ssingh@watserv1.waterloo.edu (The Sanj-Machine aka Ice) (01/29/91)
Could someone help me out please?
I have an Adaptec 1542b with a 296N. I want to add a CDC Wren III.
Question: Will using a cable for a daisy chain type connection be better
or worse than getting another cable and attaching it to the external
connector on the back of the 1542 and routing the cable back into the
case to the Wren (a radial configuration)?
Also, do I need a special SCSI cable to connect to the back. It doesn't
look the same as the internal connection.
One last thing. If I were to upgrade the motherboard speed could I
also change the DMA jumpers on the 1542 to a higher rate? Or does the fact that
the AT bus runs @ 8 Mhz across most systems make this moot?
Thanks very much.
Ice.
--
"No one had the guts... until now!"
$anjay $ingh Fire & "Ice" ssingh@watserv1.[u]waterloo.{edu|cdn}/[ca]
ROBOTRON Hi-Score: 20 Million Points | A new level of (in)human throughput...
"The human race is inefficient and therefore must be destroyed."-Eugene Jarvismartin@unislc.uucp (Martin Cryer) (02/02/91)
In article <1991Jan28.192335.11794@watserv1.waterloo.edu> ssingh@watserv1.waterloo.edu (The Sanj-Machine aka Ice) writes: >Could someone help me out please? > >I have an Adaptec 1542b with a 296N. I want to add a CDC Wren III. > >Question: Will using a cable for a daisy chain type connection be better >or worse than getting another cable and attaching it to the external >connector on the back of the 1542 and routing the cable back into the >case to the Wren (a radial configuration)? > >Also, do I need a special SCSI cable to connect to the back. It doesn't >look the same as the internal connection. > >One last thing. If I were to upgrade the motherboard speed could I >also change the DMA jumpers on the 1542 to a higher rate? Or does the fact that >the AT bus runs @ 8 Mhz across most systems make this moot? > >Thanks very much. > >Ice. > >-- >"No one had the guts... until now!" >$anjay $ingh Fire & "Ice" ssingh@watserv1.[u]waterloo.{edu|cdn}/[ca] >ROBOTRON Hi-Score: 20 Million Points | A new level of (in)human throughput... >"The human race is inefficient and therefore must be destroyed."-Eugene Jarvis It does not matter whether you use the internal or external connection. Just bear the following in mind... If you use the internal cable only, make sure that the device and only the device at each end of the controller is terminated. If the controller is at one end of the cable, keep the terminators in place on the controller and just terminate the device at the other end of the cable. The external connector is just a pass through of the internal connector with an alternative connector type, for which you need a different cable type. If you use the external connector, make sure you remove the terminator packs from the controller and terminate the last device on the external chain. Think of the internal cable and external cable as one piece, so then the drive ate each end will be terminated, and the controller is in the middle and wont be. As for changing the BUS ON/OFF and DMA transfer times, you can get away with less conservative times than default, but it seems dependent upon What often people do here is to use the internal cable and just daisy chain it outside the cabinet through a vacant ISA slot cover hole. Once again just treat the controller as a device and if its in the middle of the cable, remove the terminators and terminate the drive at each end. With this arrangment, be careful of EMI and noise problems as the interface is single ended, keep the distance down and dont run the ribbon cable too close to electrically noisy items etc etc... not only the BUS speed but also your memory subsystem speed too. The Adaptec appears to take liberties with the AT Bus. What I did was up the transfer speed till it stopped working under disk to disk or disk to tape transfers and backed off one notch. Under DOS, the difference between the best and the worst is not noticable, under Unix SVR3 or SVR4 its marginal at best. Be conservative for Unix, the effect of hung transfers is unpleasant.... We currently use this controller without problems with the following motherboards; Intel 301/302 25Mhz ISA bus 386 Intel 303 33Mhz ISA bus 386 Intel 401 25Mhz ISA bus 486 Intel 403E 33Mhz EISA bus 486 Unisys 33MHz EISA bus 486 Also we use the Adaptec 1740 EISA controller too. Martin Cryer Unisys Corp SLC USA, 801 594 5747 All comments my own not those of Unisys Corp etc etc etc