morphed to TTL part number history, was: IBM PLAYING CARDS

Scott Stevens chenmel at
Mon Dec 19 21:06:45 CST 2005

On Mon, 19 Dec 2005 17:56:55 -0800
"Chuck Guzis" <cclist at> wrote:

> On 12/20/2005 at 12:10 AM ard at wrote:
> >I recently bought a second-hand Philips 'upright' reel-to-reel
> >tape  recorder, and found a schematic glued to the inside of
> >the case. At one  time this was quite common on consumer
> >electronic devices I believe.
> Not at all uncommon on radios and TVs using vacuum tubes
> (valves).  Very useful.  But then early PC's sometimes included
> schematics in their end-user documentation.

I was disappointed when the XT-clone motherboard vendors stopped
including the schematic diagram in that little user guide that
always comes with a motherboard.  I have kept all the user guides
I've had that included the schematic.

And the shocking thing is it's always the same schematic.  You can
use that schematic to troubleshoot almost ANY XT clone motherboard
from a certain era.  They all had the same TTL, and usually even
placed on the board identically.

That was the era when IBM lost control of the design of the 'IBM
PC,' and had to 'invoke the PS/2' to try to grab back control of
the market.

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