Hi Ryan
Can you say a few words about how the in-place corner turner works? I'd
be fascinated to hear.
Thanks
Gerry
On 3/1/2013 11:28 AM, David MacMahon wrote:
Thanks, Ryan,
The problem was actually in the integration buffers. We were using QDR vector
accumulators and the vector was too long for the smaller chips. Anyway, the
design has since been retired so it's a moot point for us now, but the in-place
QDR corner turn sounds interesting!
Dave
On Mar 1, 2013, at 10:37 AM, Ryan Monroe wrote:
Hey David,
I know it's probably too late, but I figured out how to do a QDR-corner turn
without ping-ponging (thus, doubling the effective size of the QDR). Give me a
shout if you need this in the future!
On 03/01/2013 10:23 AM, David MacMahon wrote:
Hi, Jack,
We noticed that one of our designs gave bogus results when run on a ROACH 1
board with a serial number in the range 02XXXX, but valid results when run on a
ROACH 1 board with a serial number in the ranges 03XXXX or 04XXXX.
After much head scratching, we opened up one 02xxxx, one 03xxxx, and one 04xxxx
roach. The 02xxxx roach (020247) had Cypress CY7C1263V18 QDR chips, which are
2Mx18 bits. The 03xxxx roach (030144) had Cypress CY7C15632KV18 chips, which
are 4Mx18. The 04xxxx roach (040122) had NEC D44647186AF5-E25 QDR chips, which
are also 4Mx18.
The 2Mx18 bit QDR chips of the 02xxxx roaches can only store 1M (1,048,576)
32-bit words which was too small for our design.
Hope this helps,
Dave
On Mar 1, 2013, at 12:27 AM, Jack Hickish wrote:
Hi All,
Is someone able to confirm that the size of the QDR chips on ROACH 1 boards
depends solely on the board version? If this is indeed the case, does anyone
know the QDR specs for the different board iterations?
Cheers,
Jack
--
----------------------
Gerald R. Harp, Ph.D.
Director, Center for SETI Research
SETI Institute
