[Coco] [Color Computer] Re: 128 or 512?

[Joel Ewy]

I think there's some terminology confusion here.  Individual flash
memory chips, like the ones used in a PC's BIOS, are certainly byte
addressable (at least for reads).  But when flash memory is used in a
Compact Flash card, there is additional circuitry (maybe on the chip,
maybe in a separate chip?) that allows multiple megabytes to be accessed
via an IDE-compatible interface, so you don't have to bring all those
address lines out and have a 150-pin connector.

The issue of limited writes is also important, so neither Compact Flash
cards nor individual Flash ROM chips would be good candidates for
interfacing with the CoCo as RAM.  Write speed is probably also slower
than writing DRAM.  But using individual Flash ROMs to replace ROM-based
software on the CoCo is certainly feasible, and really captures one of
the best qualities of the CoCo (instant power-on availability) while
eliminating the inflexibility of permanently fixing firmware in ROM. 
And of course Compact Flash cards on an IDE interface make good
low-power, silent, small mass storage units.

Oh, and FWIW, I have two 512K CoCo 3s and 1 128K.  Back when I ran
Multi-Vue a lot that 512K came in very handy.  Having a nice big RAMdisk
for temporary storage really sped up things like the C compiler.  I'd
love to see more games that make better use of more than 128K.  And
there'll still be plenty of stuff to run on the old 128K machine.

JCE

Roger Merchberger wrote:
> Rumor has it that John W. Linville may have mentioned these words:
>> On Thu, Mar 01, 2007 at 11:17:40AM -0500, Roger Merchberger wrote:
>> > Rumor has it that John W. Linville may have mentioned these words:
>> > >On Thu, Mar 01, 2007 at 06:42:31AM -0800, Jim Cox wrote:
>> > >> Why James?  Would the issue be the limited writes of the
>> > >> flash cards?
>> > >
>> > >Because CF cards are not byte-addressable?  They look like a hard
>> > >drive, not memory.
>> >
>> > If I'm not mistaken (which I probably am) I *think* there's a mode
>> that _on
>> > reads_ CF cards can be byte-addressed, but I think they can only be
>> written
>> > by erasure & reprogramming in 32K or 64K chunks... but again, it's
>> not like
>> > the CF spec is bedtime reading to me... ;-)
>>
>> I really don't want to quibble over terminology here.  The point is,
>> CF doesn't look like memory (i.e. LDA and STA don't work to read and
>> write any single random byte on the card in any random order).  So,
>> it wouldn't be appropriate to use it for a RAM card.
>
> I'm not trying to quibble, either, but what I was trying to say, is I
> _think_ there's a read-only memory mapped mode -- so LDA's *would
> work.* STAs wouldn't, as you'd have to "format" a block & then
> reprogram the whole sucker, but I'm essentially saying that if written
> correctly the first time, you could set it up as a memory-mapped ROM
> and actually execute programs from it, just like any other form of
> ROM. RAM "functionality," I believe, is outta the question, tho.
>
> Not sure what you'd do with a 16Meg removable SECB chip... but
> technically, I think it'd be possible, and for a 1-off hacker-type
> removable prototyping ROM station, might be kinda neat. "Useful" would
> be an exercise best left up to the hacker, but neat nonetheless. ;-)
>
> Laterz,
> Roger "Merch" Merchberger
>
> -- 
> Roger "Merch" Merchberger  --  SysAdmin, Iceberg Computers
>  _±±_                          zmerch at 30below.com
> (©||®)  If at first you don't succeed, nuclear warhead
>  _)(_   disarmament should *not* be your first career choice.
>
>
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