21 Sep
2008
21 Sep
'08
7:05 p.m.
Subject: Re: Z80 home brew with FDC
From: Eric Smith <eric at brouhaha.com>
Date: Sun, 21 Sep 2008 14:43:09 -0700
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at
classiccmp.org>
Alexis wrote:
It can also be done with a small amount of ttl. Of course the 37C65 if
you can find it or salvage it off an old PC floppy/ide board will be
far lower parts count.
Allison
The other thing that puts me off is the data
clock separator. How are you
doing this?
I can't speak for Andrew, but if you're not using an FDC with a built-in
data separator, the easiest way to do it is to use the SMC 9216, 9229,
or 9239 digital data separator chips, some or all of which were
second-sourced by Western Digital. Of course, they were obsoleted by
the newer FDCs with internal data separators.
Eric
22 Sep
22 Sep
2:38 a.m.
Allison wrote:
It can also be done with a small amount of ttl.
An analog PLL data separator using a 74LS629 VCO or the like is fairly
easy to make, though you do have to be somewhat careful with the PCB
layout. IIRC, such a design is given in the 179x app note.
Building a good digital data separator out of TTL takes a fair number of
parts, which is why it was so rarely done. The DPLL design in the 179x
app note isn't very good.
Eric
10:12 a.m.
Hi
Its a shame that the more easily available 555 chips don't
work well into the Megaherts. They are easy to get and a
pair of them would have made a reasonable separator.
I have a schematic for the separator used on my Polymorphic
computer. It uses another hard to get VCO chip. It uses
a MC4024, an external charge pump, 96L02 oneshot and
a few more TTLs.
Dwight
Date: Sun, 21 Sep 2008 23:38:07 -0700
From: eric at brouhaha.com
To:
Subject: Re: Z80 home brew with FDC
Allison wrote:
_________________________________________________________________
Want to do more with Windows Live? Learn ?10 hidden secrets? from Jamie.
http://windowslive.com/connect/post/jamiethomson.spaces.live.com-Blog-cns!5…
It can also be done with a small amount of ttl.
An analog PLL data separator using a 74LS629 VCO or the like is fairly
easy to make, though you do have to be somewhat careful with the PCB
layout. IIRC, such a design is given in the 179x app note.
Building a good digital data separator out of TTL takes a fair number of
parts, which is why it was so rarely done. The DPLL design in the 179x
app note isn't very good.
Eric
12:56 p.m.
On Monday 22 September 2008 10:12, dwight elvey wrote:
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Hi
Its a shame that the more easily available 555 chips don't
work well into the Megaherts. They are easy to get and a
pair of them would have made a reasonable separator.
I have a schematic for the separator used on my Polymorphic
computer. It uses another hard to get VCO chip. It uses
a MC4024, an external charge pump, 96L02 oneshot and
a few more TTLs.
Dwight
I may actually have some of those, they were used in certain versions of the
c64 along with the 74LS629...
Date: Sun, 21
Sep 2008 23:38:07 -0700
From: eric at brouhaha.com
To:
Subject: Re: Z80 home brew with FDC
Allison wrote:
_________________________________________________________________
Want to do more with Windows Live? Learn ?10 hidden secrets? from Jamie.
http://windowslive.com/connect/post/jamiethomson.spaces.live.com-Blog-cns!5
50F681DAD532637!5295.entry?ocid=TXT_TAGLM_WL_domore_092008 It can also be done with a small amount of ttl.
An analog PLL data separator using a 74LS629 VCO or the like is fairly
easy to make, though you do have to be somewhat careful with the PCB
layout. IIRC, such a design is given in the 179x app note.
Building a good digital data separator out of TTL takes a fair number of
parts, which is why it was so rarely done. The DPLL design in the 179x
app note isn't very good.
Eric 
3:24 p.m.
On Mon, Sep 22, 2008 at 12:56:56PM -0400, Roy J. Tellason wrote:
On Monday 22 September 2008 10:12, dwight elvey
wrote:
Where was there a 96L02 in the C-64?
As it happens, I do have quite a few 96L02s lying around. I was just
wondering what they were good for. Now I know.
-ethan
--
Ethan Dicks, A-333-S Current South Pole Weather at 22-Sep-2008 at 19:20 Z
South Pole Station
PSC 468 Box 400 Temp -73.3 F (-58.5 C) Windchill -118.0 F (-83.3 C)
APO AP 96598 Wind 17.2 kts Grid 27 Barometer 677.7 mb (10715 ft)
Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html
Hi
Its a shame that the more easily available 555 chips don't
work well into the Megaherts. They are easy to get and a
pair of them would have made a reasonable separator.
I have a schematic for the separator used on my Polymorphic
computer. It uses another hard to get VCO chip. It uses
a MC4024, an external charge pump, 96L02 oneshot and
a few more TTLs.
Dwight
I may actually have some of those, they were used in certain versions of the
c64 along with the 74LS629...
8:52 p.m.
On Monday 22 September 2008 15:24, Ethan Dicks wrote:
On Mon, Sep 22, 2008 at 12:56:56PM -0400, Roy J.
Tellason wrote:
There wasn't, though the early versions of the board used a MC4024 and a
74LS629 along with a couple more common LSTTL parts.
On Monday 22 September 2008 10:12, dwight elvey
wrote:
Where was there a 96L02 in the C-64? Hi
Its a shame that the more easily available 555 chips don't
work well into the Megaherts. They are easy to get and a
pair of them would have made a reasonable separator.
I have a schematic for the separator used on my Polymorphic
computer. It uses another hard to get VCO chip. It uses
a MC4024, an external charge pump, 96L02 oneshot and
a few more TTLs.
Dwight
I may actually have some of those, they were used in certain versions of
the c64 along with the 74LS629... As it happens, I do have quite a few 96L02s lying
around. I was just
wondering what they were good for. Now I know.
I think I have one, and one 9602, both probably salvaged from scrap terminal
boards. I remember talking to a guy on the phone while the company I was
with at the time was evaluating a dual cassette deck, intended to be hooked
up to the H11 system I'd built for them. I was trying to prototype some sort
of an interface card (never did get that working), and the guy on the other
end of the phone was very much against the 74123 and LS123, though my
recollection of the exact problem with them is a little fuzzy. Temperature
instability, perhaps, or something of the sort. I only mention this
because it would seem to explain the use of the 9602 or 96LS02 when the whole
rest of the board was more standard TTL...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
23 Sep
23 Sep
7:06 a.m.
dwight elvey wrote:
I have a schematic for the separator used on my Polymorphic
computer. It uses another hard to get VCO chip. It uses
a MC4024, an external charge pump, 96L02 oneshot and
a few more TTLs.
I thought that since it was not pll based, that sort of data separator
was subject to drift (as would a 555 based design?)
maybe I should look at the schematic before commenting - it may have
feedback? i'm having flashbacks to mfm hard disk days.
-brad
5:28 p.m.
Dwight Elvey wrote:
I have a schematic for the separator used on my
Polymorphic
computer. It uses another hard to get VCO chip. It uses
a MC4024, an external charge pump, 96L02 oneshot and
a few more TTLs.
Brad Parker wrote:
I thought that since it was not pll based, that sort
of data separator
was subject to drift
If it's a typical design, the VCO and charge pump are used as part of a
PLL. The MC4024 (note - NOT a CD4000 series CMOS part!) or SN74LS629
are the most common VCOs for "discrete" PLL data separator designs.
Neither is particularly hard to find in small quantities.
Eric
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8 comments
7 participants
participants (7)
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ajp166＠bellatlantic.net -
brad＠heeltoe.com -
cclist＠sydex.com -
dkelvey＠hotmail.com -
eric＠brouhaha.com -
ethan.dicks＠usap.gov -
rtellason＠verizon.net