🚀 go-pugleaf

> First, I'd like to know how many chips in the ST are
> soldered in instead of socketed, and which these are.
> Please answer this for the early STs, the current models,
> and the future shipments.  I'd like to decide which
> vintage model would be best for doing hardware upgrades
> (piggy back RAM, 68010, etc).
> 
	In all the ST's that I have seen, Only the Glue, MMU, Roms
and Dma chip are socketed. The rest are soldered. Having participated in
4 piggy back memory upgrades, I don't see how socketed memory chips would
help. It would help ofcourse in replacing chips, but then the socket may
be put in at that time.

> More serious:  How can the ST be bus-expanded?
> The *other* brand brings its entire bus to the side connector,
> but the ST has only a read-only 128K game cart socket
> (what, games?  on an Atari??).  How can there be an
> expansion chassis into which we can plug boards with
> lotsa RAM, 32000 co-procs, or whatever else needs some
> direct bus access?  Will we be stuck with a box hung
> off the floppy or hard disk serial ports?
> Which can't be accessed directly?
> Tecmar is already advertising a true expansion box
> for the you-know-what.

Well it depends on how you look at it, if you really need a bus coming
out to the edge. If you do a co-processor box with its own backplane
etc, then all you need the ST for is to do I/o for you. Further, a
hard disk could be used directly without the need for going through
the ST. So now you would need the St for graphics,Screen/Kbd i/o, floppy and
for access to the various ports. If you do the interface right, the
10 Mhz DMA port is plenty fast. I know of two such boxes, the TT 
(apparently it will be announced at the Hanover Fair next month) and
the $199 Ibm Pc compatible 8088 box. Most people who critisize the St
for not having expansion slots fail to point out how many of the ports
that normally sit on expansion cards on things like the Ibm Pc are
built in. Further, a lot of people seem to have the misconception that
a particular hardware subsystem has to sit on processors/backplane bus
for efficiency. If the functinal partitioning is done correctly (ie.
you dont need to get at every signal of the processor/backplane bus,
but just need to pass data fast between the two subsystems, and the
minimum amount of control or state info that you can get away with)
then i claim that the Dma approach is superior (No electrical loads,
simpler control, clean interface beween subsystems, no bus - are some
of the reasons that i come to mind). I am not totally convinced that
a backplane is required. But then I may be totally wrong. Can anyone
convince me otherwise?

(BTW for the price that Tecmar is charging for the expansion box i can
have 3 1/2 St's sitting on my desk!! )
> 
> Finally:  Is it possible to write directly to the graphics
> bitmap in RAM (from an assembler or C program)?
> Where speed is of the utmost, we'll need to be able
> to do our own custom bit-blits, quickdraws, etc.
> to compete with the custom graphics chips in the
> high-priced machine.
> I heard that on one of the machines (forget which)
> you were somehow prevented from direct access to the
> graphics area (this may just be a BASIC restriction,
> as there is no MMU in either machine to stop machine
> code routines from doing it).
> 
	yes you can write directly to screen memory. In fact you can
designate any 32K chunk of memory on a 256 word boundary to be the
screen memory (gets switched at the next Vblank ). In the V blanking
period the screen memory/ pallette can be manupulated to get
interesting effects. It is also possible to dynamically link in your
own handlers for the blanking interrupts.

> Hoping to get an ST soon, mike k
-- 
					Jwahar R. Bammi
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