IBM PC 5150 with no drives?

From: Russ Blakeman <rhblake_at_bigfoot.com>
Date: Mon Mar 15 17:16:13 1999

The light pen was generally asociated with the video card until EGA came along.
Most dropped the light pen connector. One of the "multifunctions" of the 6 was
real time clock. AST's SixPak has added memory, RTC, 2 serial ports (one is
socketed for optional UART and driver chips), parallel and joystick (I think
joytick, my brain hurts today).

Tony Duell wrote:

> > > > IBM's braindead decision to have 5 (instead of 8) expansion slots meant
> > > > that aftermarket "multifunction" cards became quite popular. MANY of
> > > > them advertised SIX functions; after memory, serial, parallel, and
> > > > joystick, how many people remember what purported to be the other two
> > > > functions?
>
> [...]
>
> > Wasn't it a light-pen ? Or is that covered under serial ?
>
> I would be _very_ suprised if that was the case. The easiest way to
> implement a light pen is to use the signal from the light pen sensor to
> latch the current video refresh address on the video card. The 6845 chip
> (used on the CGA nad MDA cards) has an input just for this. And on both
> of those cards that input is wired to a little header plug, to connect to
> a light pen.
>
> Trying to build a lightpen on anything other than a video card would seem
> to be insane...
>
> >
> > ciao larry
> > lwalker_at_interlog.com
> >
>
> -tony
Received on Mon Mar 15 1999 - 17:16:13 GMT