Re: ZipGSx Upgrade Questions (I've read the FAQ's)

[marvinmiller@hotmail.com (Marvin Miller)]

I found some more old info (new) on the reason for changing the 74F00
chip, written by David Empson in '97 as follows;

"I bought the new chip, but, strangely, it has a slower response
characteristic, according to it's specs, than the version that is
already installed."

"Yes, that is right. I think the issue is more related to the power
consumption, voltage levels or driving/loading characteristics, rather
than the speed. (The 74F00 is significantly faster than would be
needed on the fastest possible ZIP GS, and the 74HC00 is fast enough"

Anyway, I hope that sheds some light on it. I have a question now
about the cache RAM;

Are the TAG and Data rams the same chips? I understand the needs for
different chip speeds between the two, but other than that, does the
fact that one is called TAG and one is called DATA mean that the chips
themselves are different?

TIA;
Marvin (Getting Closer to The Order) Miller



On Sun, 12 Nov 2000 19:41:21 GMT, marvinmiller@hotmail.com (Marvin
Miller) wrote:

>Joshua;
>
>That's fantastic help! I can now pick out the exact chip needed for my
>parts order.  Another question though, are you familiar with the Zip
>cards and why some are reccommending a 'slower' chip (74HC00) to make
>the card work at faster speeds?
>
>Also, I'll be posting one last question about the cache memory chips
>required. Can you keep your eyes out for it? I think it will be
>another question similar to the 74F00 etc.
>
>Thanks a Million !
>Marvin Miller
>
>On Sun, 12 Nov 2000 01:31:29 -0500, Joshua Falken
><BrassHat@CrystalPalace.com> wrote:
>
>>The 74F00 is a Quad 2 input Nand.
>>that is to say there are 4 two input Nand gates.
>>The F is about 2 to 6 Nanoseconds faster then the HC
>>74F00 Breaks down as follows
>>The 74 indicates the TTL Logic Family
>>The F indicates the Technology (Fast)
>>The 00 indicates the function (Quad 2 input nand)
>>Letters that precede 74F00 i.e. SN74F00 indicates the manufacturer TI.
>>Letters that follow 74F00 i.e. 74F00N indicates the package i.e.
>>dual-in-line, small outline, or leadless chip carriers. plastic or
>>ceramic etc.
>>The common technology designators for the 74xx series are
>>   = standard
>>LS = Low Power Schottky
>>S  = Schottky
>>ALS= Advanced Low Power Schottky
>>AS = Advanced Schottky
>>F  = Fast
>>HC = Highspeed CMOS
>>AC = Advanced CMOS
>>This info is from the TI and RCA data books.
>>
>>Hope this Helps...
>>
>>
>>
>>On Sat, 11 Nov 2000 22:27:08 GMT, marvinmiller@hotmail.com (Marvin
>>Miller) wrote:
>>
>>>Hi Folks;
>>>
>>>
>>>I'm trying to assemble a lit of the items & part numbers of components
>>>needed to upgrade my Zip GSx 1.02. 
>>>
>>>I've read the FAQ's and searched the newsgroups to obtain all info
>>>regarded to this process and I still have some questions.
>>>
>>>** Replacing the 74F00 chip with the 74HC00 one **
>>>
>>>I have found that it's a 14 pin DIP. Doing a search on Digikey and
>>>narrowing it down to one manufacturer (FairChild) and Package to
>>>14-DIP still brings up a numerous possibilities.
>>>
>>>The 74HC00 questions seem to arise out of the IC Function and Number
>>>of Circuits variables. Can anyone help to isolate the _exact_ one I
>>>need?
>>>
>>>Some of the possibilities IC Functions are;
>>>
>>>2 Input NAND Gate, Inverter, 2 input AND Gate, Buffer, Inverting
>>>Schmitt Trigger, 8-bit Shift Register, 2 Input OR Gate, D Type Flip
>>>Flop, 2 Input Exclusive OR Gate, 2 Input NOR Gate, Binary Counter (4
>>>bit), Bilateral Switch etc.
>>>
>>>Some of the possibilities on Number of Circuits can be;
>>>
>>>Quad, Hex, Octal, Dual etc.
>>>
>>>*** Going from .600 --> .300 on the Cache Chips ***
>>>
>>>It looks like I've found what I needed here. From the DigiKey catalog
>>>what's needed is (4) A504-ND Goes from .600 --> .300 using 28 Pin DIPS
>>>
>>>*** Oscillators ***
>>>
>>>Listings from DigiKey show both;
>>>CMOS TTL Full Size &
>>>Full Size
>>>
>>>Are these interchangeable? IE: Does the CMOS spec make it different?
>>>
>>>Once I get through this and have the right parts, I'll post a part
>>>number list for all the items needed from DigiKey and whathaveyou, so
>>>someone can just order the stuff without doing this leg work. I
>>>couldn't find the ness. info in the FAQ's. To me it seems you still
>>>have to have a pretty decent underestanding of electronics to make iot
>>>from the the FAQ to ordering.
>>>
>>>Thanks for your help;
>>>Marvin Miller
>>
>