From: "Andrew Lynch"
> Implementing floppy IO can take on many variations and picking the FDC
> is just the first of many challenges [FDC1793? NEC765? SMC9266?
> WD2797?]. What about the data separator? Few chips remain and viable
> sources are scarce. Even integrated FDCs with built in data separators
> are not readily available.
The WD1770/1772/1773 is still my favorite "almost no external
circuitry" chip, but they're getting harder to find, in spite of
being used on Atari and Commodore boxes. You don't need to buffer
the floppy interface and the things have integrated data separators--
and come in a 28-pin package.
I wonder if it might be practical to implement an FDC in a uC or even
a CPLD.
Common sense might be to use an IDE-interface floppy, such as a
Superdrive (again, getting scarce) or implement a USB UHCI to
interface to USB floppies (still easy to find). I shudder to think
at the effort and space required to implement a USB stack in Z80
code, however.
Cheers,
Chuck
> Date: Sat, 14 Jun 2008 22:27:44 -0700 (PDT)
> From: Sellam Ismail
> I only know where the ones are that I know of :) I am discovering roughly
> 2 new ones out in the wild every year or so, though I expect that trend to
> drop off sharply over time as I've already located 42 so far and my
> research tells me that there are probably (PROBABLY) no more than 50 still
> in existence.
I suspect that many of them are still in the Bay Area--I vaguely
recall a Homebrew meeting or two where they were being sold to the
membership for a substantial discount off the $666.66 retail price.
Of course, the S-100 clan didn't think much of the board. After all,
it was just a board...
Cheers,
Chuck
>
>Subject: Re: CP-M Z80 home brew computer circuit board
> From: "bfranchuk at jetnet.ab.ca" <bfranchuk at jetnet.ab.ca>
> Date: Sun, 15 Jun 2008 11:06:33 -0600
> To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
>
>Andrew Lynch wrote:
>> -----REPLY-----
>>
>> Hi! Thanks Jim for the comments. Please let me address the issues raised
>> by Ben:
>>
>> If you look closely at the SBC design, you'll notice it has a feature even
>> better than a floppy controller -- it has a fully buffered IO bus! It
>> contains all the Z80 signals brought out to the DIN 41612 connector. The
>> peripheral bus adheres to the published ECB standard.
>>
>> If you want floppy IO, the solution is simple -- just design one and attach
>> it to the bus! I have already done this with my Disk IO board (IDE and
>> NEC765 FDC) which plugs into my home brew ECB backplane along with the SBC.
>> Assuming there is enough interest in these home brew SBCs, I hope to make a
>> PCB version of the Disk IO board.
>>
>Well when you get a PCB of the Disk I/O board , I'll take the set of PCB's.
>Will a 8272 (intel) Disk controler replace the NEC765? for the floppy
>controler
The 8272 and 765 are interchangeable and available.
If you can find a WD37c65 thats far less pars to implement fdc.
Myself I'd suggest to Andrew to not mess with floppy. Everyone has
their own idea of what to use and how it should be done and what
formats it MUST support.
>for the track formatting for CP/M? Unicorn Electronics is my favorite
>shopping for electronic parts and I can find a 8272 there.
JDRmico has them too.
Having done way to many floppy based sytems and having many on hand
doing something without the noise, power needs and limited space
is a welcome change. Sonmetimes working with cpm is not about
floppies but instead the OS itself.
Allison
>
>>
>> Yes, this SBC is a slightly modern variation of a vintage Z80 CP/M design.
>> I relaxed some of the traditions to make it affordable, reliable, and still
>> useful. The P112, while an excellent design and a wonderful SBC, costs $165
>> for a kit when it is available. I know of no other hobbyist Z80 projects
>> where one can purchase the PCB.
>>
>> There are many Z80 designs available, however, without a PCB it means most
>> hobbyists will have to use temporary breadboards, wire wrap, or prototype
>> boards. None of those lend themselves to long term reliable solutions --
>> especially for a wide range of hobbyist builders.
>>
>> The SBC PCB is meant to be *low cost* and the *common* element of a home
>> brew computer with *simple* IO. Adding unnecessary and complex IO
>> peripherals increases PCB area and cost, raises part count, and pushes away
>> the hobbyists it is meant for.
>>
>> Selecting IO has to be done very carefully. Not everyone who builds this
>> SBC wants floppy IO. I have had numerous requests for many forms of IO
>> ranging from SCSI, IDE, floppy, CF, SD, USB, the Zilog peripherals, etc.
>> There is no solution which will satisfy everyone.
>>
>> Implementing floppy IO can take on many variations and picking the FDC is
>> just the first of many challenges [FDC1793? NEC765? SMC9266? WD2797?]. What
>> about the data separator? Few chips remain and viable sources are scarce.
>> Even integrated FDCs with built in data separators are not readily
>> available.
>>
>> Please remember, this is a *home brew* computer project -- a *real* Z80
>> running CP/M 2.2 on *real* hardware. It is what you make of it. If all you
>> want is a PC CP/M emulator then this project is not for you.
>>
>> Thanks and have a nice day!
>>
>> Andrew Lynch
>>
>>
>>
CP/M Z80 home brew computer circuit board
bfranchuk at jetnet.ab.ca bfranchuk at jetnet.ab.ca
<mailto:cctalk%40classiccmp.org?Subject=CP/M%20Z80%20home%20brew%20computer%
20circuit%20board&In-Reply-To=48546EA0.8000301%40pacbell.net>
Sat Jun 14 21:08:23 CDT 2008
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________________________________
Jim Battle wrote:
>
> Great, Ben! I look forward to seeing your design. Debug it, document
> it, put up a web page, build PCBs, and offer to sell them at cost and
> see how many grumbles you get.
>
Well when you think about it , I can down load a Z80 - CP/M emulator
that is just as fast and
I can read emulated disks from my PC. When I think CP/M I think floppy
disk and I think
you still can get the floppy disk controller chips.
-----REPLY-----
Hi! Thanks Jim for the comments. Please let me address the issues raised
by Ben:
If you look closely at the SBC design, you'll notice it has a feature even
better than a floppy controller -- it has a fully buffered IO bus! It
contains all the Z80 signals brought out to the DIN 41612 connector. The
peripheral bus adheres to the published ECB standard.
If you want floppy IO, the solution is simple -- just design one and attach
it to the bus! I have already done this with my Disk IO board (IDE and
NEC765 FDC) which plugs into my home brew ECB backplane along with the SBC.
Assuming there is enough interest in these home brew SBCs, I hope to make a
PCB version of the Disk IO board.
Yes, this SBC is a slightly modern variation of a vintage Z80 CP/M design.
I relaxed some of the traditions to make it affordable, reliable, and still
useful. The P112, while an excellent design and a wonderful SBC, costs $165
for a kit when it is available. I know of no other hobbyist Z80 projects
where one can purchase the PCB.
There are many Z80 designs available, however, without a PCB it means most
hobbyists will have to use temporary breadboards, wire wrap, or prototype
boards. None of those lend themselves to long term reliable solutions --
especially for a wide range of hobbyist builders.
The SBC PCB is meant to be *low cost* and the *common* element of a home
brew computer with *simple* IO. Adding unnecessary and complex IO
peripherals increases PCB area and cost, raises part count, and pushes away
the hobbyists it is meant for.
Selecting IO has to be done very carefully. Not everyone who builds this
SBC wants floppy IO. I have had numerous requests for many forms of IO
ranging from SCSI, IDE, floppy, CF, SD, USB, the Zilog peripherals, etc.
There is no solution which will satisfy everyone.
Implementing floppy IO can take on many variations and picking the FDC is
just the first of many challenges [FDC1793? NEC765? SMC9266? WD2797?]. What
about the data separator? Few chips remain and viable sources are scarce.
Even integrated FDCs with built in data separators are not readily
available.
Please remember, this is a *home brew* computer project -- a *real* Z80
running CP/M 2.2 on *real* hardware. It is what you make of it. If all you
want is a PC CP/M emulator then this project is not for you.
Thanks and have a nice day!
Andrew Lynch
Picked up what turned out to be a video card & monitor for a TI
Professional PC, thinking I might be able to use it in one of my old PCs
to experiment with one of the "also rans" of the early PC video card biz
:).
Unfortunately while it may be ISA compatible (is it?), the card is
longer than the standard "full length" and it won't fit into any of my
machines. No idea if it works, monitor powers up OK. If you want it,
it's yours. It's in the Seattle area.
Let me know,
Josh
Sounds too dang fishy....too many coincidences...
Sold on eBay, bought on eBay, relisted on eBay...
Oh - and both in Indiana, and HAPPEN to know each other?
Pictures of 2 auctions show same item, except the cassette adapter is washed out on
upper-right corner, where it was evident they tried to remove the word "homebrew" and whatever
else?
Doesn't have any idea on this stuff, and dropped nearly 4 large ($4K) on it?
I wouldn't buy an athlete's autograph for over $100 without some 3rd-party authentication, and he
drops $4K like that? Selling something as what it's not, such as that, is fraud, and being near $4000,
that's Grand Theft and a Felony in every state of our fair country - and he's not worried about losing $4K?
Oh, and his buddy "Mark" bought it from him for $1500? Dang - another coincidence - that seller (2nd one,
claiming it was real) HIS name happens to be Mark as well, as evidenced by his only current eBay listing,
where he answers a question, and putting "~Mark" at the end:
http://cgi.ebay.com/RARE-Apple-Computer-Freestyle-Tablet-PowerBook-Laptop_W…
Has no idea, no knowledge of the stuff, yet in the auction listing he says he hooked it all up and
tested it with an 'ACSII' <sic> keyboard? Come on - a n00b knowing nothing can do that?
In the listing, he says it was blown off because it had a thick layer of dust?
Hmm...I didn't see that on the FIRST listing...plus, didn't he claim it was in a display case, which was
supposedly available for local pickup?
Sorry - I don't buy it. Maybe I'm more cynical than most, but that whole string of cr at p is unbelievable.
I see too many similarities in completed auctions of BOTH of those eBay ID's.
He saw the first listing, saw the clone was local, he bought it, tried to scam it on fleaBay, and he got spanked in his attempt.
Thanks to the eagle-eyed honest folks out here, someone did NOT get ripped off.
Nice catch, guys!
Tony
-----Original Message-----
From: Evan Koblentz evan at snarc.net
Sent 6/15/2008 1:27:35 AM
To: 'General Discussion: On-Topic and Off-Topic Posts' cctalk at classiccmp.org
Subject: RE: (copy of ) Apple I on ebay
I traded some email tonight with the seller. His replies were interesting
so I asked if I could share them here on cctalk. He said yes.
----------------
In the first message he said (exact quote, unedited):
Well, I didn't want people getting something they don't want or expect,
thats not what I'm about. BTW after talking to my friend locally... The
whole story and truth came out about this computer! So, the guy (a long
close freind of mine ebay account MacEffects bought this from the seller
listed recently, and sold to a guy in a city about 20 miles away... I love
auctions, went to what I thought was an Estate auction... But it was a house
full of scams... And it was being offered as the real deal, and advertised
in local paper, sevral bidders, I won it for $3950 (a low price I thought,
but I didn't know of this Obtonic computer), and figured I'd make some money
being that I have no idea of these computers, or collect (serious) anyways,
I thought I'd sell it... Turns out, I got screwed, he won't take it back and
the cops are 'investigating' him for other things similar to it, anyways my
buddy in town Mark bought it for $1500 off me (he lost a little) but, its
better then nothing, he plans to sell it as well. I lost an additional $160
on eBay listings .. I tried going on your site, but I can't figure out the
Forum thing. Are you a member there? Anyways, thanks for helping me out I
appricate it, I got 30 e-mails in 6 hours, so I pulled it, the 4 'experts'
are wrong... pfft, happens, it fooled ME!
Then in a second message he said (again, unedited):
Yeah, its odd... The net makes it a small world, rarity that I ended up with
something a good friend and fellow "noob" collector, both had it, and not
directly. But life happens, anyways, yeah if you could just let them no, I
didn't try to scam anyone, as I pulled the auction within 1.5 days of being
listed, I don't want anyone to get screwed, it happened to me, but it sucks,
and I don't want someone else to go though it. Anyway if you'd let them know
that'd be nice, if not thats fine too. Just don't want a bad rep. Thanks
Again.
------------------
So there ya'll have it. According to this seller, he got fooled. At first
he heard from some self-proclaimed "Apple experts" (probably just fanboys)
insisting it is a REAL unit. Then he got a bunch of emails from we crazy
cctalk'ers who scared him into reality. :)
-----Original Message-----
From: Evan Koblentz [mailto:evan at snarc.net]
Sent: Saturday, June 14, 2008 11:01 PM
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: RE: (copy of ) Apple I on ebay
Yah, right - just so happened that he got busted trying to rip
people
off.
It appears, at least in my opinion, that the seller was merely uninformed
and/or in denial because HE got duped -- not trying to scam anyone.
Or at least that's what I want to believe ...
Well, I thought I'd chime in since I'm somewhat of an "expert" on these.
As has been thoroughly deduced already, the board in question was an
obvious fake. The lack of the copyright message, the font of the
lettering, the contour of the PCB traces, and the other more fine details
are all dead giveaways. It's obviously and Obtronix clone.
The fact that the definitive telltale marks have been washed from the
board is damning. I'm sure there's an interesting story behind this
either way.
With regards to the auction text:
"Trophy For 1st place 2002 Vintage Computer & Electronics Faire"
If the guy was talking about the Vintage Computer Festival then I don't
know what he's talking about. We didn't feature any Apple-1 in the
exhibits at VCF 5.0 in 2002.
Al said:
"I though Sellam knew where all of them were?"
I only know where the ones are that I know of :) I am discovering roughly
2 new ones out in the wild every year or so, though I expect that trend to
drop off sharply over time as I've already located 42 so far and my
research tells me that there are probably (PROBABLY) no more than 50 still
in existence. I emphasize "probably" because this number was deduced
through research that was not exacting (I can provide details if there's
interest).
I'm glad the guy had the sense to pull the auction.
--
Sellam Ismail Vintage Computer Festival
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> > Is anyone else questioning if this 'original' might instead be one of Steve
> Gabaly's
> > (aka 'obtronix') replicas?
>
>
> That appears to be the case. The Rockwell 40 pin chip is wrong as well.
>
> Unfortuantely, "counterfeits" doesn't appear to be in any of the categories
> eBay lets you report.
In taking a second look, the cassette board doesn't have a copyright message
(or NTI logo) because it too, appears to have been specifically altered to remove
Steve's 'Homebrew 2005' message.
What a shame...
Scott
