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

Frank Swygert farna at amc-mag.com
Tue Jun 26 10:39:30 EDT 2012

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

More information about the Coco mailing list