dannie@coplex.uucp (Dannie Gregoire) (02/13/91)
I have been trying to find some information on the hardware differences between 720K and 1.44M floppies. Specifically, what are the differences in the pin outs (and signals sent to the PC) between the drive's connectors. What signal (if any) is sent to the PC when the drive detects that a high densisty has been inserted.
cirian@einstein.eds.com (Steve Cirian) (02/16/91)
In article <1991Feb12.215709.17456@coplex.uucp>, dannie@coplex.uucp (Dannie Gregoire) writes: > I have been trying to find some information on the hardware differences > between 720K and 1.44M floppies. Specifically, what are the differences > in the pin outs (and signals sent to the PC) between the drive's connectors. > > What signal (if any) is sent to the PC when the drive detects that a high > densisty has been inserted. As far as I know, the pinouts would be the same. The way the computer knows what density the drive supports is through the BIOS setup. The 1.44 MB drives also support 720K, but I am not sure which pin the signal would be sent on when the drive senses a high density or low density floppy. I am sure this has been covered in this group before, but I am relatively new to it, so please forgive me if it has: It is possible to use a low density floppy in a high density drive, if you punch a hole in the appropriate place. I have seen advertisements for a device that will punch a hole in your floppy to enable it to be written to at the higher density, I don't know if I would trust floppies so modified with mission-critical data. The media IS different.) Steve Cirian -- ___ ___ ___ > Electronic Data Systems > Steve Cirian, Systems Engineer /___ / | /__ > 750 Tower Drive > cirian@einstein.eds.com /___ /__/ ___/ > Troy, Michigan 48007 > ...uunet!edsews!einstein!cirian >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
mamos@uafhp.uark.edu (Mark _E_ Amos) (02/17/91)
cirian@einstein.eds.com (Steve Cirian) writes: >it, so please forgive me if it has: It is possible to use a low density floppy >in a high density drive, if you punch a hole in the appropriate place. I have >seen advertisements for a device that will punch a hole in your floppy to >enable it to be written to at the higher density, I don't know if I would >trust floppies so modified with mission-critical data. The media IS different.) Excuse me if I am out of line, as I don't know for sure, but I have noticed many 3.5" "low-density" (720K) disks have a max rating of 1.5Meg either stamped on them or on the package. Mind you, this was back BEFORE the 1.44 drive came out... I also believe the "High Density" (1.44M) disks are rated at 2.0 Meg. Can anyone concur? Or have I seen wierd floppies with these numbers, usually on the little metal door (the flibbit)... ============================================================================== Mark _E_ Amos | University of Arkansas Computer Science Engineering mamos@uafhp.uark.edu | mea1@engr.uark.edu | (emphasise the Computer Engineering please) ------------------------------------------------------------------------------ "Man's mind, when stretched to a new idea, never goes back to its original dimension." -Oliver Wendell Holmes ==============================================================================
torvalds@cc.helsinki.fi (02/17/91)
> In article <1991Feb12.215709.17456@coplex.uucp>, dannie@coplex.uucp (Dannie Gregoire) writes: >> I have been trying to find some information on the hardware differences >> between 720K and 1.44M floppies. Specifically, what are the differences >> in the pin outs (and signals sent to the PC) between the drive's connectors. >> >> What signal (if any) is sent to the PC when the drive detects that a high >> densisty has been inserted. Right, this info is straight from the EPSON SMD-340 3.5" floppy drive manual (not guaranteed, but should of course work for others as well :-) Pin Name what? 2 HDI High density in (low in 2MB mode (2MB unformatted=1.44MB)) 4 NC 6 DS3 Drive select 3 (low -> selected) 8 IDX* Index 10 DS0 Drive select 0 12 DS1 Drive select 1 14 DS2 Drive select 2 16 MON Motor on (low - on) 18 DRTN Direction (low - step inwards) 20 STP step (transition low->high steps motor, usuallu 3 ms) 22 WTD Write data 24 WTG Write gate (active low) 26 TK00* Track 0 (low means we are on track 0) 28 WPT* Write protect (low means write protected) 30 RDD* Read data 32 SSL Side select (note low means side 1, high means side 0) 34 DCH* Disk change pins 1,3,5 not connected, others grounded. * means signal from disk drive, otherwise to drive unit. NOTE! The HDI is not from drive to computer but the other way around. This can force the drive to use 2MB mode (1.44MB). This is in fact not used on most drives to my knowledge, as the drive senses the density from the disk covering. This can be enabled by a jumper on my drives. There are drives available that use pin 2 as HDO (High density out) to let the computer sense the density used, but I wouldn't know where to find them. Some can also use pin 34 to indicate RDY, ie that the drive is up to speed etc. The MON can also be ignored by some drives which use the select lines to activate the motor as well. This information is in no way guaranteed to be correct. Linus Torvalds torvalds@cc.helsinki.fi
feg@moss.ATT.COM (Forrest Gehrke,2C-119,7239,ATTBL) (02/19/91)
In article <1991Feb17.152818.4901@cc.helsinki.fi> torvalds@cc.helsinki.fi writes: >> In article <1991Feb12.215709.17456@coplex.uucp>, dannie@coplex.uucp (Dannie Gregoire) writes: >>> I have been trying to find some information on the hardware differences >>> between 720K and 1.44M floppies. Specifically, what are the differences >>> in the pin outs (and signals sent to the PC) between the drive's connectors. >>> >>> What signal (if any) is sent to the PC when the drive detects that a high >>> densisty has been inserted. > >Right, this info is straight from the EPSON SMD-340 3.5" floppy drive >manual (not guaranteed, but should of course work for others as well :-) > >Pin Name what? > >2 HDI High density in (low in 2MB mode (2MB unformatted=1.44MB)) >4 NC >6 DS3 Drive select 3 (low -> selected) >8 IDX* Index >10 DS0 Drive select 0 >12 DS1 Drive select 1 >14 DS2 Drive select 2 >16 MON Motor on (low - on) >18 DRTN Direction (low - step inwards) >20 STP step (transition low->high steps motor, usuallu 3 ms) >22 WTD Write data >24 WTG Write gate (active low) >26 TK00* Track 0 (low means we are on track 0) >28 WPT* Write protect (low means write protected) >30 RDD* Read data >32 SSL Side select (note low means side 1, high means side 0) >34 DCH* Disk change > >pins 1,3,5 not connected, others grounded. >* means signal from disk drive, otherwise to drive unit. > >NOTE! The HDI is not from drive to computer but the other way around. >This can force the drive to use 2MB mode (1.44MB). This is in fact not >used on most drives to my knowledge, as the drive senses the density >from the disk covering. This can be enabled by a jumper on my drives. > >There are drives available that use pin 2 as HDO (High density out) to >let the computer sense the density used, but I wouldn't know where to >find them. Some can also use pin 34 to indicate RDY, ie that the drive >is up to speed etc. The MON can also be ignored by some drives which use >the select lines to activate the motor as well. > >This information is in no way guaranteed to be correct. > > Linus Torvalds torvalds@cc.helsinki.fi To add to the above, as concerns Epson drives (I don't know about others): Just behind the 34 pin edge connector there are two rows of 8 pins each which are jumpered in various ways as follows (counting pins with least significant from left when looking at rear of drive): 9 x x x x x x x x 16 1 x x x x x x x x 8 14 to 15 Drive select 0 15 to 16 Drive select 1 (std. setting) 6 to 7 Drive select 2 7 to 8 Drive select 3 4 to 5 Mode switched to internal sensor (std. setting) 5 to 13 Mode switched by HDI input 1 to 2 2M mode set by HDI "high" 2 to 3 2M mode set by HDI "low" (std. setting) 9 Grounding 10 & 11 Test terminals 12 Test terminal As shipped 2 to 3 and 4 to 5 are jumpered. This results in the internal sensor turned on and formatting capacity determined by whether the floppy has one or two holes. Changing this to jumpers across 5 & 13 and 1 & 2 will result in the internal sensor being turned off. If a format is requested without command line sensors the floppy will be formatted to 1.44 MB regardless of whether the floppy has one or two holes. Formatting to 720 KB has to be requested with parameters, henceforth. Reading will be determined by whatever the diskette has been formatted, again, regardless of number of holes. I have formatted single sided double density diskettes I purchased in 1985 to 1.44MB without any difficulty. I don't think there is any difference in the media, at least among the various diskette manufacturers I have tried. This gets rid of the business of chopping holes in one hole diskettes. Forrest Gehrke feg@dodger.att.com