[SiriusHardware]

I'm assuming that there is no 'timing' as such in the MK14-side code, as it probably just polls the serial clock input and reads the next data bit whenever the clock changes state from low to high. In that sense it is the sender which controls the upload speed, as long as it does not send so fast that the MK14 is still dealing with the last bit when the next bit is sent, so there will be an upper speed limit which the sender should not exceed. This will also have to be dialled down a little bit (as has been stated) to allow for the the system slowdown when an active VDU is connected.

I can't imagine that a clock speed of 4.00MHz or 4.43MHz will make much difference except that a machine with a 4.43MHz clock could read the code in at a slightly higher maximum speed.

We could potentially make the sender configurable so that it can send at one of four optimised speeds to suit:-

4.43MHz machine without VDU.
4.43MHz machine with VDU active.
4.00MHz machine without VDU.
4.00MHz machine with VDU active.

Currently, the webserver sounds as though it is throttled back for the benefit of the last / slowest case above - but it is still so much faster than any other current loading method that the small speed increase which could be gained by optimisation for the actual system in use is hardly worth worrying about.