stepping machanism of Apple Disk ][ drive (was Re: Heatkit 51/4 floppies)

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Mon Apr 12 08:51:36 1999

> I didn't want to descend into the gate-level details of the CPU, but merely
> to count clocks for comparison's sake.

Since the clocks are applied in such a different fashion the comparison is
meaningless.

> clock ticks to access memory while a 6502 took only one. As I've said in
> previous posts, the comparison at the memory bandwidth level came out in

Meaningless unless that is a particular requirement of an application
HARDWARE.

> the fastest commercially available Z-80 with the fastest commercially
> available 6502, the 6502 will win by a wide margin EVERY time. Compare the
> Z80H (1983 or so) with the Synertek SYC6502C (1979) and you'll see that
> 8 MHz Z-80 can't be counted on to win the race. If you like, you can

Your dreaming again. Seriously weve beat the dead horse and it's time to
quit. The 6502 is a good cpu but the comparisons are getting silly.

If you really want to compare archectecture I'll take the T-11 (PDP-11 on
a 40 pin dip) _at_7.5mHZ and blow the both out of the water. here a part
from The same era that has all the addressing modes of the 68k and then
some and can use memory like the 6502 or z80 with its registers. Things
like position independent code, relative addressing and two address
structure are all there. the problem is the arguement is specious as I
can also use the CMOS PDP-8 part to put up as good a battle of who wins.
And getting a PDP-8 into a FPGA has been done as well.

> compare the 8 MHz Z-80H with the Rockwell 65C102, which takes a 4x clock.
> Now it takes 4 clock ticks at 16 MHz to execute a bus cycle of any type.
> Feed it an 8 MHz clock, it will still outdistance the Z-80H.

YEs and the z180S part takes a 33mhz clock, whats the point? CLOCKS and
counting them is meaningless unless they mean something comparable.

> I remember what it was like trying to get delivery on 2147's back in
'81. I

There were peole sellign 4kx1 22pinparts at near firesale prices compared
to 2147 and were near 65ns. They were of the pseudo static three voltage
generation but the y were cheap.

> machines of the early '80's. That might be worth a look. What I want is a

Smallc had limited optimization. I've used it for other cpus and it's fat.
I would ahve guessed that was ported to near everything but it's not a
production compiler though I guess it could be used as one.

> I recently bought a couple of single board dedicated boards, and found that
> they had the 4 MHz Rockwell CMOS parts on them. I didn't think I'd ever see
> something like that in the scrap box. Oh well, once I've figured out the
> memory map, they'll be useful for 1-of's.

I have 4 or 5 board from telvideo 905/955 terminals and they have 65C02s
from rockwell on them. I also have a trackstar 128 (APPLE II for PC) that
has two 65C02s.


Allison



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> >Allison
> >
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Received on Mon Apr 12 1999 - 08:51:36 BST