[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: [N8VEM-S100:983] i960 / V96BMC ~BLAST timing

Darn this thing is beginning to get complicated!  Can anybody give a guess
what the max 80386 clock frequency  we could expect with say a 1" long
ribbon cable connecting two boards with say two IDC type sockets (100
connections) on each board.  For such a short length of "cable" is 33Mhz out
of the question to address DRAMS with 74ASxxx drivers on one or both ends.


John Monahan Ph.D
e-mail: mon...@vitasoft.org
Text:    mon...@txt.att.net

-----Original Message-----
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On
Behalf Of Terry Sare
Sent: Monday, July 16, 2012 7:10 PM
To: n8vem...@googlegroups.com
Subject: Re: [N8VEM-S100:983] i960 / V96BMC ~BLAST timing


You can get free versions of SPICE to do models with. I have not used it
since -- err never mind.

I asked the FA engineer about that at work today (he was ranting about
signal integrity on SAS interface) and he expressed the same concerns about
using ribbon style connections at those speeds as Rob. I asked about the
twisted pair ribbon cables like the used on SCSI 3 cables and he said some
sort of drivers and termination might work.

LVDS and MLVDS drivers. It comes in multi-point and point to point and can
drive ribbon cables.
TI examples
SN65LVDM1676 - 16-Channel LVDM Transceiver
SN65LVDM1677 - 16-Channel LVDM Transceiver

The other one is SER/DES but those are point to point only. Used in LCD,
HDTV, and networking links.
70 data lines down to 10 serial at high data rate.


On 7/16/2012 8:04 PM, John Monahan wrote:
> We could go with a daughter card Rob, we did one with our SMB (a far
> simplier situation of course). The only reason I like the over the top is
> has a better potential to be a bus in itself with perhaps other cards
> up later.   Width is not really an issue. Could we not have alternating
> ground lines.  It's total length would potentially be less than seen on a
> typical old 386 PC motherboard.  I would anticipate having something like
> 74AS645 and 74AS533 to sharpen up the signals as they arrive on the
> board.
> No I have no tools. Suggestions?
> John
> John Monahan Ph.D
> e-mail: mon...@vitasoft.org
> Text:    mon...@txt.att.net
> -----Original Message-----
> From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On
> Behalf Of Rob Doyle
> Sent: Monday, July 16, 2012 5:21 PM
> To: n8vem...@googlegroups.com
> Subject: Re: [N8VEM-S100:981] i960 / V96BMC ~BLAST timing
> On 7/16/2012 5:12 PM, John Monahan wrote:
>> Really anxious to see how you do with high capacity DRAMs/conrtroller.
>> It really would be great to have a GB capacity S-100 board since DRAM
>> SIMMS are so cheap these days.  On top of that, any RAM layout would
>> be generally applicable to any 80386 SBC type of setup since our
>> ribbon cable "over the top" connection is our choice of lines.  The
>> S-100 aspect just makes communication/storage etc. simpler.
>> John
> I would be concerned about the signal integrity of an "over the top"
> connection operating a '386 memory speeds.
> I would think that a daughter card would be a much better idea even if the
> card occupied two s-100 slots.
> Do you have any tools to simulate signals?
> Rob.