Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!rutgers!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: IBM cards in the Amiga
Message-ID: <13428@cbmvax.commodore.com>
Date: 25 Jul 90 17:24:01 GMT
References: <1990Jul20.172301.6908@watdragon.waterloo.edu> <13381@cbmvax.commodore.com> <82425@tut.cis.ohio-state.edu>
Reply-To: daveh@cbmvax (Dave Haynie)
Distribution: comp
Organization: Commodore, West Chester, PA
Lines: 79

In article <82425@tut.cis.ohio-state.edu> erd@giza.cis.ohio-state.edu (Ethan R Dicks) writes:
>In article <13381@cbmvax.commodore.com> daveh@cbmvax (Dave Haynie) writes:
>>In article <1990Jul20.172301.6908@watdragon.waterloo.edu> rbharding@trillium.uwaterloo.ca (Ron Harding) writes:
>
>>>    What we are thinking of is a bus-adapter board which uses the
>>>Bridgeboard slot to connect the IBM slots to the Zorro bus.  

>>That's something we've been proposing for years.  It's called a "dumb"
>>bridge card; basically just a bus translator to go between Amiga and
>>PC/AT.  

>The WEDGE for the A1000 and A500 does it.  It does not autoconfigure, but
>it does map PC/XT I/O space into Amiga memory space ($EA0000 by default)

I have heard about the WEDGE, but it's not a correct or complete solution.
Not being an autoconfig card, it is not a Zorro II card and may not work
in all backplanes.  And it can easily cause conflicts with other cards.  The
other thing is that it only maps I/O, not PC memory as well.  While that's
certainly better than nothing, there are quite a few interesting things for
the PC bus that are memory rather than I/O mapped.  Also, as I understand
it, the WEDGE is not a completely general purpose bus translator, but 
designed for a subset of IBM cards, mainly (though not exclusively) to get
at the el-cheapo PC-XT ST-506 controller cards.  Of course, a good percentage
of the cards out there are only simple 8 bit cards, so perhaps that's not
much of a problem.

>I have had a Western Digital style PC/XT disk controller on my A1000 since 
>1987.  I get about 120Kb/sec under FFS.  It doesn't blaze, but it isn't DMA.
>I paid less than $400 for new 20Mb drive, WEDGE and Western Digital WX-1 in
>1987.  

The lack of DMA isn't your only problem.  Assuming the WEDGE does a fairly
efficient job of bus conversion, you're still talking to a slow, 8 bit card.
And the disk drive is probably about as slow as they get -- the 20MB Western
Digital IDE drives I've seen sport a seek of about 80ms.  Decent 16 bit 
non-DMA controllers for the Zorro II bus with decent drives attached can give 
you 500kB/s+.  Still, you buy a hard disk not only for speed, but capacity.

>One of the main advantages a bus adapter is the ability to have networking 
>hardware and a hard disk for little outlay.  

Of course, someone must write the driver code.  If you get the WEDGE and the
recommended XT drive, you're OK.  If you're planning to add a PC bus Ethernet
card and actually do something useful with it, you have a great deal of work
on your hands at present -- the software it comes with won't be any use to
you.

>Cheap extra ports are really nice too; how much is the multi-serial port 
>board from C-A or ASDG?

I think the A2232 lists for about $50 a port.  I don't know what they actually
sell for.  Of course, the A2232 also has its own CPU to keep the overhead of
that card fairly reasonable; a dumber card might go for less.

>How much performance do *you* really need?  

Me?  More that we'll be seeing this year, I assure you.  But every generation
is getting closer.

>A person who bought an Amiga to do wordprocessing and to use a database 
>program and other mundane tasks isn't really going to scream about
>the difference between 600Kb/sec and 200Kb/sec on hard drive access.

That's true.  There are plenty of folks who were happy with C64s and floppy
disks.  A cheapo hard disk at any likely speed will keep lots of people happy,
and you certainly don't need 180 Megs (what I have here) to support a little
text editing.

>So... the $64 question is... "Would it really sell?"

The other 1/2 of the "dumb bridgecard" issue is support of the high-end or
niche markets.  There are boards you might use in a lab environment or other
strange places that you can only get on PC bus.  

>-ethan
-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
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