(from rob-in design review, 15-Sep-1997)
- UR DI-RATE
- Fragment Arrival Rate
-
Estimate for 33MHz i960RP ~= 75kHz, i960RD runs at 66MHz.
- UR DI-EFS
- Event Fragment Size
-
Page size programmable via PLD -- event size depends on page size.
- UR DI-IDR
- Input Data Rate
-
Bandwidth of buffer memory = 4 * 33 MB/s;
link clock can be faster (depends on input fifo), but average bandwidth
=< 132.
Start/end control word on S-LINK -- recognised by hardware.
- UR DI-FC
- Flow Control
-
XOFF on data input controlled by control bit which operates
automatically at pre-programmed level on the free-page fifo, or toggled
by software.
-
* Input fifo could still overflow --> add in XOFF control by
input-fifo half-full (use 2nd control bit).
-
* Pin for L1-inhibit still desirable on prototype -
from separately programmed free-page fifo level.
- UR DI-EXP
- Data Expansion
-
Final system.
- UR DI-ALLO
- Buffer Space Allocation
-
ok
- UR L2-BS
- Buffer Size
-
1 MB planned -- ok for prototype
- UR L2-ROI
- RoI_request Handling
-
ok
- UR L2-REJ
- L2_reject Handling
-
ok. Buffer manager accepts message with list of up to 100 decisions.
- UR L2-ACC
- L2_accept Handling
-
ok
- UR L3-OUT
- L3 Data Output
-
L3-request rather than L2_accept triggers data transfer.
Incomplete URD table irrelevant?
Ratio of input rate to output rate for original T2B was 3:1, but in the
current design is not yet tied down -- wait to see what is needed in
practice.
- UR L3-WAIT
- Wait for L3_done
-
ok
- UR CTL-SC
- State Changes
-
Run control yet to be defined.
- UR CTL-CONF
- Configuration
-
Reprogrammable ROM on board.
- UR ERR-TRANS
- Transmission Error
-
S-LINK has an error line that can be pulled down, but errors can also
be flagged in last two data bits. Error information is only really needed
on an event-by-event basis, thus error line serves no purpose beyond what
is in the control words.
-
Error line is available in rob-in status register and control words get
written into memory. Status bits get or'd over all words in an event and
written into the used page fifo; since the used page fifo has to be read
anyway this is an efficient place to put link error info (e.g. start
without end, end without start, etc.).
-
Start of event is written both at end of previous event and beginning of
new event. Data with no start is ignored (since it had been agreed earlier
that the rob-in should start cleanly and not in the middle of an event).
-
Should a dummy fragment be generated or allowed to go into memory?
What if the control word is illegal?
Start and end are actually human-readable nibbles ("BOB" and "EOB"), but
they differ in only a couple of bits. Bit 30 is sufficient to distinguish
between them.
- UR ERR-FBIG
- Fragment Too Big Error
-
An event is limited to a maximum of the number of pages allowed per
event in the index table. After that pages get thrown away.
- UR ERR-FERR
- Fragment Contains Error
-
Final system.
- UR ERR-MON
- Error Monitoring
-
Negotiable, ambiguous -- don't worry at this stage.
- UR ERR-DATA
- Dataflow Errors
-
Unknown TTC_ID: historical -- no longer any TTC input!
- Orphan fragment: historical -- no longer any TTC input!
- Unknown RoI_request: ok
- Unknown L2_accept: ok. Triggered by L3_request, rather than L2_accept.
- Unknown L2_reject: ok
- Forgotten fragment: Current implementation has a "stale fragment" list
-- best that can be done?
- L3_done not received: Current software assumes an L3_done will be
received and handles it like an L2_reject. Else it becomes a stale fragment.
- UR ERR-REC
- ROB-IN Recovery
-
Final system.
- UR GBL-MON
- Monitor Data Handling
-
To be defined (by DAQ -1?).
- UR GBL-HIST
- History Maintenance
-
A "sliding window" history of messages is implicitly provided by the
circular message buffer.
- UR GBL-PERF
- Performance Recording
-
Final system.
- UR GBL-ACC
- External Access
-
ok
- UR GBL-AUTO
- Auto-Test Mode
-
No room for self-contained data injection into the input fifo.
- S-LINK test mode should be ok -- seen as a series of "start" control
words. Therefore SLIDAS can be used, with test mode initiated by control
word written by the rob-in.
- UR CON-SIZE
- Size Constraint
-
This is assumed in the design spec. It should be possible to accomplish when
test points and JTAG connections are removed from debug PCI version!
- UR CON-POW
- Power Constraint
-
This is an area for concern, particularly in view of the power required
by S-LINK (SCSI destination requires 3-4 Watts, Fibre Channel even more.
PMC spec allows 7.5 W total, though RIO2 documentation refers to only 4 W.
-
* May need to arrange special cooling and/or remote S-LINK module (via,
for example, the RHUL S-LINK to cable adapter board).
- UR CON-COST
- Cost Constraint
-
Final system, but does not seem unreasonable.
- UR CON-RC
- Run Control Interface
-
Final system.
- UR CON-MON
- Monitor System Interface
-
Final system.
- UR CON-EB
- ROB-OUT Interface
-
ok
- UR CON-L2
- Level-2 Interface
-
ok