[comp.sys.amiga] SCSI Speed

tdwest@orchid.waterloo.edu (Terry D. West) (03/02/88)

In article <43597@sun.uucp> cmcmanis@sun.UUCP (Chuck McManis) writes:
>                               And in truth the limiting factor becomes
>the SCSI interface, which in its Asynchronous mode is limited to 1.25
>Megabytes per second. 		  ^^^^^^^^^^^^^^^^^

I posted an article requesting info about the 2090, but nobody replied :-(
Is it kosher to send mail to CATS people?

I assume the 2090 cannot do Synchronous SCSI, but it would not be 
difficult at ALL to build a 5 MBYTE/s (yes 5x10^6 8 bit chunks/second)
synchronous SCSI host adapter for the amiga (I could do it in a weekend).  
Undoubtably, there are SCSI drives out there that can do synch 
(Adaptec's higher priced controllers can)... 

So can FFS handle a 5 Megabyte transfer rate?

BTW, when are we actually going to get FFS??? 
	(other than, as is usual, 3 weeks before the folks in the US do :-)

Terry D. West
4B Computer Science/ Elec Eng
watmath!orchid!tdwest

root@sbcs.sunysb.edu (SBCS Systems Staff) (03/03/88)

In article <12330@orchid.waterloo.edu>, tdwest@orchid.waterloo.edu (Terry D. West) writes:
> I assume the 2090 cannot do Synchronous SCSI, but it would not be 
> difficult at ALL to build a 5 MBYTE/s (yes 5x10^6 8 bit chunks/second)
> synchronous SCSI host adapter for the amiga (I could do it in a weekend).  

	Terry, no problem building a 5 mByte/sec drive -> interface controller,
	but you won't get more than 14.318Mhz/(2*4) words (= 3.579 mBytes/sec)
	per second out of the Amiga bus.  This arises from the fact that
	you have to look like a 7.159 mHz 68000 when driving the Amiga bus,
	ie each word transferred takes 4 ticks of the cpu clock.  Of course,
	you could put a load of shared memory on the controller card and do
	your DMA to that memory, but that's another controversy :-)
	
> Undoubtably, there are SCSI drives out there that can do synch 
> (Adaptec's higher priced controllers can)... 

	I suspect that the only spindle you'll get more than ~3mByte/sec
	out of are the (still expensive) PTD drives that Fujitsu, etc
	make.  To the best of my knowledge, no one makes a PTD -> SCSI
	controller.

> Terry D. West
> 4B Computer Science/ Elec Eng
> watmath!orchid!tdwest

						Rick Spanbauer
						SUNY/Stony Brook

bill@cbmvax.UUCP (Bill Koester CATS) (03/03/88)

In article <12330@orchid.waterloo.edu> tdwest@orchid.waterloo.edu (Terry D. West) writes:
>
>I posted an article requesting info about the 2090, but nobody replied :-(

You can get the A500/A2000 Technical reference manual by sending $40 US to:

	Commodore Business Machines
	Attn: Lauren Brown
	1200 Wilson Drive
	West Chester, PA 19380

>Is it kosher to send mail to CATS people?
>
I guess it wouldn't hurt to try.



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