16 Dec
2001
16 Dec
'01
2:49 p.m.
Just how does the FPGA fit in here?
With a 179x and a 9229, you need only a pal and an oscillator. With a 2797 and
no need for data rate changes, i.e. 500 KHz only and MFM only, you only need the
2 MHz oscillator for the 2797 and an address decoder with which to generate the
select. You may want some logic to generate the wait-states, else your CPU may
not make it around the horn, so to speak, in a loop that gets in sync and then
stays there at 2 microseconds per bit.
What goes in the FPGA?
Dick
----- Original Message -----
From: "Ben Franchuk" <bfranchuk(a)jetnet.ab.ca>
To: <classiccmp(a)classiccmp.org>
Sent: Sunday, December 16, 2001 5:27 PM
Subject: Re: MITS 2SIO serial chip?
Richard Erlacher wrote:
<snip>
... 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