>From: "Patrick Finnegan" <pat at computer-refuge.org>
>
>
>Not to discourage you, but, I'd echo the sentiment above. I'd suggest
>that if you do want to produce something, make something that can read
>the disk on a flux-transition level, and store that sort of data.
>Something nice and generic. That way, you can do all the processing in
>software, and handle any format of disk that comes your way.
>
Hi
I've always had in the back of my mind, the thought of
building something to capture the raw flux-transitions.
I still think the easiest way is to use the SPI port of
a DSP, like the 2181 or similar. These processors are
quite fast and can post process the raw data into something
that can be transferred to the host processor in a more
condensed and slower rate.
To keep Ethan happy, he could even used one of the old
modem cards made by Digicom and Cardinal that have 2115
and 2111 processors on them. A few hardware hacks and
it could be a disk data processor. These two modems,
called soft modems can have the entire software loaded
>from a PC.
For those that don't have one of these older boards, a
2181 development board might be the way to go. It makes
sense to keep the back disk controls from something simple
like the parallel port and just use the DSP for the
read/write of data.
The advantage of such a system is that the part count is
minimal. The 2181 has all of its RAM inside. It can bootstrap
>from a 8 bit EPROM or FLASH. One can connect up a simple
parallel or serial to a host PC. It can sample really fast.
For those that really need it, it can be programmed in "C"
( although the assembly is very clean ). The entire unit
can be done in less than 10 IC's.
There are distinct advantages to keeping the data processor
separate from the host. One doesn't need to be concerned
with how to handle other system level interrupts. One
can buffer the data for safer transfer rates to the
host system's mass storage.
One thought, although the CatWeasel used sample rates on
the order of 40MHz, adding a simple flopflop to the input
significantly reduces the sampling rate needed( as I've
stated before ).
Dwight
> Why hasn't somebody done an open catweasel?
It's a pretty teeny market (other than the forensics possibilites).
I keep wondering why COPY II Plus cards go for so much on eBay.
Brad's suggestion of using an ARM with FPGA (or something
>from Mesa Engineering) could certainly be done.
If you define a protocol, doesn't really matter what it's
implemented with (my personal preference would be something
with enough horsepower that it could just sit on an ethernet)
> Speaking of which: are there other people out there who collect
> development hardware?
I do.
Development systems:
Tek 8002A, 85x0's
Some for the HP 64000 (would like to get a simulator for this running
some day). Some docs on bitsavers, no software.
Millennium 9520
In-circuit emulators:
various Applied Microsystems
various Huntsville Microsystems
various Microtek MICE
and various Gould and HP logic analyzers (fav is HP 16500B)
And, as usual, the hardware is fairly easy to find and documentation
and software nearly impossible.
As companies stop using uP's, they toss the development equipment.
The iron shows up, but not the sw or manuals.
>From: "Scott Stevens" <chenmel at earthlink.net>
>
>On Tue, 2 Aug 2005 01:19:52 -0400
>"'Computer Collector Newsletter'" <news at computercollector.com> wrote:
>
>> Regarding the "first" PC specifically, Doug Salot explains it quite
>> well: http://www.blinkenlights.com/pc.shtml
>>
>> -----Original Message-----
>> From: cctalk-bounces at classiccmp.org
>> [mailto:cctalk-bounces at classiccmp.org] On Behalf Of steve
>> Sent: Tuesday, August 02, 2005 1:11 AM
>> To: General Discussion: On-Topic and Off-Topic Posts
>> Subject: Re: Kenbak-1 on Ebay
>>
>> I don't think you can ever claim any computer as the first one without
>> some qualifications(computer using relays, tubes, TTL, microprocessor
>> etc), I think in the 1950's a relay computer kit called Simon was
>> available from Radio Electronics.
>>
>> For microprocessor based computers the original manufacturer always
>> made the first computers based on their processor (so if you assume
>> the 4004 was the first microprocessor then Intel Intellec or its
>> single board cousin Sim-4 could be considered the first microprocessor
>> based computers).
>>
>
>Well, Intel didn't originally really intend the 4004 to be the basis of
>a general purpose programmable computer. I suppose their early
>development hardware can be considered a 'personal computer' kinda
>sorta.
>
>Speaking of which: are there other people out there who collect
>development hardware? I have an assortment of 'development systems' all
>the way from the little cheap 'evaluation kit' boards to my MDS system
>with 8051 hardware ICE. (I also have the Intel 'bubble memory
>development kit' which includes bubble memory on an ISA card, docs and
>'sample' drivers to make it a small DOS non-volatile memory, which is
>probably one of the more rare Intel 'Development Kits') I grab up
>emulators and what-not where I can get them, like I got another 68HC11
>emulator and a 68HC16 at the last IUPUI auction for five bucks each
>(complete in-the-box with everything).
>
Hi
I do have a few items but don't specifically go out to find
such things. I have a working SIM4-01, a i2920 development
board ( analog processor, not bit slice ). MDS800, SDK85, SDK86,
Z80 ICE for multibus and a ICE for 6502 ( standalone ). I have
several small developement boards such as SYM-1, EZDSP2181 and
a 80188 board. I also have several Intel SBC boards for 8080's
of different versions.
So, yes, there are a number of us that have such things.
Dwight
> Is there anything the WD chip won't handle versus a raw track
approach?
Any format not derived from the IBM SD and DD standards.
- HP 300
- DEC RX02
- TI FD1000
- INTEL M2FM DD
- AED 2500 and 6200
- AED WINC05 5"
Eric and I built a sampling reader as you suggested a while back.
I would suggest storing deltas between transitions, measured at a
much higher rate (from memory, Catweasel can delta at up to 40MHz
resolution)
>
>Subject: Re: Another disk imaging project
> From: Dave Dunfield <dave04a at dunfield.com>
> Date: Wed, 03 Aug 2005 10:53:11 -0400
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>>Finally, is the WD2793 able to read northstar horizon floppy disks? If not,
>>then a WD2793-based solution is not general enough.
No, the NS* hard sector format done not use or encode all the marks used by
most FDC chips.
The upside of NS* is that a simple data seperator and a shift register are
all thats needed to read it (look at the board schematics). Most fo the
board is centered on getting the data rate down to something an 8080 can
handle. Data bit rates for NS* are 125 and 250kb/s so it's very slow
relative to what most newer machines can do.
Allison
Thanks everyone for their help with the Analog phone line/modem/pbx/term
server/etc question I had! Really helpful!!
I've got a few different ways to go about it now. I think I'll keep an eye
out for a small analog PBX...again, I'm locked to the analog modems on my
target system - it's an older machine and the software isn't adjustable for
other modems, nor does it have the capability to add multiple serial ports to
go with external modems. Even if I could get multiple serial ports, I'm
working with software that lets me chose 1 of two brands of internal modem...
Without reworking the code, which i'm in no way a programmer, would quite an
undertaking right now..
My first step is tracking down a Term server that would translate the
internet telnet requests to trigger a DTR drop, which will in turn trigger
the external modem to dial out....OR....incorporating the analog modem into
the term server to dial out without needing external modems and cables. This
is all through "reverse telnet" from what I gathered? Does anyone have any
suggestions of models? The Portmaster 2 or 2e sounded like a possibility...
not sure if there were others, or perhaps instead of the external modems
there was a cheap modem bank system out there, so I could tie the term server
to the modem bank, and the modem bank would have analog lines coming out of
it that would go to my PBX?
Pete
Hi Allison,
>>Unfortunately it's looking like mixed sector sizes within one track are
>>not within the capabilities of the 765 to write - although I could probably
>>READ them OK (and with a documented image file format, you would at least
>>have access to the data so you could try to find some other way to recreate
>>the disks if you had to).
>
>Dave there is a trick.
>
>Looks at FCOPY at Gaby's (unoffical CPM archive). Tim and I developed it
>for a project and it's not a generic imager. However we found a few things
>out and one is that most 765 implmentations will lock up if in the worng
>mode (SD or DD) initially. So to do mixed sector you can't write. However
>reading is possible if you first try the mode that doesnt lock first then
>switch.
Thanks for the info - I'll check it out when I make the changes to support
mixed density reading ... (which may be a while).
>In the end you will be recreating the catsweasel. If you really want to
>go to the next level starty with a PC fast enough and skip the whole FDC
>chip thing. The next level is a data speperator logic and a shift
>register that can be read at the bit rate by the PC and do the needed
>pattern regognition (look for sync, address marks and the like), and then
>build a literally imaged disk and that can be anaylysed.
I've thought about this - I can do 500khz samples on a PC parallel port,
and with some simple hardware I could get 8x this - but it seems dodgey,
and unless I disable all interrupts (which has it's own set of problems
including losing HD access) there would be excessive real-time jitter.
I've also thought about dropping in something line a 90Mhz (or faster)
ARM - which would give me a much higher sampling speed and better real-
time control than a PC ... but this gets tough to build...
The 2793 would be easy to build, and should handle most soft-sector disks.
The "read track" and "write track" functions of the WD chip allow near raw-
access to the track data.
But these questions are part of the reason I've not done anything toward
a hardware solution so far.
Regards,
Dave
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.parse.com/~ddunfield/museum/index.html
Reason I ask is that I just had a look under Linux and it's possible (at
least with 2.6 kernels - no idea about earlier) to setup the FDC from
user-land via the fd floppy device.
--
And there is code to do make floppy images with this
http://dmklib.brouhaha.com
Probably needs to be some code to go between dmk and teledisk, since
dmklib is currently read-only.
