byte/word -> dsp is faster than byte/word -> st ram (both byte and word take the same amout of time)
long -> dsp is much slower than long -> st ram
I noticed the slow longword access but I didn't properly time any of the DSP stuff back then. I only recently noticed the DSP is faster than STRam. During the '90s I had assumed it was actually slower!
reading from a memory location, from fastest to slowest:
(byte) DSP -> 030
(byte/word) ST RAM -> register
(word) DSP -> 030
(long) ST RAM -> register
(long) DSP -> 030
That's a useful breakdown - thanks!
ST RAM:
reading from ST RAM is much slower than writing!
Also immediately after reading or writing, the next (trivial) opcode can be free providing it is not a nop (It may even be more than one opcode under some circumstances).
e.g. 'add Dr,Dr' can be absorbed.
For the read case, the read value should be deferred for at least 1 op or the CPU stalls.
However this is from memory and might not all be correct - I started verifying all this stuff again recently but have put it aside temporarily while working on BM.
D.