pepers@enme1.ucalgary.ca (Brad Pepers) (02/18/91)
I recently bought an Osborne 1 computer. My hobby is buying old computers so don't think I bought it thinking I could use it for much. But I would like to try and find some software for it. Any FTP sites? Anyone have some old Osborne software they want to sell? It has 2 5 1/4 drive, a 300 baud modem, 64k, CP/M 2.2, and a 5 inch monitor! Thanks! Brad Pepers (pepers@enme.ucalgary.ca or pepers@cpsc.ucalgary.ca)
Charles.Cotham@farwest.FidoNet.Org (Charles Cotham) (05/23/91)
Ewen,
I am talking off the top of my head right now, my tech manual are at
the house, but I believe that the Osb-1 serial port has normal RS-232
levels. The modem port is the port with the TTL levels, I have a
schematic at the house to build an adapter to change the modem port to
regular 232 levels using , 1488 and 1489 driver chips as I remember. It
also has the resistances to insert in the other lines on the Modem Port.
To use the Serial port with a Hayes type modem you have to use pins 2 &
3 reversed to the modem and pin 7 to pin 7 on the modem. Imp 244 works
real well on mine and ZMP 15 with zmodem protocal is also nice. I have a
couple of articles on drive alignment and a mod to increase the
readability of Osborne drive span with a capacitor change. Leave me a
note or my address is below if you would like some of the info I have. I
would be glad to send it to you. See you later. Love my OZZIE.
Charles Cotham
2205 Lilac Street
Nederland, Tx 77627
PS: Heck I love all 8 of my Ozzies
* Origin: Two Wheelers - The Bicylists' Communications Link (1:106/88)cummings@PRIMERD.PRIME.COM (Kevin J. Cummings) (05/28/91)
I tried conmecting an Osborne 1 to my S100 machine via its SSM IO/4 card. The SSM card would drive RS-232 via a 1488 chip @ +/- 12V, but would receive RS-232 via a couple of transistors (had to do with the board's capability of running current loops instead of EIA, if you strapped it right). The transistor bridge was little more than a voltage divider (it divided the incoming voltage by 3 if I remember right). RS-232 signals which were driven at +/- 12V would be converted to +/-4 Volts, which seems to work OK with the on board TTL circuts. HOWEVER, when I connected this to the Osborne-1 serial port, I was only getting 1-way communication. From the SSM to the osborne worked OK. It was the Osborne to SSM line which didn't work (at all). This turned out to be that the Osborne used a -9V (which while being within the EIA specifications for RS-232C voltages) which is not common. It did however use +12V for the other voltage level. The result was that the SSM receiver would divide the -9 down to -3V which is never-never land for TTL levels, and the SSM board woould fail. (Now before I get flamed, I know that TTL uses 0V (gnd) for 0, and 3.5V or so to about 9V for 1, so I must not be remembering the entire receive circut on the SSM board from memory, and my schematic for it is at home right now. Somewhere the circut converted the +/- signals into +/0V.) While +12/-9 is within the EIA spec, the Osborne is the ONLY peice of RS-232 compliant equipment I have used with my SSM that didn't work (without a -12V pull down being added to the input circut). I therefore have trouble believing that the Osborne uses "normal RS-232 levels". I do however believe that if the SSM board had used a 1489 for its receiver, that it would have "done the right thing" with the signals received from the Osborne. Caveat Empteur.