david@ms.uky.edu (David Herron -- One of the vertebrae) (06/08/88)
In article <213@toylnd.UUCP> dca@toylnd.UUCP (David C. Albrecht) writes: >Just thought maybe some other people might be >interested in this feasibility study. Now I'm going to have to figure >out how to hook it up so I can switch between the 5 1/4 and the 3 1/2 >(visions of 36 pin centronics switch boxes dancing in my head). Getting the >distribution disks on 31/2s could be challenging. Ah well, future food for >thought. well well well. I've got all the parts together here to do this project and have been meaning to but never got around to actually doing it. I've got something a little different planned. I have a case & power supply for 2 half-height disks. I also have a 3.5" disk kit from tigertronics for making it look like a 5 1/4" drive. I'm planning on putting both drives into that case, run a cable from inside the machine to the drives, and put in a toggle switch of some sort for the power only. When I need to use the 5 1/4 I power it up, otherwise I power the 3 1/2. How does that sound? I'm glad to know it worked out for you.. -- <---- David Herron -- The E-Mail guy <david@ms.uky.edu> <---- s.k.a.: David le casse\*' {rutgers,uunet}!ukma!david, david@UKMA.BITNET <---- <---- [This space for rent].
dat@noao.arizona.edu (D'Anne Thompson) (06/09/88)
From article <9595@g.ms.uky.edu>, by david@ms.uky.edu (David Herron -- One of the vertebrae): > In article <213@toylnd.UUCP> dca@toylnd.UUCP (David C. Albrecht) writes: >>Just thought maybe some other people might be >>interested in this feasibility study. Now I'm going to have to figure >>out how to hook it up so I can switch between the 5 1/4 and the 3 1/2 >>(visions of 36 pin centronics switch boxes dancing in my head). Getting the >>distribution disks on 31/2s could be challenging. Ah well, future food for >>thought. > > I've got something a little different planned. I have a case & power > supply for 2 half-height disks. I also have a 3.5" disk kit from > tigertronics for making it look like a 5 1/4" drive. I'm planning > on putting both drives into that case, run a cable from inside the > machine to the drives, and put in a toggle switch of some sort for the > power only. When I need to use the 5 1/4 I power it up, otherwise > I power the 3 1/2. > > How does that sound? > Well, Why not try this ? Parallel cable from the Unix-PC to all drives. Between the Unix-PC and the first disk, cut the 4 drive select lines (DS0, DS1, DS2, and DS3) and install a two-way, three-way, or four-way switch to route DS0 (coming from the Unix-PC) to DS0, DS1, DS2, and DS3 going towards the disk drives. Install pull-ups (pull-downs) so the unconnected DSx lines are not unterminated (May not be necessary. Would have to check). I would be concerned about having an unpowered disk drive on the bus cable while another drive was running. The Motor logic line (xx?) would turn on/off the selected drive motor as necessary, but both drive interface boards would be powered up. How does that sound ? D'Anne Thompson dat@noao.arizona.edu National Optical Astronomy Observatories. Tucson, Arizona
richard@islenet.UUCP (Richard Foulk) (06/09/88)
} I've got something a little different planned. I have a case & power } supply for 2 half-height disks. I also have a 3.5" disk kit from } tigertronics for making it look like a 5 1/4" drive. I'm planning } on putting both drives into that case, run a cable from inside the } machine to the drives, and put in a toggle switch of some sort for the } power only. When I need to use the 5 1/4 I power it up, otherwise } I power the 3 1/2. } } How does that sound? Sounds like a good idea. You might want to toggle the drive select line along with the power. All the other lines should buss together okay. -- Richard Foulk ...{vortex,ihnp4}!islenet!richard Honolulu, Hawaii
adh@anumb.UUCP (a.d.hay) (06/09/88)
In article <213@toylnd.UUCP> dca@toylnd.UUCP (David C. Albrecht) writes: >Being an inveterate hacker, I've been at it again. I wondered if the 7300 >could take a 3 1/2" drive since it would make backing up somewhat more >pleasant and I already use an Amiga so have a supply of the little suckers >on hand. They do seem to cost more per MB unfortunately. Therefore, when >I saw the sale that good 'ol Radio Shack had on an external 31/2" drive for >their 1000HX system (for $99, it should still be on), I sprang into action >and got one. in this month's byte, computer warehouse has the teac 55G 1.6Mb 5.25" drive on sale for $89. the orig. drive is a teac 55B. [ deletions ] > Alligatored in the >appropriate power lines and tried it. No smoke but it didn't work. Noticing >that the 5 1/4" was selected to D0 while the 3 1/2" was D1, I changed it. >Voila! It formatted. > [ deletions ] > Tried formatting a disk with 10 >sectors/cyl ala. some of the 5 1/4" distribution disks, uh uh, no good, hangs >in formatting. 3.5" & 5.25" QD disks spin at 360 rpm like an 8" floppy, instead of 300 rpm. > Now I'm going to have to figure >out how to hook it up so I can switch between the 5 1/4 and the 3 1/2 >(visions of 36 pin centronics switch boxes dancing in my head). all you have to switch is the drive select line! [ deletions ] > >David Albrecht i've just spent last night scrutinizing the hardware reference manual, to see if it's possible to modify the FD controller to handle QD drives. if you don't mind losing backward compatibility, it can be done with the addition of only 1 chip. you have to double the clock to the 2797, and there's no 2MHz on the board. so, divide the 20MHz by 10.(this is the added chip) the 2793 has a clock divide select pin, to make mixing 5.25" & 8" drives easy. unfortunately, the 2797 replaces this with a side-select output and the clock select (transmit side) isn't tied to the 5"/8" select (receive side) input. after all this, you might have to re-adjust the trimmers around the 2797 for the new data rate. there are setups for ms-d*s that permit 1.2Mb drives to read and write 360K floppies. for the unix-pc, this would require rewriting the driver software which is embedded in the kernel and adding some logic. this would be tough if you couldn't get at the kernel src. ( though if you could, you could easily add logic to allow 4 floppy drives and 4 16-head hard drives at the same time! ) however, this would allow us to replace our internal drives with a QD drive without sacrificing compatibility. --------------------------------------------------------------- i'm investigating qic-40 tape drives with sa-450 (floppy) interfaces with an eye toward finding one that only needs an iv file to work in the unix-pc in place of the floppy drive. these drives are 40 Mb and use dc2000 cartriges. mountain has one that's selling for $380... -- Andrew Hay +------------------------------------------------------+ Lunatic By Birth | "Don`t try to out-wierd ME, three-eyes!" | AT&T-BL Ward Hill MA | I can't be bought, but I can be had... | ihnp4!mvuxq!adh +------------------------------------------------------+
edward@engr.uky.edu (Edward C. Bennett) (06/09/88)
In article <213@toylnd.UUCP> dca@toylnd.UUCP (David C. Albrecht) writes:
]I wondered if the 7300 >could take a 3 1/2" drive...
]
]Stress test time. Formatted it like a 5 1/4", no problem. Copied an FD entry
]from /usr/lib/iv and doubled the number of cylinders, formatted again no
]problem. Mounted it and copied files till it was full, then tried to use some
]of the last copied files, no problem.
Yes, but how much data could you put on the 3.5" disks? Unless it's
substantially more than what we get on 5.25" disk (360K?), this
whole conversion is little more than a novelty.
--
Edward C. Bennett DOMAIN: edward@engr.uky.edu
(606) 257-4938 UUCP: {cbosgd|uunet}!ukma!ukecc!edward
"Goodnight M.A." BITNET: edward%ukecc.uucp@ukma
"He's become a growling, snarling mass of white-hot canine terror"ford@elgar.UUCP (Mike "Ford" Ditto) (06/11/88)
In article <213@toylnd.UUCP> dca@toylnd.UUCP (David C. Albrecht) writes: > Tried formatting a disk with 10 >sectors/cyl ala. some of the 5 1/4" distribution disks, uh uh, no good, hangs >in formatting. Bummer. And strange, too, since the 3.5" drives are actually spec'ed at 800K, while the 5.25's are only rated at 360. > Now I'm going to have to figure >out how to hook it up so I can switch between the 5 1/4 and the 3 1/2 >(visions of 36 pin centronics switch boxes dancing in my head). Only the drive-select signal would have to be switched (that's what it's there for), the other 33 pins can be daisy-chained to all floppy drives. The floppy driver chips should be able to handle two drives with no problem at all, maybe even four drives. But you'll always have to manually flip the switch, so only one can be in use (open) at a time. -=] Ford [=- "Once there were parking lots, (In Real Life: Mike Ditto) now it's a peaceful oasis. ford%kenobi@crash.CTS.COM This was a Pizza Hut, ...!sdcsvax!crash!kenobi!ford now it's all covered with daisies." -- Talking Heads
thad@cup.portal.com (06/11/88)
3.5" drives have the following capacities: Amiga 880K Atari 720K Mac 800K PS2 720K (or 1.4MB if quad density) The quad density 5-1/4" disks: C64 1.05MB IBM PC/AT 1.2MB
lenny@icus.UUCP (Lenny Tropiano) (06/12/88)
In article <2422@ukecc.engr.uky.edu> edward@engr.uky.edu (Edward C. Bennett) writes: |>In article <213@toylnd.UUCP> dca@toylnd.UUCP (David C. Albrecht) writes: |>]I wondered if the 7300 >could take a 3 1/2" drive... |>] |>]Stress test time. Formatted it like a 5 1/4", no problem. Copied an FD |>]entry from /usr/lib/iv and doubled the number of cylinders, formatted |>]again no problem. Mounted it and copied files till it was full, then |>]tried to use some of the last copied files, no problem. |> |>Yes, but how much data could you put on the 3.5" disks? Unless it's |>substantially more than what we get on 5.25" disk (360K?), this |>whole conversion is little more than a novelty. If he doubled the amount of cylinders as in says in his article (see above quoted section) that means you will get double the space... about 720K. -Lenny BTW: You have to realize that 3.5" disks cost about twice as much as 5.25" ones... so you'll get twice the space at twice the costs... One wonders how much savings that is.. (Other than you sanity for inserting and removing disks) -- US MAIL : Lenny Tropiano, ICUS Computer Group IIIII CCC U U SSS PO Box 1 I C U U S Islip Terrace, New York 11752 I C U U SS PHONE : (516) 968-8576 [H] (516) 582-5525 [W] I C U U S TELEX : 154232428 [ICUS] IIIII CCC UUU SSS AT&T MAIL: ...attmail!icus!lenny UUCP : ...{talcott, boulder, pacbell, sbcs, mtune, bc-cis}!icus!lenny
richard@uhccux.uhcc.hawaii.edu (Richard Foulk) (06/13/88)
}If he doubled the amount of cylinders as in says in his article (see above }quoted section) that means you will get double the space... about 720K. } }-Lenny } }BTW: You have to realize that 3.5" disks cost about twice as much as 5.25" } ones... so you'll get twice the space at twice the costs... One wonders } how much savings that is.. (Other than you sanity for inserting and } removing disks) Reducing the pain of backing the system up is what it's all about. I'm still waiting for an affordable tape system. But a simple doubling of diskette capacity is real tempting. Also, I think 3.5" disks have been found to be more reliable. Some time back someone posted an article about having installed a 3.5" drive on their unixpc and explained all about, including the configuration files. Perhaps someone could pull it out of the archives and repost it. Richard
lenny@icus.UUCP (Lenny Tropiano) (06/15/88)
In article <1944@uhccux.uhcc.hawaii.edu> richard@uhccux.UUCP (Richard Foulk) writes: |>}If he doubled the amount of cylinders as in says in his article (see above |>}quoted section) that means you will get double the space... about 720K. |>} |>}-Lenny |>} |>}BTW: You have to realize that 3.5" disks cost about twice as much as 5.25" |>} ones... so you'll get twice the space at twice the costs... One wonders |>} how much savings that is.. (Other than you sanity for inserting and |>} removing disks) |> |>Reducing the pain of backing the system up is what it's all about. |>I'm still waiting for an affordable tape system. But a simple |>doubling of diskette capacity is real tempting. |> |>Also, I think 3.5" disks have been found to be more reliable. |> |>Some time back someone posted an article about having installed a |>3.5" drive on their unixpc and explained all about, including the |>configuration files. Perhaps someone could pull it out of the |>archives and repost it. |> |>Richard Here's the article that started this whole discussion... there weren't any configuration files, but it should be as easy as: #sccs "@(#)iv:fdfmt-mini.nl 1.1" iv -i /dev/rfp020 /usr/lib/iv/FDnl-mini mkfs /dev/fp021 dismount -f > /dev/null 2>&1 --- /usr/lib/iv/FDnl-mini: #sccs "@(#)iv/lib:FDnl-mini 1.1" type FD name Floppy cylinders 80 heads 2 sectors 8 steprate 0 singledensity $ $ $ 0 1 $ $ -- Original article follows: |Article 2802 of comp.sys.att: |Path: icus!mtune!codas!peora!ge-dab!ge-rtp!edison!toylnd!dca |>From: dca@toylnd.UUCP (David C. Albrecht) |Newsgroups: comp.sys.att |Subject: 3 1/2" on the 7300 |Message-ID: <213@toylnd.UUCP> |Date: 28 May 88 03:01:07 GMT |Distribution: na |Organization: Dave & Anne in Charlottesville, VA |Lines: 45 | |Being an inveterate hacker, I've been at it again. I wondered if the 7300 |could take a 3 1/2" drive since it would make backing up somewhat more |pleasant and I already use an Amiga so have a supply of the little suckers |on hand. They do seem to cost more per MB unfortunately. Therefore, when |I saw the sale that good 'ol Radio Shack had on an external 31/2" drive for |their 1000HX system (for $99, it should still be on), I sprang into action |and got one. | |The cable coming out of the thing appeared useless. Prying |it apart the drive instide has a connector on the drive which is the same as |the one coming off the 7300 motherboard. It has a power connector which is a |different size than the one on the 5 1/4 inside the 7300 but same stuff |5v, 12v, 2 GNDs. Inside the 3 1/2 drive box there is a pc board which |converts the cable from the drive and power lines to go out the cable |from the box. I clipped the ribbon cable off at the pc board and stuck a 34 |pin connector on it (again from radio shack). Then, I clipped the power lines |at the pc board in preparation for an alligator to 5 1/4" power line connection |job. I then dug the 7300 I have for spare parts out of the box its in |(I'm not crazy enough to do this on the 3b1 I use all the time). Unplugged the |5 1/4" from the motherboard and plugged in the 3 1/2". Alligatored in the |appropriate power lines and tried it. No smoke but it didn't work. Noticing |that the 5 1/4" was selected to D0 while the 3 1/2" was D1, I changed it. |Voila! It formatted. | |Stress test time. Formatted it like a 5 1/4", no problem. Copied an FD entry |from /usr/lib/iv and doubled the number of cylinders, formatted again no |problem. Mounted it and copied files till it was full, then tried to use some |of the last copied files, no problem. Tried formatting a disk with 10 |sectors/cyl ala. some of the 5 1/4" distribution disks, uh uh, no good, hangs |in formatting. Oh well, I guess you can't have everything. Don't know if you |can format it as a 720K MSDOS disk. | |Just thought maybe some other people might be |interested in this feasibility study. Now I'm going to have to figure |out how to hook it up so I can switch between the 5 1/4 and the 3 1/2 |(visions of 36 pin centronics switch boxes dancing in my head). Getting the |distribution disks on 31/2s could be challenging. Ah well, future food for |thought. | |Warning. This project is not recommended for those not well versed in the ins |and outs of cabling and the insides of PCs. I will certainly not be held |responsible for you mucking around inside your 7300/3b1. | | |David Albrecht | -- US MAIL : Lenny Tropiano, ICUS Software Systems IIIII CCC U U SSS PO Box 1 I C U U S Islip Terrace, New York 11752 I C U U SS PHONE : (516) 968-8576 [H] (516) 582-5525 [W] I C U U S TELEX : 154232428 [ICUS] IIIII CCC UUU SSS AT&T MAIL: ...attmail!icus!lenny UUCP : ...{talcott, boulder, pacbell, sbcs, mtune, bc-cis}!icus!lenny