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- Xref: sparky comp.sys.sun.hardware:3972 comp.dcom.modems:12327
- Newsgroups: comp.sys.sun.hardware,comp.dcom.modems
- Path: sparky!uunet!bif!mike
- From: mike@cd.com (Mike Heins)
- Subject: Re: Does anybody REALLY need 115.2K baud for a modem?
- Message-ID: <BtACq0.8M8@cd.com>
- Keywords: modem serial RS-232
- Organization: Central Data Corp., Champaign, IL
- References: <1992Aug15.150835.1362@lokkur.dexter.mi.us> <1992Aug17.193308.22751@alw.nih.gov> <1031@auratek.UUCP>
- Date: Thu, 20 Aug 1992 14:10:47 GMT
- Lines: 30
-
- In article <1031@auratek.UUCP> dmostrom@auratek.UUCP (Douglas E. Mostrom) writes:
- >In article <1992Aug17.193308.22751@alw.nih.gov>, jwa@yog-sothoth.dcrt.nih.gov (James W. Adams) writes:
- >>
- >> It's time to retire the UART and move on.
- >
- >I'm no hardware engineering guru, but I believe that most serial cards
- >use intelligent ASICs, and not UARTs, to drive serial I/O.
- >
-
- This is not necessarily true. The lowest-overhead serial
- implementations for the SPARCstation are STILL based on UARTs.
-
- There are quite a few SBus serial boards based on the Cirrus Logic
- CD1x0 and CD2x00 chips. But since most of them don't have another
- processor, they end up taking many more interrupts to service serial
- traffic. While the character interrupts are isolated from the SPARC,
- most of the data movement is still done by the TTY driver (meaning the
- SPARC). This results in anywhere from 1% (on the best implementation
- we've seen, from CoSystems) to 4% (on the Sun SPC/S with 1.1
- driver/firmware) of a SPARC 2 being used for every 1000 chars moved.
-
- The lowest-overhead implementations (that I know of) for the Sun still
- have processors and UARTs. These use only .2%-.5% of the SPARC 2 for
- every 1000 chars moved.
-
- Mike Heins
- ------------------------
- Central Data Corporation "Makers of the scsiTerminal Server"
- 1602 Newton Drive (800) 482-0315
- Champaign, IL 61821 mike@cd.com or ..!uunet!cendata!mike
-