[Coco] Booting Nitros9.

Dave Philipsen dave at davebiz.com
Tue May 12 00:04:10 EDT 2020

Actually it’s not that recent. Back in the 80s if you could get an EPROM with a 150ns access time, that was considered to be pretty fast. At the same time, you could get a fairly fast SRAM chip with a 70ns access time, twice as fast as the EPROM.


> On May 11, 2020, at 11:13 AM, Alex Evans <varmfskii at gmail.com> wrote:
> This RAM being faster than ROM thing is mostly a (relatively) recent
> phenomenon (like when RAM started to used more complex access
> characteristics to make up for being so slow). On most classic home
> computer platforms it is just as fast or even faster (for instance,
> ROMs were moved into RAM on Amigas because they could be patched, and
> because accelerators had faster access to on board memory than they
> did to system memory RAM or ROM). With things like CoCoSDC, SuperIDE,
> and CoCoFlash, you can rewrite the ROMs easily enough, and I believe
> booting from ROM would be faster than booting from disk.
>> On Mon, May 11, 2020 at 5:41 AM Jeff Teunissen <deek at d2dc.net> wrote:
>>> On Mon, May 11, 2020 at 3:07 AM Dave Philipsen <dave at davebiz.com> wrote:
>>> OS9 could easily be built into ROM. It may be practical for an embedded system where the operating system never gets updated. But you will almost always need some sort of read/write media for a typical system so you might as well just boot the operating system from that media.
>>> Another drawback of using ROMs is that they, and other forms of non-volatile storage, usually have slower access times than RAMs. So you may limit yourself on the maximum CPU speed whereas loading the system into RAM generally means it can run faster.
>> Except on a CoCo 1 or 2, where programs in ROM can run twice as fast
>> as programs in RAM.
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