> Update: behaviour seems to be erratic with XST. When the board is left on= , > occasionally, the counter will count up to the 6th and 7th LED and reset > again and not count that high up. 1. Please trim most of old messages off when posting next message on same subject . GMail handles this well and I did not notice the prepended old material until replying. But other browsers may not, and it wastes bandwidth and possibly brain power. 2. I have no experience whatsoever with the systems you are working with so the comments are general. I'm utterly impressed with the games you are now playing and the things you have learned and are learning, especially so when looking back at your not always promising beginnings on list (in 2008?). (That's not intended to be a backhanded compliment). And I note that you were talking about FPGA starter kits in April. Actually beginning to make headway with something 6 months on from a 1st casual inquiry is a jump that all too many never make. (I resemble that :-) ). The reported behaviour suggests 1. the possibility of an intermittent reset condition which normally asserts often relative to display "events", or remains asserted, such that the counter does not seem to be advancing because it is fitting and starting around its reset point. A similat effect may occur if logic is often but not always dropping into some illegal or inconceived state due to a ogical error. Less likely here probably. 2. As it occurs in one language and not the other it suggests it may be due to a difference in boundary condition handling. (In my experience the incorrect or incomplete handling of "boundary conditions" is a major cause of programming errors but seems to get less attention than one my expect). Here this could be register initialisation, treatment of non explicitly defined bits or pins or eg register connections to the world which are part of a larger register which is being set up by the system but which are not expressly being used here. If external undefined pin handling is an issue then literally waving a hand (or a dead fish) near the IC or touching pins with an (only mildly electrostaically charged) finger will often allow a problem to be narrowed down. In lieu of a potentially unsafe (pun almost intended) finger, a say 100k or 1 megohm resistor connected to Vdd (and ground on a second pass) and touched to each pin in turn *may* allow floating or unexpectedly active pins to be identified (by locking them in a set logic state). Resistor value used should be high enough that it will not affect a properly functioning pin. If the problem is internal undefined states this can sometimes succumb to bloody minded brute force initialisation of everything that is used in any way or associated with other material in any way. When writing programs this can include zeroing or preloading all used RAM to known states. expressly setting all ports and pins and registers to known states during initialisation etc. Obviously this does not translate directly into 'HDL coding but the principles are the same. Russell --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .