ewen@actrix.gen.nz (Ewen McNeill) (05/23/91)
A great big thank you to all the people who replied to my request for help with the Osborne 1 that I have been given. The verdict is that an IBM drive can be put into the machine, if one tries hard enough. One has to handle the power supply connections, which are a separate connector on the IBM drives, but on the underside of the Osborne drives. The IBM drives have an earth on the underside of the connector. Do *NOT* try connecting it up just to find out if it would work. Something will melt down. The verdict on the serial port and modem port appear to be that they are the same control lines inside the machine. The RS232 port apparently is only TTL levels, so some line driver/receivr chips would be needed. Speed choices are 300 and 1200, although there is apparently a link inside which can make this 600 or 2400 (from IMP overlay). The good news about my Osborne is that the B drive appears to be sort of working. It works once I have formatted a disk in it. I think the main reason that this works is that it causes the drive to step, and thus realign onto the disk. The BIOS in my Amstrad does this automatically when it has problems (steps out a track, and back, and also seeks to first/last track and back -- solves some problems). This semi-strongly suggests an alignment problem to me, so I might have a look around and see what I can fiddle with... :-) Anyway, thank you very much to everyone who offered help. -- Ewen McNeill, ewen@actrix.gen.nz
pa1@tdatirv.UUCP (Pat Alvarado) (05/28/91)
In article <1991May23.042256.12302@actrix.gen.nz> ewen@actrix.gen.nz (Ewen McNeill) writes: >The verdict on the serial port and modem port appear to be that they are >the same control lines inside the machine. The RS232 port apparently is >only TTL levels, so some line driver/receivr chips would be needed. >Speed choices are 300 and 1200, although there is apparently a link >inside which can make this 600 or 2400 (from IMP overlay). > The Osborne 1 uses the standard 1488 and 1489 chips to the external port of the RS232 interface, and uses +/- 12VDC to drive the signals. The speed of the RS232 port can be software selectable between two speeds. There is a way to strap the clock chip to allow up to 4800/9600 bps operation. This information is from my Osborne 1 Technical Reference Manual, which indicates on the schematic how to strap the clock chip. -- ||| Pat Alvarado | v Teradata Corporation | tdat!pa1@suntzu.sun.com /\ /\ 100 N. Sepulveda Blvd. | uunet!edsews!hacgate!tdat!pa1 /// \\\ El Segundo, Calif. 90245 | pa1@tdat.teradata.com
ewen@actrix.gen.nz (Ewen McNeill) (05/30/91)
In article <7@tdatirv.UUCP> pa1@tdatirv.UUCP (Pat Alvarado) writes: > In article <1991May23.042256.12302@actrix.gen.nz> ewen@actrix.gen.nz (Ewen McNeill) writes: > >The RS232 port apparently is > >only TTL levels, so some line driver/receivr chips would be needed. > > The Osborne 1 uses the standard 1488 and 1489 chips to the external port > of the RS232 interface, and uses +/- 12VDC to drive the signals. > Sorry, folks. I mis-read the data I was sent. TX, and RX are held at normal levels. Some of the information I was sent, however, noted that some control lines were held at +5V. This confused me, when I quickly put together a summary. > ||| Pat Alvarado | > v Teradata Corporation | tdat!pa1@suntzu.sun.com > /\ /\ 100 N. Sepulveda Blvd. | uunet!edsews!hacgate!tdat!pa1 > /// \\\ El Segundo, Calif. 90245 | pa1@tdat.teradata.com -- Ewen McNeill, ewen@actrix.gen.nz