Re: Apple //e RGB Card's TTL Logic

["josephoswaldgg@hotmail.com" <josephoswald@gmail.com>]

Bryan Parkoff wrote:
> There is no Apple //e RGB Card's schematic existence.  I am able to draw
> my own schematic from scratch by looking at Apple //e RGB Card's TTL chips
> and wiring traces.  I need to use information by converting from 16 colors'
> 4 bits to R, G, B, and H/V sync.
>     I am unable to obtain TTL information to see the inside chip.  Google
> search is complicated.  Do you know where can I find TTL chip directory
> which it has all pinout inside chip?  It is an example of SN74LS173AN chip.
> Are you sure that different manufacturers make the same chip design using
> model such as 74LSxxxx.  I am not sure if SN74LS is same as 74LSxxxx.

Bryan--

  Generally, these are the same. The prefix tends to be a manufacturer
indication. SN is a mark corresponding to Texas Instruments. The 74LS
is a logic family: 74 is a TTL family (40xx is CMOS), and LS is for
"low-power Schottky" ALS is a more modern substitute. The last numbers
indicate the function. The final suffix could indicate a temperature
grade or package material.

  You will also usually see a four digit code which indicates the
manufacture date, typically a two-digit year and two-digit week. 8410
would indicate something manufactured in March 1984.

  I find Texas Instruments' web site to be a good source of data sheets
for this stuff.

  I recommend Horowitz & Hill's "The Art of Electronics" as a good
textbook on this stuff; it is getting a little old now, but is more
than modern enough for Apple II purposes!