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From: phil@brahms.amd.com (Phil Ngai)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Dual monitors
Message-ID: <1991Feb20.222116.16524@amd.com>
Date: 20 Feb 91 22:21:16 GMT
References: <8130@davidsys.com> <1991Feb12.010248.7563@cs.mcgill.ca> <8345@davidsys.com>
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Organization: Advanced Micro Devices, Inc; Sunnyvale, CA
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In article <8345@davidsys.com> douglass@davidsys.com writes:
|Excuse me, but you're *WRONG*.
|I've already run a test that indicates otherwise.
|I know of projects where this 'limitation' was 'overcome'.
|The 'problem' lies in the timing of the address lines coming from the
|16-bit slot.
|To put it simply, if the card responds quickly enough, there is NO PROBLEM.
|(If the motherboard and/or card is not designed well enough, the card can
|never respond 'quickly enough'.)

That's the whole point. Some motherboards are implemented in such a way that
the 128 Kbyte limit exists. If you want to talk about selected systems,
sure, you can get around it. But in general, it is not safe to mix
8 and 16-bit devices within a block of 128 Kbytes.

|Now, with all of that out of the way, we all realize that the Video ROM
|for the [EV]GA (at C000) is 8-bit.  Right?
|By your argument, that would mean that all of C000-DFFF must be 8-bit?
|Including your 16-bit ExPANded memory board (EMS)?
|Including your 16-bit (memory_mapped) Network board (WD, 3COM, etc)?
|Including your 16-bit nifty fast (memory_mapped) SCSI board?
|Including your 16-bit (memory_mapped) tape backup board?

Indeed, it must be. And I find that the EMS boards I look at have an
option to put them into an 8-bit mode. Other products may have this
controlled by their BIOS. My network board is 8-bit also.

|Try doing benchmarks, people.  It's really not that diffucult.

Try looking at some motherboard chip specs. It's much more useful
than taking a small sample and assuming it applies to all machines.

--

It is time for California farmers to share in the water
shortages that the cities have endured for 5 years.