[Coco] Booting Nitros9.
dave at davebiz.com
Tue May 12 00:07:41 EDT 2020
Actually OS9 neither cares nor knows whether a module is stored in RAM or ROM. As long as the data is there on the bus when it is addressed is all that matters.
> On May 11, 2020, at 1:42 PM, Alex Evans <varmfskii at gmail.com> wrote:
> Doesn't OS-9 search ROM for modules and mark for access so that they
> can be used by the system, so they don't have to be copied into RAM.
> Wasn't that the idea with the module in the FP ROM?
>> On Mon, May 11, 2020 at 1:09 PM Gene Heskett <gheskett at shentel.net> wrote:
>>> On Monday 11 May 2020 12:14:51 Alex Evans 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.
>> Actually Alex, its pretty much maches niches, it still takes the coco3 11
>> seconds to move a megabyte. Disk or ram, I have tested both.
>>> 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>
>>>>> 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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>> Cheers, Gene Heskett
>> "There are four boxes to be used in defense of liberty:
>> soap, ballot, jury, and ammo. Please use in that order."
>> -Ed Howdershelt (Author)
>> If we desire respect for the law, we must first make the law respectable.
>> - Louis D. Brandeis
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