Date   : Wed, 11 Nov 2009 22:58:42 +0000
From   : afra@... (Phill Harvey-Smith)
Subject:  Dragon/Tandy macjhines, was  Who the message is from...

Alex Taylor wrote:
> 2009/11/11 Jules Richardson <jules.richardson99@...>:
>> Phill Harvey-Smith wrote:
>>> Nitros9 (re-write of OS9 for CoCo/Dragon)
>> That caught my attention :-) OS-9 seems to be a pretty slick OS
>> from what I've seen - very low resource usage, but very capable.
>> Not sure why it never gained more of a hold in the market, to be
>> honest.
> 
> It can't help too much that most of the Dragons and Tandys in the UK 
> seem to have 32K of RAM or less. I've had 5 or 6 Dragon 32s, but the 
> only 64

It is indeed true that most of the Dragons around are 32K machines,
though some of them actually have half working 64K chips (as do Sinclair
Spectrum 48K machines, as a bank of 32K).

Though a fair number of the enthusiast machines have been upgraded (see 
below).

> I've seen in the flesh was at one of the retro shows. I also once had
> a silver-coloured CoCo, that was even smaller (16K I think). They all
> went on eBay eventually.
> 
> I know the Dragon 32 can be expanded to 64K, but it would seem that 
> most solutions involve in-depth hardware hacking, rather than a
> simple ready-made add-on board.

For Dragon 32s it does indeed I've done a few now and it does involve 
de-soldering (or cutting out, and then removing the legs of) the old RAM 
chips and then fitting 64K chips, and in some cases re-routing the -5V 
and +12V lines away from the new RAM.

For the Silver CoCo 1 machines, it's normally actually easier to do, as 
these are often fitted with one of :

8 4K by 1 bit chips 4K total
8 16K by 1 bit chips 16K total
8 64K by 1 bit chips 32K/64K total

In the case of the latter, this may be the half good ones for 32K, 
either way the chips are normally socketed so upgrading is just a case 
of removing the 8 existing chips, changing the voltage jumpers and then 
fitting the new 64K chips. Some older machines do however need a couple 
of patch wires to fully use the 64K.

Cheers.

Phill.

-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.