Semyon Sherstinsky |myself|shers@masala.lcs.mit.edu|refined person| |Alex Sherstinsky |I |shers@masala.lcs.mit.edu|as possible. |
jon_sree@world.std.com (Jon Sreekanth) (01/22/91)
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.comfrazier@oahu.cs.ucla.edu (Greg Frazier) (01/23/91)
shers@masala.lcs.mit.edu (Alexander The Great Sherstinsky) writes: >Hello, >I am going to ask what might seem a stupid question, but here it goes anyway: >I am trying to build a new parallel computer as part of my thesis. At my >disposal are off-the-shelf components as well as the ability to build custom >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 >independent. Does such a beast exist? Or if I am going to design a custom >chip for it, how to do it without wasting too much silicon real estate? >Any response concerning this matter will be greatly appreciated. Jon's response was fairly accurate, but I think it danced around the issue that you are addressing. You're building a parallel computer. Since it is for a thesis, I assume that the architecture is unique in some way, and you have identified a need for multi- port RAM. Multi-port RAM is *very* expensive, as far as silicon goes. You would be much better off faking it, i.e. use single-port RAM's and find some way to multiplex them or put them into banks (as Jon basically said). -- Greg Frazier frazier@CS.UCLA.EDU !{ucbvax,rutgers}!ucla-cs!frazier
mmm@cup.portal.com (Mark Robert Thorson) (01/24/91)
Weitek 1066 is a fast multiport register file, if they still make it. I forget exactly what it's got, but I think it's four 16 bit ports and one 32 bit port. You also might check out the product lines of Logical Devices Inc. and AMD. These things are mostly used to build microprogrammed engines for graphics and DSP. The 1066 has 32 32-bit registers.
ram@jetsun.weitek.COM (Ram Ganapathi) (01/25/91)
In article <38398@cup.portal.com> mmm@cup.portal.com (Mark Robert Thorson) writes: >Weitek 1066 is a fast multiport register file, if they still make it. >I forget exactly what it's got, but I think it's four 16 bit ports >... etc. Yup, I do believe Weitek will still take orders for this chip. Check with our marketing/sales dept. (408) 738 - 8400 or 800-HOT-3167 Ram Ganapathi Weitek Corp.(408)738-5765 x2215 Sunnyvale, Calif 94086. uucp : {sun,pyramid}!weitek!ram