Re: C64 Tower
=============

Subject:      Re: C64 Tower
From:         Fungus - F4CG/Carcass <fungus@c64.org>
Date:         1998/03/09

On Sun, 8 Mar 1998, Lorax wrote:

|On 7 Mar 1998, Marko [ISO-8859-1] M=E4kel=E4 wrote:
|
|> You'll also loose the 9VAC on the user port, but it shouldn't be that
|> crucial, since not many user port devices should need it.  Besides,
|> the 9VAC output was replaced with an 9VDC output in some later
|> models.  You could maybe use a zener also there.
|
|=09Correct me if I'm wrong (and I'm sure many people will) but isn't
|the reason a Commodore needs the AC voltage instead of just straight DC
|the fact that it has no timing crystal and so it relies on the cycling of
|the AC sine was as its timing constant?  At least this is what I was told
|often and repeatedly when I tried to make a portable 64 system run on a
|battery pack.=20


 Actually, the 9VAC is for the tape motor, and also routed to the user port=
 to
power external devices there.

 The only thing it's actually hooked to (looking at the SX64 schematics) is
the TOD clock pin on one of the CIA's.

 The phase 1 and phase 2 clocks are generated by a crystal and the vicII ch=
ip.

/Fungus

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