Re: RamFast & TWGS Problem

[harold.h@genie.com (Harold Hislop)]

Alexander Siegfried:
 
I (Harold Hislop) wrote:
 
HH>The manual is wrong. Before you install your RamFast, go into
HH>the TWGS CDA and make certain you have the 'AppleTalk/IRQ'
HH>option turned ON. Close the CDA. Now go ahead and install your
HH>RamFast.
 
To which you commented:
 
AS>No, the manual is only partially wrong. Yes, turning the AppleTalk/IRQ
AS>option on will work with the RamFAST. However, this should be AVOIDED
AS>IF POSSIBLE, since it will slow down the TransWarp GS significantly!
AS>Btw, its exactly the same with the ZipGS' IRQ delay!
 
Correct, so far. If possible to avoid this, it should be avoided.
You go on to say:
 
>> For example, in time critical, "hardcore" applications like GS
>> demos turning the IRQ on results in a system's speed that does
>> not differ much from a standard, unaccelerated GS!
 
Sorry, but I don't consider demos to be hardcore apps. Don't get me
wrong, they DO represent some seriously skilled programming in most
cases, but they aren't serious apps.
 
FWIW, the slowdown is, on average approx 5%. The TWGS drops down to
2.9 (2.6, whatever) Mhz from the time the IRQ flag is set until it
gets reset, at whie you had. And congratulations on slowing down your GS.. RamFast crashing is
-usually- caused by low quality SCSI cables, incorrect term, or a
lack of (or low) TrmPwr. If you have a Rev-B or Rev-C board then
flip dip switch #1 back and forth several times, leaving it ON. If
you have a Rev-D then make sure the jumper cap IS installed on both
pins. (the above makes the RamFast supply TrmPwr to the SCSI chain
and can eliminate much grief)

--
-Harold Hislop
Hardware Coordinator,
Apple II RoundTable, GEnie
14Mhz/32k TWGS, 1Mb Rev-C RamFast, Prototype ROM_03 in tower
Heritage Mac hardware also spoken (great IIgs peripherals :)