Re: Dead II+ Rev.7 motherboard

["Vince Briel" <vbriel@removethisspamcamcast.net>]

HCT is High-speed Cmos, TTL compatible. The big difference is all output and 
input pins need to be used where-as standard TTL, LS, etc doesn't require 
this to be true. In other words, you can't leave output pins floating. You 
need to figure out what you touched, you might have smoke a different IC 
than the 74LS11. $.35 for a 74LS11 isn't too bad.

Vince
-- 
Making computers fun again
replica 1 SE now in production
http://www.brielcomputers.com

"Bryan Parkoff" <nospam@nospam.com> wrote in message 
news:yhHDg.6217$o27.5781@newssvr21.news.prodigy.com...
>
> "Michael Black" <et472@FreeNet.Carleton.CA> wrote in message 
> news:ebncpm$b9s$1@theodyn.ncf.ca...
>> Linards Ticmanis (ticmanis@gmx.de) writes:
>>> Linards Ticmanis wrote:
>>>
>>>> Replacing the LS11 didn't help.
>>>
>>> I should add that I only had a 74HCT11 available as a replacement, which
>>> maybe is not close enough in timing to a real 74LS11 to accurately
>>> create the LD194 signal.
>>>
>> That HCT is CMOS, and the issue may be incompatibility with the lower
>> power schottkey devices already in the II.  Before you panic too much,
>> get the proper 74LS11.
>>
>>  Michael
>>
> Hello,
>
>    When you look at several chips at Apple II+'s motherboard.  It is not 
> wise to combine HCT chip and LS chip.  It requires to use the same power 
> where it is flowing on the logic circuit.  All S and LS chips are used.
>
> Bryan Parkoff
>
>