IBM 5151 (MDA display) - common faults / gotchas?

Jules Richardson jules.richardson99 at
Sun Nov 9 12:49:44 CST 2014

On 11/09/2014 12:28 PM, drlegendre . wrote:
> That's nuts.. so not only is the monitor relying on the computer to feed it
> a sane horizontal pulse, but that pulse rate isn't fixed or
> even securely delimited in hardware? Just POKEing the wrong memory location
> or writing bad data to some software register can set a catastrophically
> destructive video mode?

IBM mentality at work, possibly - they figured nobody would be running 
non-IBM software on it, and of course their own software would be tested to 
ensure that it didn't happen :-)

(Weren't certain Commodore PETs susceptible to a similar scenario?)



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