[Coco] (Probably stupid and newbie-ish) CoCo hardware question

Arthur Flexser flexser at fiu.edu
Tue Jun 26 14:42:08 EDT 2012

Frank, that's the first time I've heard that explanation for why the
CoCo 3 runs in all-RAM mode.  (That Tandy had rights to use, but not
modify, the Microsoft ROMs.)  It seems very plausible to me.  Do you
know this for a fact, or is it just a reasonable conjecture?


On Tue, Jun 26, 2012 at 10:39 AM, Frank Swygert <farna at amc-mag.com> wrote:
> Consult "Tandy's Little Wonder". I think most of the upgrade options are in
> there, but I may not have CoCo1 memory upgrades, I forget! I'd leave a CoCo1
> alone unless it was a E or 285 as well.
> As I reacall, you can't really use all 64K with DECB (RS-DOS if you must).
> The CoCo is mapped so that 32K is ROM, 32K (or less!) is RAM. You can put a
> CoCo2 (and I'd assume a 64K CoCo1) into "all RAM mode" by copying the ROMs
> into RAM. That will let you use a bit more than 32K or RAM in DECB, I think.
> OS-9 puts the computer in all RAM mode as it doesn't use the ROM code except
> a small portion to boot.
> The CoCo3 always operates in all RAM mode. That was necessary to avoid
> copyright infringement of the ECB (Extended Color Basic) code. Tandy had
> rights to duplicate and use ECB, but not to modify it. So the CoCo3 has a
> standard ECB ROM that is loaded into RAM on boot then the SECB (Super
> Extended Color Basic) code it loaded "on top" of it -- SECB is actually a
> patch to ECB that loads upon boot. The SECB code was written by Microware,
> the people who brought us OS-9. I bet Microsoft didn't even want to do it --
> either turned Tandy down or gave them a price they didn't want to pay.  That
> is just a guess though!!
> --
> Frank Swygert
> Editor - American Motors Cars Magazine
> www.amc-mag.com
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