[Coco] 1 or 2 meg upgrade

Sat Nov 22 00:25:10 EST 2014

I think it made a lot more sense "back in the day" :). Even if you had a
hard drive then, slow seek times alone meant using ram as storage or cache
made big performance improvements.

Today, with flash based storage or even things like Drivewire, the overhead
to access mass storage is tiny.  The gains from using ram as temporary
storage for data are much smaller.  For instance, when experimenting with
the microware c compiler I spent some time setting up a ramdisk to try and
speed things up, but found there wasn't much improvement in compile times
compared to running everything over a DriveWire disk (slow throughput and
CPU intensive but awesome latency/seek time).  The majority of the time was
being spent doing the actual compiling already.  Running off a superide on
flash or cocosdc I'm sure the difference is even smaller.

I suspect a text editor using a small ram buffer but running off modern
storage would be as performant in a majority of cases as one using a lot of
ram to do the same things.  Its a shame we don't have a way to do page
faults on the coco, swapoing would be very very fast and give one all the
"ram" you could want.
On Nov 22, 2014 12:01 AM, "William Astle" <lost at l-w.ca> wrote:

> Back in "the day", I regularly overflowed 512K in OS9. Not only does it
> allow you to run more processes simultaneously, it allows you to have a lot
> more stuff memory resident, which is nice if you're swapping disks all the
> time.
>
> On 14-11-21 09:51 PM, Aaron Wolfe wrote:
>
>> I am surprised you can actually allocate more than 512k under OS9.  I've
>> never had much luck with that.  There is so little room in the system page
>> (which doesn't get bigger when you add ram) that I always run out of room
>> there before running out of free pages on a 512k coco.
>>   On Nov 21, 2014 11:42 PM, "Bill Pierce via Coco" <coco at maltedmedia.com>
>> wrote:
>>
>>
>>> Aaron, graphic screens, get/put buffers, fonts, pointers,
>>> patterns,ramdisks, windows, all live "out" of the 64k workspace and out
>>> of
>>> the 64k system space. Not to mention more processes can be run
>>> simultainiously, who needs more than 521k? Anyone using os9, that's who.
>>> What you're not realizing (or thinking about), is that the system will
>>> automatically use the ram if it's there.
>>> When I had a 512k machine, I was always having to be carefull of how many
>>> text editors I opened, or if I had enough ram to run a graphics program
>>> with all I had running at the moment. With my 1 meg Coco 3, and the Vcc
>>> set
>>> at 2 meg, I do not even think about it. I just do it.
>>> Who needs more than 512k?, that reminds me of Bill Gates saying no one
>>> would ever need more than 64k of memory.
>>>
>>>
>>> Bill Pierce
>>> "Today is a good day... I woke up" - Ritchie Havens
>>>
>>>
>>> My Music from the Tandy/Radio Shack Color Computer 2 & 3
>>> https://sites.google.com/site/dabarnstudio/
>>> Co-Webmaster of The TRS-80 Color Computer Archive
>>> http://www.colorcomputerarchive.com/
>>> Co-Contributor, Co-Editor for CocoPedia
>>> http://www.cocopedia.com/wiki/index.php/Main_Page
>>> E-Mail: ooogalapasooo at aol.com
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Aaron Wolfe <aawolfe at gmail.com>
>>> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
>>> Sent: Fri, Nov 21, 2014 10:55 pm
>>> Subject: Re: [Coco] 1 or 2 meg upgrade
>>>
>>>
>>> On Fri, Nov 21, 2014 at 10:27 PM, Gene Heskett <gheskett at wdtv.com>
>>> wrote:
>>>
>>>> On Friday 21 November 2014 15:43:31 Nick Marentes did opine
>>>> And Gene did reply:
>>>>
>>>>> On 22/11/2014 6:35 AM, Josh Harper via Coco wrote:
>>>>>
>>>>>>    hi guys
>>>>>>
>>>>>> I was just wondering how hard it would be to copy the 1 or 2 meg
>>>>>> memory upgrade boards from disto   as id love to have one of these
>>>>>> myself thanks
>>>>>>
>>>>>
>>>>> Would be nice to see Cloud9 release a 1/2Mb version of the triad.
>>>>>
>>>>> Nick
>>>>>
>>>>
>>>> The Triad is a 1/2 meg board, easy.  But to go to 2 megs you'll need to
>>>> design a circuit that will add 2 more addressing lines to drive the
>>>>
>>> memory
>>>
>>>> mapping of the additional memory in 8k blocks.  One could carry that to
>>>> its logical conclusion at 8 megs, which has been done but while it was
>>>> described in the Rainbow, was not to my knowledge ever a commercially
>>>> offered product.  One of the disto complexities was also the widening of
>>>> the refresh counter, needed to deal with the square architecture of 99%
>>>>
>>> of
>>>
>>>> the memory sticks out there.  For 8 megs, the addressing IIRC expands to
>>>>
>>> a
>>>
>>>> full 24 bits, needing a 12 bit refresh driver, and thats 4 bits wider
>>>>
>>> than
>>>
>>>> the coco's built in dram refresh counter.
>>>>
>>>>
>>> When evaluating whether it's worth all the effort required to extend
>>> beyond 512k, one should really consider why more than 512k would be of
>>> any use on a CoCo.
>>> There isn't any software to actually use this extra RAM besides RAM
>>> disks, and RAM disks aren't all that useful in a world where we have
>>> near zero seek time mass storage like the SuperIDE or CoCoSDC
>>> controllers.  OS9 could theoretically use > 512k, but in practice
>>> you'll usually run out of system resources and/or things to do before
>>> that happens.
>>>
>>> $0.02
>>> -Aaron
>>>
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>>
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