Comments on TTCvi

Comments on TTCvi Programming Model

• FIFOs are ``write only''. No way to read back even persistent (repetitive) mode data. Preferable if FIFO contents, read and write pointers were available in read only memory and registers.
• 24 bit event counter in two D16 registers. Attempt to read with D32 gives bus error.

Other Comments on TTCvi

• Automatic clock generation if no input LHC clock may be dangerous (loose connection?). Ditto for orbit signal.
• No way for software to know whether internal or external clock is being used.
• Default (power up) state should be: no external clock means no output clock or data. Internal clock should be explicitly selected.
• Extra control and status bits for this should be provided.