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From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.sys.apple2
Subject: Re: Best hard drive combo
Message-ID: <16490@smoke.brl.mil>
Date: 22 Jun 91 19:47:22 GMT
References: <1991Jun22.033627.21891@crash.cts.com>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 36

In article <1991Jun22.033627.21891@crash.cts.com> georged@pro-harvest.cts.com (George Dybowski) writes:
>I had the Apple High Speed SCSI card and sold it and purchased the Ramfast
>card.  The Rmafast is worth the extra money.  With the Ramfast you get
>faster speed, more partitioning, and GEOS compatability.  GEOS does not
>work with the Apple SCSI card, I verified this with my own experience and
>from Berkeley Software.  GEOS works fine with the Ramfast card.

I've seen this or a similar message about four times now.  Once would
have been plenty.

While a GEOS user may care about this information, in fact it has no
bearing on which DMA SCSI card is better.  There is no legitimate
implementation for GEOS that should cause it to fail with Apple's
High-Speed SCSI Card.  If it really does fail, that is a serious bug
in GEOS which rightfully ought to be fixed by the publisher of GEOS.

A fair comparison of Apple High-Speed SCSI Card vs. RamFast SCSI Card:
1.  Apple's is less expensive.
2.  RamFast's on-board caching provides faster effective throughput for
ProDOS-8 applications; its effect on GS/OS performance is not so drastic.
3.  Apple's card supports I/O request chaining, which is a big win for
certain special applications (witness the Star Wars movie demo).
4.  RamFast originally did not support SCSI devices such as CD-ROM and
scanners, although by now its firmware has probably been revised to do
so.  Apple's card carefully conformed to the full SCSI spec.
5.  Drivers are available for use of Apple's card with CD-ROM and SCSI.
In general, GS/OS releases will certainly support Apple's card, but may
not fully support RamFast, and Cirtech may be a while in getting new
drivers released for use with new GS/OS releases.
6.  Apple's card automatically disables DMA when accessing the "top"
4MB of the 8MB RAM space, which means that one can utilize 8MB AND DMA
SCSI I/O at the same time with Apple's card.

Generally, I would say that RamFast is preferable if one primarily uses
ProDOS-8, and Apple's High-Speed SCSI Card is preferable if one primarily
uses GS/OS.  Special circumstances could modify that basic assessment.