IBM PC printer adapter schematic
ard at p850ug1.demon.co.uk
Fri Apr 6 15:38:18 CDT 2007
> Tony Duell wrote:
> > Are you in England at the moment? If so, I could probably be convinced to
> > snail-mail you a copy of the page from the Techref.
> Now sorted out, but thanks anyway (email burp meant I couldn't reply to say I
> now have it). Ta to those who offered...
I had a quick look in my techrefs last night...
The printer port on the MDA card and the separate printer adapter are
much the same logically, but there are differences in the actual
For example, the MDA card inverts some of the status lines from the
printer using '04 NOT gates. The printer adapter uses '86 XOR gates (XORs
the siangl wirh '1', basically), presuably because they needed an XOR
gate to selectively invert one of the address lines to give the 1st/2nd
adapter address selection.
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