MITS 2SIO serial chip?

From: Richard Erlacher <edick_at_idcomm.com>
Date: Sun Dec 16 22:45:06 2001

Rochester isn't cheap, but they listed the PLCC-44 parts at $18.10, IIRC. The
last time I bought a WD controller (1979), it cost over $90, so the sticker
shock isn't an issue.


----- Original Message -----
From: "Ben Franchuk" <bfranchuk_at_jetnet.ab.ca>
To: <classiccmp_at_classiccmp.org>
Sent: Sunday, December 16, 2001 5:27 PM
Subject: Re: MITS 2SIO serial chip?


> Richard Erlacher wrote:
> > Why? The WD37C65 is a much easier part to use, and it programs pretty much
like
> > a NEC uPD765, drives the cable directly, and automatically deals with the
> > data/clock separation for 500 KHz, 250 KHz, and 125 KHz data rates at both
300
> > and 360 rpm. You can lift 'em from broken HDC's or order 'em from
> > www.rocelec.com (Rochester Electronics). They're most common in PLCC-44,
which
> > you should be able to handle, even if, like me, you didn't listen to Mom
when
> > she told you to stop that.
>
> It sounds like a nice chip. Since all I have is 3 1/2" 1.44mb drives I
> will
> have a fixed 500 Khz clock, thus less programing. Also the chips are
> cheap
> if you can find them $7.25 _at_ BG micro. I was looking some nec? chips at
> Rochester
> and they were over $75 each.
>
> If you must use a WD part, which I prefer also, then
> > use a WD179x with a FDC9229. That does everything in two chips, including
> > selecting the appropriate clocks. The 2797 uses an analog PLL and, unless
you
> > are satisfied with a single data rate, that means multiple filters and
analog
> > muxes, etc.
>
> Thanks for the info. While a 2 Mhz machine would have been the speed of
> system in the 80's I might as well go to 4 Mhz since the FPGA will run
> that fast.
> As a side note a 2 Mhz machine is about the same speed as a PDP-8. 1.5us
> for a jump.
> 2.5 us for memory access.
> --
> Ben Franchuk --- Pre-historic Cpu's --
> www.jetnet.ab.ca/users/bfranchuk/index.html
>
>
Received on Sun Dec 16 2001 - 22:45:06 GMT