markb@tplrd.tpl.oz.au (Mark Bower) (05/07/91)
Using a 3.5" 1.44MB floppy drive in an A2000
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I recently posted a net-request for info pertaining to adding a non-amiga
floppy drive to the A2000. Thanks to all those who responded. Since then
I have made a small modification to the 1.44 MB drive which allows it to
be used wth most amiga software. In fact, it works with anything that uses
the trackdisk.device I/O handler, but some games (mainly copy protected ones)
don't seem to like it (they don' crash, they just don't recognise the disk in
the drive). Anyway, enough of this rambling, heres the modification:
Introduction:
~~~~~~~~~~~~~
This modification allows one to use an IBM type 3.5" 1.44 MB floppy disk drive
to be used in an amiga which will allow it to read standard AmigaDOS disks.
At this stage, this does not allow the amiga to have a High Density floppy
drive.
Procedure:
~~~~~~~~~
The drive used was a Chinon FZ357 (Revision A) 1.44 MB 3.5" High Density
floppy. However, the procedure given below is fairly generic and could be
applied to other drive types.
Disclaimer : I take no responsibility for anyone causing damage or injury to
either equipment or biological life while performing this procedure or while
reading this document(!).
o 1. Place the drive upsidedown on a flat surface.
o 2. Remove the (almost) rectangular protective shielding that covers
the circuit board that has the floppy drive connector, power supply
etc. This should be held on by a single screw at the side of the
drive.
There is no need to remove any other shielding or covers from the
drive.
o 3. This part of the procedure requires a small amount of soldering:
On the FZ357 Drive, locate Jumper J5. It is located at the
rear of the drive next to about 6 jumper pads thus:
----------------- Power Connector
|Floppy Conector| C J ||||
|is here | 3 6 Rear of drive. ||||
----------------- |*|*|*|*|
J5--| | | | |
|*|*|*|*| (may be more jumpers/capacitors)
|| to front of drive.
\/
NOTE: The silk screen on my drive didn't have J5 marked
very close to the actual jumper (it was about 8 mm away)
but there are no other jumpers close to it so there
shouldn'y be too much confusion.
At the moment, J5 should be OPEN (i.e. the two pads not connected
together). using a soldering iron and a small piece of tinned copper
wire (or as you see fit) connect the pads of jumper J5.
On (almost) any other drive :
Locate the jumper which connects to pin 2 (the CHNG line on the floppy
connector) of the floppy data cable connector. If you can find this
jumper (not all drives may have this), trace the other side of it
and see if it connects to the RDY line of the floppy connector (pin
34 of the floppy data cable connector). This jumper should be
bridged by wire and solder as for the FZ357 drive. (I recommend
using a digital multimeter/signal tracer to trace the signals
from the connector to the pins to ensure that you are connecting
the right signals together. (Maybe even a switch soldered across
the jumper so that you can test the drive while it is operating.)
o 4. Next, set the drive select jumper for the drive numbe you wish
to use this drive as. This can be selected via a set of jumpers
(usually) located at the rear or side of the drive. If you
have a floppy connector cable with a twisted section in it, then
you can select the drive to be 0 (the lowest drive number
is 1 in some drives).
o 5. Finally, on the A2000, connect a jumper socket over conector
C301 on the motherboard (located near where the floppy connector
cable connects to the motherboard. This allows the A2000 OS
to automatically mount the drive at boot time.
o NOTE : The power supply connector on some drives is reversed -
On the Chinon FZ357 it was not (I could connect it directly)
but on other drives please check this.
The drive should now read and write your amiga floppies like (almost) the
standard amiga drive.
Unresolved Issues:
~~~~~~~~~~~~~~~~~~
* Compatibility with some games. Anyone out there solved this
problem ith similar drives ?
* Has anyone had any success in using the High Density capability
of these type of drives ? I'll try to write a driver when I
get time but i'd rather not re-invent the wheel if someone
else has done it.
Cheers to all,
Mark.
| /\
------------------------------------------------------------|/ \ /-----------
Mark F. Bower. (markb@tplrd.tpl.oz.au) | \/
Telectronics Pacing Systems | "Waaaaaaa, Wahhhh, Wahhhhh, Waaa...."
R & D |
7 Sirius Rd. | The 'Baby' - Eraserhead.
Lane Cove 2066 |
-------------------------------------------------------------------------------cmcmanis@stpeter.Eng.Sun.COM (Chuck McManis) (05/20/91)
In article <1991May7.002625.1696@tplrd.tpl.oz.au> (Mark Bower) writes: >Unresolved Issues: >~~~~~~~~~~~~~~~~~~ > * Has anyone had any success in using the High Density capability > of these type of drives ? I'll try to write a driver when I > get time but i'd rather not re-invent the wheel if someone > else has done it. Nontechnical people shouldn't try things they don't understand. 1.44MB drives are that way because they use a 500KHz clocking frequency, the Amiga can only generate a 250Khz bit rate clock. Sorry you lose. Read up on disk electronics (good references are early issues of BYTE or Kilobaud Computing which talk about 8" floppies that also use 500khz bit clocks). Also note that the recording bias of the read/write head is different than it is for regular floppies (about 600 oresteads as opposed to 450 oresteads) any good text on magnetic recording will explain it to you. --Chuck -- --Chuck McManis Sun Microsystems uucp: {anywhere}!sun!cmcmanis BIX: <none> Internet: cmcmanis@Eng.Sun.COM These opinions are my own and no one elses, but you knew that didn't you. "I tell you this parrot is bleeding deceased!"
markb@tplrd.tpl.oz.au (Mark Bower) (05/21/91)
In article <13613@exodus.Eng.Sun.COM> cmcmanis@stpeter.Eng.Sun.COM (Chuck McManis) writes: >In article <1991May7.002625.1696@tplrd.tpl.oz.au> (Mark Bower) writes: >>Unresolved Issues: >>~~~~~~~~~~~~~~~~~~ >> * Has anyone had any success in using the High Density capability >> of these type of drives ? I'll try to write a driver when I >> get time but i'd rather not re-invent the wheel if someone >> else has done it. > >Nontechnical people shouldn't try things they don't understand. 1.44MB ^^^^^^^^^^^^^ People who reply to the net should not make rash assumptions about the technical background of net-users, its fair enough to make a technical correction, but its downright unethical to _personally_ flame someone you don't even know. To set the record straight, I'm an Electrical Engineer (Computer Systems) which I would hardly describe as non-technical :-) >drives are that way because they use a 500KHz clocking frequency, the >Amiga can only generate a 250Khz bit rate clock. Sorry you lose. Read >up on disk electronics (good references are early issues of BYTE or >Kilobaud Computing which talk about 8" floppies that also use 500khz [stuff deleted] Why can't I use an external buffer/500 kHz bit rate sync circuit? Thats what my 8 bit HD Floppy controller does thats sitting in my PC. Granted, it's more involved than simply plugging in a drive and using it but it's certainly not impossible. (Hope this reply doesn't appear twice - something happened to my editor) (the first time!. ) Mark /\ ------------------------------------------------------------|/ \ /----------- Mark F. Bower. (markb@tplrd.tpl.oz.au) | -Music == Life- \/ -808 State- Telectronics Pacing Systems R & D | UNIX 8*), PC :-(, and Amiga :-) user 7 Sirius Rd, Lane Cove 2066, |------------------------------------- Australia | Phone (Voice) <aust> 413 6913| Disclaimer: All opinions my own -------------------------------------------------------------------------------
kdarling@hobbes.catt.ncsu.edu (Kevin Darling) (05/23/91)
markb@tplrd.tpl.oz.au (Mark Bower) writes: > Why can't I use an external buffer/500 kHz bit rate sync circuit? Thats > what my 8 bit HD Floppy controller does thats sitting in my PC. Granted, > it's more involved than simply plugging in a drive and using it but it's > certainly not impossible. I thought there was a company selling HD floppies for the Amiga? Must mean it's possible (well heck, anything is possible as we all know! :) I'm no expert, but doesn't the Amiga floppy DMA only handle a couple of bytes per horz scan line? HD drives would output a byte every 32us, which doesn't leave enough slack, if my brain hasn't fried too much lately. Your idea of an external buffer sounds good. Or perhaps make a card with its own DMA circuit? regards - kevin <kdarling@catt.ncsu.edu>
kdarling@hobbes.catt.ncsu.edu (Kevin Darling) (05/23/91)
kdarling@hobbes.catt.ncsu.edu (Kevin Darling) writes: >I'm no expert, but doesn't the Amiga floppy DMA only handle a couple of >bytes per horz scan line? HD drives would output a byte every 32us, which >doesn't leave enough slack, if my brain hasn't fried too much lately. I think I meant 16us. sigh... it _did_ get fried. - kevin
<LEEK@QUCDN.QueensU.CA> (05/23/91)
In article <1991May21.025924.4583@tplrd.tpl.oz.au>, markb@tplrd.tpl.oz.au (Mark Bower) says: >Why can't I use an external buffer/500 kHz bit rate sync circuit? Thats >what my 8 bit HD Floppy controller does thats sitting in my PC. Granted, >it's more involved than simply plugging in a drive and using it but it's >certainly not impossible. > Sure. It might be slightly easier and cheaper to hook up a PC style floppy to the Amiga bus. Now the only problem is that the floppy controller chip have a very small buffer - 4 bytes (I think). On the PC there is a DMA channel servicing that. You'll have to be able to keep up with the data transfer... Since you are in Computer Engineering, I'll leave the PC interface as an exercise for the student. The ISA bus cycles are very similar to that of the Amiga bus cycles. With a little of glue logics, you should be able to get away with something that can talk to the floppy disk controller. -------- (Note: keyword 'get away' == not even close to 100% compatible, but works for this particular purposes on most configurations.) > >Mark > /\ >------------------------------------------------------------|/ \ >/----------- >Mark F. Bower. (markb@tplrd.tpl.oz.au) | -Music == Life- \/ -808 >State- >Telectronics Pacing Systems R & D | UNIX 8*), PC :-(, and Amiga :-) >user >7 Sirius Rd, Lane Cove 2066, >|------------------------------------- >Australia | Phone (Voice) <aust> 413 6913| Disclaimer: All opinions my own >------------------------------------------------------------------------------ >- K. C. Lee P.S. The above view do not represent this workstation nor its owner(s).
cmcmanis@stpeter.Eng.Sun.COM (Chuck McManis) (06/01/91)
[bad day I guess] I wrote : >Nontechnical people shouldn't try things they don't understand. 1.44MB In article <1991May21.025924.4583@tplrd.tpl.oz.au> (Mark Bower) replied: >People who reply to the net should not make rash assumptions about the >technical background of net-users, its fair enough to make a technical >correction, but its downright unethical to _personally_ flame someone you >don't even know. To set the record straight, I'm an Electrical Engineer >(Computer Systems) which I would hardly describe as non-technical :-) Ok if you're an Engineer how come you didn't either know this or know how to figure it out? Basic research 101 here, "How does a high density floppy work?" well there are lots of ways to find out, look at the schematics of your PC, read the data sheet on the floppy disk controller, maybe read the application notes for the chip (Western Digital used to have the best in my opinion) I tend to get rather less than tolerant of people who call themselves "technical" because they know how to assemble a PC clone from boards. You're an EE why don't you know this? >Why can't I use an external buffer/500 kHz bit rate sync circuit? Thats >what my 8 bit HD Floppy controller does thats sitting in my PC. Granted, >it's more involved than simply plugging in a drive and using it but it's >certainly not impossible. That's a good start Mark, your next question should be "how does the Amiga floppy controller work?" And the answer can be found by reading the technical documents available from Commodore (it can even be deduced by reading the schematic, hardware manual, and then disassembling the trackdisk code but only Germans seem to do that :-) And do you know how you PC floppy controller works? Presumably you have access to a chip distributor, they will usually _give_ you the data manuals for a particular chip family, often for every chip they make in the hopes that you will design them into their product. Anyway, the point to this response is as follows. Computers, and engineering are complicated disciplines. People go to school for 4 - 8 years to become Engineers (either hardware or software or both) and the purpose of that education is to teach them how to figure things out and design new and better things to meet the current requirements. Unfortunately, personal computers tend to attract a bunch of high school hackers that know enough about digital logic to be dangerous but not enough to understand what it is they are trying to do. (these are the folks that don't believe you when you tell them that hooking up a VGA monitor to an Amiga won't give you any more colors or resolution than their old monitor did (unless their old monitor was monochrome ;-))) Anyway, the net has become full of these folks who get everyone fired up because they make it sound like they've _almost_ got something wonderful to happen, if they could just get that missing piece of info. A few years ago it was clock speed doublers. Now along comes your article about 3.5" disk drives making it sound like everything is working with those 1.44MB drives except you just can't get them into "high density" mode. And everyone jumps up and says "Yeah, I want those HD floppies too, and gee Mark almost has them up and running. Commodore, why can't you put those in standard?" When, in fact, to get them into "high density" mode you have to redesign the floppy interface including new drivers, a memory/bus interface, etc. And yet no one to date has ever posted a question like yours and followed it up with exactly what it takes to do it. Why don't you just get a SCSI to floppy converter. Then at least all you would have to do is write the software. Sure its a flame, but wouldn't it be nice if someone actually did some of the work and _then_ posted the article? Sorry to be so long winded, and I apologize for flaming Mark without first ascertaining that he didn't understand the answer. -- --Chuck McManis Sun Microsystems uucp: {anywhere}!sun!cmcmanis BIX: <none> Internet: cmcmanis@Eng.Sun.COM These opinions are my own and no one elses, but you knew that didn't you. "I tell you this parrot is bleeding deceased!"
tomb@hplsla.HP.COM (Tom Bruhns) (06/04/91)
cmcmanis@stpeter.Eng.Sun.COM (Chuck McManis) writes: > When, in fact, to get them into "high density" mode you have to > redesign the floppy interface including new drivers, a memory/bus > interface, etc. And yet no one to date has ever posted a question > like yours and followed it up with exactly what it takes to do it. So what's wrong with posting to find out if anyone has indeed done it before (or maybe even just given it some serious thought)? Not everyone posts about each and every success, and even if they did, I wouldn't have time to read them all, and I don't have a good enough memory to remember them all. Also, why assume that "new drivers, a memory/bus interface, etc." are required? If the HD floppy external electronics makes it look like a standard 1-meg floppy (same data rate and format), but with more tracks, would the Amiga care (given the apropriate mountlist entry)? If I built a solid-state external 'floppy', would the Amiga OS even care how many tracks it had? BTW, a good source of floppy info from 'the old days' is some issues of Pertec's "Peripheral Review." I wrote a white paper for one of my classes (long ago) on feasibility of a certain floppy interface, and data from Byte's articles and from floppy drive manufacturers could not have let me make the case I did; the short Peripheral Review articles were packed with useful data on what really goes on in a floppy interface. I think they've been out of business for some time, but some old-timer (1970's ;-) may have copies. (These were little 4-8 page newsletters published occasionally...some sales articles and some technical) PS: Why would someone designing an interface to a stock floppy drive care about the flux density at the medium?
<LEEK@QUCDN.QueensU.CA> (06/04/91)
In article <18730003@hplsla.HP.COM>, tomb@hplsla.HP.COM (Tom Bruhns) says: > >Also, why assume that "new drivers, a memory/bus interface, etc." >are required? If the HD floppy external electronics makes it >look like a standard 1-meg floppy (same data rate and format), but ------ !!! >with more tracks, would the Amiga care (given the apropriate mountlist >entry)? If I built a solid-state external 'floppy', would the Amiga >OS even care how many tracks it had? > Well... The easiest way to hack is to slap a PC/XT style floppy disk inteface onto the expansion bus. In order to remap the High Density floppies to the same data format and different # of tracks, you would need some sort of microprocessor onboard to provide the smarts. I guess you'll also need a floppy controller chip that do the same type of arbitrary format as the Amiga one to talk to the Amiga floppy interface. It might be easier to build a black box to buffer the raw data bits at different clock rates between the Amiga & your HD floppy. A modified trackdisk device has to be able to handle the extra track length. > >PS: Why would someone designing an interface to a stock floppy drive >care about the flux density at the medium? K. C. Lee P.S. Why would someone wanting to design an HD floppy interface when C= already have one for the A3000 ?
jms@vanth.UUCP (Jim Shaffer) (06/07/91)
In article <91155.095422LEEK@QUCDN.QueensU.CA> LEEK@QUCDN.QueensU.CA writes: > >P.S. Why would someone wanting to design an HD floppy interface when C= > already have one for the A3000 ? When will it be available? -- * From the disk of: | jms@vanth.uucp | "You know I never knew Jim Shaffer, Jr. | amix.commodore.com!vanth!jms | that it could be so 37 Brook Street | uunet!cbmvax!amix!vanth!jms | strange..." Montgomery, PA 17752 | 72750.2335@compuserve.com | (R.E.M.)