Under what circumstances is Dual-Ported Ram, DPR, recommended?
DPT is recommended when the communication between the host and PMAC is more than 100 data items per second, as a rule of thumb. A data item is an imprecise term, but basically a line of communications, say X14 Y20 Z25 in a program, or a position or status request. With bus communications, it is the software overhead for a line of communications, not the number of bytes that limits the amount of communications you can do.
