Re: ZipGS question

[Rubywand <rubywand@swbell.net>]

Charles Claypoole writes ...
> 
> Thats strange..  I didnt know about this - so it is a rom3 thing?  Makes
> sense since the rom1 didnt have trouble doing gsos at all..  Ok..  Do you
> know if the ZipGS does dma?  I cannot remember- the apple hs scsi does - is
> there any advantage of having it on?   Thanks for the info - going to try
> this today..
> 
 ....

     The ZipGS replaces the 65C816; so, it's going to access memory directly.
"DMA" usually means that some board has gotten the main processor to release
control of the memory bus. The board then accesses memory directly 'on its own'.

     An issue with some early ZipGS's (version 1.01) was DMA compatibility--
they were flaky about permitting DMA accesses. (Zip Technology tried to get
these sent in and fixed; so, there probably are not many of the flaky boards
around.)

     The boards which can do DMA are typically disk controllers-- like RamFAST.
(RamFAST comes with a utility, ramfast.sysytem, which allows config changes
including a setting for "TransWarpGS?" and "DMA?".)

     Also, some cards seem to be better at doing DMA than others. Here's a
snip from a 1998 posting by Scott G. ...

>>
My system is a 13.75MHz Zip GS with an 8MB Sirius RAM card.  It has
greater than 1GB of total storage via an Apple High Speed (DMA) SCSI
card.  It is a ROM 3.

With my SCSI card, DMA must be turned off to use 8MB without problems.
I borrowed a RamFAST rev. D card to try and it _does_ work with an
8MB card without problems.

However, at 13.75MHz, DMA just shaves a second or two off booting,
so the loss of DMA is not that bug a deal (ie. 10 seconds with DMA
on and 11 seconds with DMA off, if I remember correctly).

I have used the Sirius with both System 5.0.4 and System 6 (6.0
and 6.0.1).  In all cases and with all GS/OS software, all 8MB
were recognized without a hitch.  RAM disk setup on System 6.0.1
is also not a problem.  I have never tried to set a RAM disk in
System 5.0.4.

The 8MB has no problems at all with my 13.75MHz Zip GS.

All my software is enhanced.  Now I can convert full page
scanned documents (like sample exams and and answer keys) off
the school's web site , convert them using Prism, and print
them out using Platinum Paint.

8MB is really needed and useful if you want to make large
full screen movies with an Apple IIGS.
<<

     As far as I know, the CFFA drive does not do DMA.

     An issue with 8MB Expansion Mem cards is whether or not they allow DMA
to RAM above 4MB; and, if they do, how much of the additional RAM is included.

     There's a good discussion about 8MB cards in the newsgroup archives which
you can access via Google. The thread is named "8MB GS RAM cards" dated around
June 1998.


     You mentioned having a "GS-Ram". If it's a GS-RAM Plus, then you may need
to change an IC to have it work correctly on a ROM 3. Here's a snip from
Adalbert Goertz in the FAQs ...

>>
026- What IC do I need to use the GS-RAM Plus in my Apple IIgs? 

You need the GSPLD1A.1 for a ROM-01 GS and the GSPLD1B.1 for a ROM 3 GS.
<<


Rubywand