carl@DISTANCE (Carl Tollander) (12/08/87)
In the November Byte, page 14, there is an article "Controller Chips Add More Zip to SCSI". Mentioned is the Logic Devices L5380 SCSI controller chip, which is reputed to double the data transfer rate of the SCSI interface. The article says that the chip is designed to be a direct substitution for the NCR 5380, which is used in the Mac. After wading through the article, I infer that what we have here is actually a chip set, with one used in the hard drive and one used in the Mac itself, and that no other modifications are necessary other than to replace the chips. I expect to obtain a Mac II soon with a Jasmine Inner-90 hard drive, and am understandably interested in such a chip swap. I don't know enough about about SCSI interfaces yet to tell if this (the swap) is just wishful thinking, or if there is something to it. Has anyone tried this? I'm not sure that it would be worth it if the drive could not take advantage of the extra interface speed. -------------------------------------------------------------------------- Carl Tollander ARPANet: carl@ads.com
kaufman@Shasta.STANFORD.EDU (Marc Kaufman) (12/08/87)
In article <8712072213.AA00774@distance.ads.arpa> carl@DISTANCE (Carl Tollander) writes:
-In the November Byte, page 14, there is an article "Controller Chips
-Add More Zip to SCSI". Mentioned is the Logic Devices L5380 SCSI controller
-chip, which is reputed to double the data transfer rate of the SCSI
-interface. The article says that the chip is designed to be a direct
-substitution for the NCR 5380, which is used in the Mac.
-After wading through the article, I infer that what we have here is
-actually a chip set, with one used in the hard drive and one used in
-the Mac itself, and that no other modifications are necessary other
-than to replace the chips.
....
-Has anyone tried this? I'm not sure that it would be worth it if the
-drive could not take advantage of the extra interface speed.
The 5380 is a very low level implementation of SCSI, and every bus state
transition requires an explicit write to the chip, unless you are using
DMA. As the Apple does not use DMA for SCSI transfers, I cannot imagine
that there will be any improvement in transfer rate if you change chips.
Marc Kaufman (kaufman@Shasta.stanford.edu)dlw@hpsmtc1.HP.COM (David Williams) (12/09/87)
nope. but the innerdrive 90 is a screamer! I have it in one of the Mac IIs here versus the std 40 meg drive apple has in our other mac and the I90 hauls!!
kwallich@hpsmtc1.HP.COM (Ken Wallich) (12/09/87)
>Has anyone tried this? I'm not sure that it would be worth it if the >drive could not take advantage of the extra interface speed. ---------- I don't know if it will work, but would be VERY interested to know if it does. I have a CDC WrenIII which has a faster tranfer rate than my MacII can use. I have a FAST hard drive, but would really like to take advantage of the fastest transfer rate possible. In other words, if you have get a CDC Wren III (the Jasmine drive you mentioned is a Wren III also) or other drives with <20ms transfer rates, I think it would be well worth doing something, if something can be done. When will these wimpy desktops be fast enough? (big :-)) -------------------- Ken Wallich *My views are mine, and mine alone* Consultant "Slimey? Mud Hole? my HOME this is!" DCI kwallich@hpsmtc1.HP.COM @Hewlett Packard ...hplabs!hpsmtc1!kwallich "Why am I soft in the middle, when the rest of my life is so hard? - P.Simon"
garyr@hpmwtla.HP.COM ( Gary Rensberger) (12/09/87)
Using the L5380 in the Mac will offer no speed improvement over the NCR5380, the speed is limited by the device driver running in the Mac. The L5380 does use much less current then the NCR5380 though. -Gary Rensberger