Re: CGA monitor on a Laser 128

[david@uow.edu.au (David E A Wilson)]

jruschme@hiway1.exit109.com (John Ruschmeyer) writes:

>In article <5i3a7l$40s$1@news3.alpha.net>,
>bheinz  <bheinz@hawk.phantasy.com> wrote:
>>John Ruschmeyer <jruschme@hiway1.exit109.com> wrote:
>><snip>
>>: Taking a page from the recent Laser 128 discussions, I've also pulled
>>: mine out of storage and set it up. Personally, I've decided to go the
>>: color monitor route by using an old IBM CGA monitor and a Laser 128 RGB
>>: cable. I won't get a chance to try it until this weekend, but I suspect
>>: it should work very well.
>>
>>I'm not sure that a CGA monitor will work with the Laser, depending on the
>>refresh rate of the monitor (it needs to be 15Mhz, not the modern standard
>>30, but and old CGA MAY support this.)

That should read 15kHz rather than 30kHz. CGA monitors are 15.75kHz/60Hz just
like NTSC color TV (in fact the old CGA cards in PCs had an RCA jack to allow
the composite video to be displayed on a standard TV - hence the poor [by
current standards] resolution of 640 or 320 by 200). The old IBM monochrome
monitor used on the MDA and Hercules cards is 18.2kHz/50Hz so is not usable
on an Apple //.

The only thing to watch out for is the polarity of the Sync pulses - I have
a Hitachi monitor that did not work on a CGA laptop because the laptop had
+ve sync on one of the two pins (H or V).
--
David Wilson	Dept CompSci Uni Wollongong Australia	david@cs.uow.edu.au