Posted By
JamesD
on 2016-10-03
17:27:02
|  Re: What would I do differently in the Plus/4
Just a few points here.
If it were easy, there would have been several faster 6502 machines.
Changing the processor speed probably violates one of the key points of the topic. It's probably going to require a change to the TED. At least back then. Bil Herd even mentioned shortages of 74LS chips at that time, let alone high speed DRAM.
The key example here cited as proof it's possible is the BBC Micro, but when Acorn tried to make it price competitive with the Electron, the machine was clocked half as fast. Acorn had difficulties with the chip that reduced the parts count, and they reduced the speed to reduce the cost. There's a reason the Acorn Electron was designed to use slower RAM. Even after that, it was more expensive than the Spectrum which was the type of machine the TED was targeted at.
Implementing something like this now might seem trivial, but back then it's a huge deal.
BTW, the 6509/6516 part I mentioned was something proposed by Synertek, supposedly originally for release in early 1979.
It was to be called the SY6516 and is first mentioned in Micro issue 21 (Feb 1980) Page 11.
It's also mentioned in issue 22, 23, and 24. In 24 Synertek denies it's existence.
There are some followup letters in response to the articles, but talk of an improved 6502 pretty much end by the time Micro adds 6809 support in issue 37.
It was supposedly designed to be source compatible with the 6502 but not binary compatible.
For an all new machine I don't see that as a huge issue, but people using a monitor that are used to existing opcodes may disagree.
*edit*
I couldn't find the reference in issue 21, I think the page may be missing from that scan.
Issue 23 page 9 has the original article on page 36.
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