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Old 25 August 2018, 14:20   #206
idrougge
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Join Date: Sep 2007
Location: Stockholm
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Quote:
Originally Posted by plasmab View Post
When you do this kind of stunt on an 8 bit machine you use the stack pointer for either the Source or destination and push/pop as appropriate. So it’s like having one Amiga address register that has the (Ax)- syntax only.
Except the 6502 can't move its stack pointer.

It works for the Z80, though.

Quote:
Originally Posted by plasmab View Post
But as already stated the RAM of the era could do 70ns... that’s one 14mhz clock cycle. This is why I complain... these machine waste so much of their available RAM bandwidth
The A1000 and A500 (at least rev 5 and earlier) used 150 ns memory. Perhaps even slower in the A1000.
70 ns memory, if it even existed in 1985, was too expensive for personal computers.

Quote:
Originally Posted by plasmab View Post
Yes. Actually I get and know all of the reasons. If only they'd make the chips in their catalog without the silly designs. i.e. the 030. They dont make it anymore
I think you could ask Rochester Electronics to make them for you. However, costs might be prohibitive.
https://www.rocelec.com/part/BTOFREREIMC68020CRC33E

Quote:
Originally Posted by plasmab View Post
Well it was a bit of a troll on my part. I've seen a lot of premature optimisation in my career that actually led to unmaintainable software that didn't actually perform that well.
You can also regard the 68000 as an expression of this. A transistor count of 68000 was quite huge for a CPU in 1979, much of which was "wasted" on microcode. But the use of microcode allowed Motorola to get their CPU out much earlier than the competitors (Z8000, NS32016 etc) and with much fewer bugs thanks to use of higher-level design methods than placing gates manually.

Last edited by idrougge; 25 August 2018 at 15:09.
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