[Techtoolslist] Fluke 6809 pod

Tony Jones tony at tonyjones.com
Fri Mar 18 15:12:30 EDT 2016


On Fri, Mar 18, 2016 at 11:27 AM, John Robertson <jrr at flippers.com> wrote:

> These only work with CPUs that can support having their address and data
> lines floated when you select a particular CPU pin, AND that pin MUST have a
> pullup resistor on the UUT PCB. In some cases that pin was simply wired to
> Vcc, and then to able to use the 90 you have to cut the Vcc trace and add a
> 10K pullup.
>
> The 90 works by cycle stealing, it runs when the CPU is on the opposite
> cycle. Rather cute in fact - the game can be running and you can run a RAM,
> ROM and I/O test at the same time!

thanks for posting this technical info John,  much appreciated!


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