[Coco] Buffered cable

[jdaggett at gate.net]

Mike

You will need to place noninverting buffer chips like 74LS244 on the 
address line for certain. The MC6809 has external pullups on the 
motherboard but this is not sufficient to drive any large capacitive 
load or a cable over more than about 2 inches long. The data lines 
are already buffered so the real problem is the address lines. 

A real weakness of the design. Tandy must have not wanted to 
spend the extra $1 and have them on board. The pullup resistors 
are marginal at best. 

james


On 11 Jan 2005 at 15:18, Mike Warns wrote:

Date sent:      	Tue, 11 Jan 2005 15:18:12 -0800 (PST)
From:           	Mike Warns <mikewarns at yahoo.com>
To:             	coco at maltedmedia.com
Subject:        	[Coco] Buffered cable
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> I have this old "lunchbox" PC sitting under my desk that just
> whispered to me that I should put a CoCo3 in it.  The VGA monochrome
> plasma screen would probably work fine enough with one of the
> composite to VGA adapters and the keyboard with an AT to CoCo adapter
> and there is enough room in this for a Multi-Pak if I turned it
> sideways.  However, Marty Goodman drummed into my head the need for a
> buffered cable if you are going to separate the MultiPak any distance
> and I've never seen how to do it.  Any plans or ideas out there?
> 
> 
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