Subject: Re: Osborne I and disk drives Date: 28 Jan 2000 01:20:50 GMT From: Don Maslin Organization: CTS Network Services Newsgroups: comp.os.cpm References: <86om0r$m9v$1@haavi.uwasa.fi> <3890E393.BF1BD86E@neo.rr.com> Barry Watzman wrote: : Sure; the interface is identical, just do it. Should not take any : changes. However, you won't be using any of the added capacity (80 : tracks vs. 40, or higher density) unless you make software changes that : are probably out of the question unless you have source code. : Barry Watzman I don't think so, Barry. Remember, the Osborne carries drive power in the ribbon cable also. The following is from a 1997 posting in this newsgroup: -------------- From the Osborne 1 Technical Manual, Part No. 2F00153-01 [1982] Chapter 7, Disk Drives -- Page 37 " 7.3 DISK CONTROLLER AND PINOUTS The disk controller chip used on the main logic board is the Fujitsu 8877, equivalent to the Western Digital 1793. The following pinouts apply to the disk cable connector on the main logic board. pin 1 GND 2 GND 3 GND 4 GND 5 GND 6 GND 7 GND 8 INDEX 9 GND 10 DRIVE SELECT 1 11 +12 volts 12 DRIVE SELECT 2 13 +12 volts 14 NC 15 +12 volts 16 4mhz clock 17 +12 volts 18 DIR 19 GND 20 STEP 21 +5 volts 22 WRITE DATA 23 +5 volts 24 WRITE GATE 25 +5 volts 26 TRACK 00 27 GND 28 WRITE PROTECT 29 GND 30 READ DATA 31 GND 32 SIDE SELECT 33 GND 34 LATE Figure 7.3 Main Board Disk Cable Connector Pinouts So the answer seems to be, yes, it is possible, but not exactly simple. - don : Jukka Aho wrote: :> Is there any simple way to interface a standard 3.5" disk drive :> to Osborne I (electrically replacing one of the internal drives, :> so that the Osborne thinks it is controlling a 5.25" drive while :> it really isn't)? Or swapping in another 5.25" floppy drive :> mechanism? :> :> -- znark