Wanted LSI 53C876 data sheet

[Dave (from the UK)]

I'm looking for a data sheet on an LSI chip. It is the 53C876 and is
used as a dual channel SCSI controller.

Any ideas - I looked at the LSI site and was unable to find it, but
perhaps I am looking in the wrong place. All I could find are drivers
for Windows PCs to use SCSI cards based on that chip, which is not what
I want.


I'm thinking of converting a couple of dual channel SCSI cards - one is
single ended (SE) and the other high voltage differential (HVD), so
the boards have one SE and one HVD channel on each board, rather than
two of the same on the boards. I need both SE and HVD in a computer, but
don't want to use two PCI slots.
--
Dave K

http://www.southminster-branch-line.org.uk/

Please note my email address changes periodically to avoid spam.
It is always of the form: month-year@domain. Hitting reply will work
for a couple of months only. Later set it manually. The month is
always written in 3 letters (e.g. Jan, not January etc)

 

[Winfield Hill]

from the UK wrote...

I'm looking for a data sheet on an LSI chip. It is the 53C876 and is
used as a dual channel SCSI controller.

Any ideas - I looked at the LSI site and was unable to find it, but
perhaps I am looking in the wrong place. All I could find are drivers
for Windows PCs to use SCSI cards based on that chip, which is not what
I want.


I'm thinking of converting a couple of dual channel SCSI cards - one is
single ended (SE) and the other high voltage differential (HVD), so
the boards have one SE and one HVD channel on each board, rather than
two of the same on the boards. I need both SE and HVD in a computer, but
don't want to use two PCI slots.

I can post a copy to abse, would that be helpful?

 

[kip]

You have Mail...go get it

 

[Winfield Hill]

kip wrote...

You have Mail...go get it

I have three sym53c876 documents. One is from Symbios Logic,
dated 1996, quite detailed, 281 pages and 15MBytes in length.

 

[Dave (from the UK)]

from the UK wrote...



I can post a copy to abse, would that be helpful?

Thanks, but someone pointed me to an online version

http://www.lsilogic.com/files/docs/techdocs/storage_stand_prod/SCSIControllers/876.pdf
(from)
http://www.lsilogic.com/products/scsi_ics/lsi53c876e.html

It appears what I was thinking of doing (hacking a dual single ended and
a dual high voltage differential boards to make a dual Se + HVD board)
would be quite difficult, since the two PCB layouts of the Sun SCSI
boards in question are quite different.

The SYM22810 (which looks identical to the Sun 375-0005 single ended board)
http://www.lsilogic.com/products/scsi_hbas/lsi22801.html

and the SYM22802 (which I assume is the same as the Sun 375-0006 Sun HVD
board, although I can't verify this)
http://www.lsilogic.com/products/scsi_hbas/lsi22802.html

are far from the same as you can see.

I've verified the 53C876 chip will do both SE and differential, but
getting the other chips hooked up requires more than simply swapping a
few chips from one board to another.

I'd like to find out how on earth a tape drive can be fitted in my
computer (Sun Ultra 80). A DDS-3 tape was available as an option, but I
can't see if it needed a SCSI board.

It is a bit silly really, as the motherboard has two single ended SCSI
controllers, but I can't see how to route either of them to a tape
drive. One does the two internal disks and internal CD, but with no
obvious way of putting a tape drive on there. The other feeds a
connector on the rear, with again no obvious way of attaching an
internal tape drive to that.

There are spaces for 3 internal units - a floppy, CD and one other.
--
Dave K

http://www.southminster-branch-line.org.uk/

Please note my email address changes periodically to avoid spam.
It is always of the form: month-year@domain. Hitting reply will work
for a couple of months only. Later set it manually. The month is
always written in 3 letters (e.g. Jan, not January etc)

 

[Pooh Bear]

It is a bit silly really, as the motherboard has two single ended SCSI
controllers, but I can't see how to route either of them to a tape
drive. One does the two internal disks and internal CD, but with no
obvious way of putting a tape drive on there.

You make a new ribbon cable with an extra connector of course ! Easy.

Graham

 

[Dave (from the UK)]

:




You make a new ribbon cable with an extra connector of course ! Easy.

Graham

I don't think it is as easy as that.

The 68-pin connector on the rear panel is almost certainly mounted on
the motherboard, with no cable.

The other channel, which feeds the SCSI backplane for the two 80 pin SCA
drives would need more than 68 pins, so will not be 68-pins.

I can't switch the machine off now to look and its impossible to remove
the side panel without it tripping a micro switch that disables the
ouput form the power supply.

As such, I don't believe there are any internal 68-pin SCSI connectors.

Someone else hit this problem in a Sun Blade 2000 computer.

http://groups.google.co.uk/group/co...e?lnk=st&q=dds4&rnum=1&hl=en#8a344ceff3c244ee

which is a somewhat similar. Mine is somewhat older, but quad
processors, whilst that is somewhat never and dual processors.

It would appear from the replies he got that for DDS-4, you can use a
narrow connector (50 pin), as the data is only transfered at about 5
MB/s maximum.

--
Dave K

http://www.southminster-branch-line.org.uk/

Please note my email address changes periodically to avoid spam.
It is always of the form: month-year@domain. Hitting reply will work
for a couple of months only. Later set it manually. The month is
always written in 3 letters (e.g. Jan, not January etc)

 

[carl0s]

I don't think it is as easy as that.

The 68-pin connector on the rear panel is almost certainly mounted on the
motherboard, with no cable.

The other channel, which feeds the SCSI backplane for the two 80 pin SCA
drives would need more than 68 pins, so will not be 68-pins.

I can't switch the machine off now to look and its impossible to remove
the side panel without it tripping a micro switch that disables the ouput
form the power supply.

As such, I don't believe there are any internal 68-pin SCSI connectors.

Someone else hit this problem in a Sun Blade 2000 computer.

http://groups.google.co.uk/group/co...e?lnk=st&q=dds4&rnum=1&hl=en#8a344ceff3c244ee

which is a somewhat similar. Mine is somewhat older, but quad processors,
whilst that is somewhat never and dual processors.

It would appear from the replies he got that for DDS-4, you can use a
narrow connector (50 pin), as the data is only transfered at about 5 MB/s
maximum.

I'm still confused. You can buy SCA to 68-pin adapters, and 68pin to 50-pin
adapters. The big problem would be that the bus would run at the speed of
the slowest device.

 

[Dave (from the UK)]

I'm still confused. You can buy SCA to 68-pin adapters, and 68pin to 50-pin
adapters. The big problem would be that the bus would run at the speed of
the slowest device.

The SCSI path is:

motherboard ------>SCA backplane ---->CD-ROM and terminator.

The cable between the motherboard and the SCA backplane does not have
nice simple 68-pin cables with standard connectors.

The cable between the SCA backplane and the terminator (which is part of
the cable) is possibly 68-conductors, but has no standard 68-pin
connector on the SCA backplane.

The end of the cable has a molded conversion to 50 pins and terminator.
The cable might be 68 conductors to the terminator, but I don't know.
There is no reason it needs to be, and the wiring could be non-standard.
So crimping a 68-pin connector here might be risky, especially as a
replacement cable is $400.

I found this manual (page Figure 4-1, Page 4-2 or page 26 in the PDF)
shows the Sun solution, which is a 50 pin extension cable.

http://www.sun.com/products-n-solutions/hardware/docs/pdf/806-4423-10.pdf

However, that is not cheap ($70, plus shipping) considering it is only 3
50-pin IDC connectors on a short length of 50-connector cable. I think
I'll make one of them myself. I can get the parts for about £5 (around
$7), so it is 10% of the price of buying one.

---
Dave K

http://www.southminster-branch-line.org.uk/

Please note my email address changes periodically to avoid spam.
It is always of the form: month-year@domain. Hitting reply will work
for a couple of months only. Later set it manually. The month is
always written in 3 letters (e.g. Jan, not January etc)