wjc@llex.ll.mit.edu ( Bill Chiarchiaro) (06/06/91)
About two weeks ago, I posted a problem I had getting my HP48SX (rev. E) to talk with my old Leading Edge PC. The PC could get characters to the 48, but wouldn't hear any coming from the 48. I thought I had a BIOS bug, but have since shot down that theory. I currently believe that it is a hardware interrupt problem. In any event, I have found a version of kermit which has aided my diagnosis of this problem and has also allowed a work-around. Version 3.10 of mskermit (available from watsun.cc.columbia.edu) features great versatility in its IO. It will check whether your PC has 8250 async chips. If so, it will talk to them directly (bypassing the BIOS) and use hardware interrupts for receiving characters. If you don't have 8250s, it will automatically fall back to using BIOS calls. Furthermore, you can force it to use BIOS calls even if you have 8250s by giving a "SET PORT BIOSn" command where "n" is the port number. I have used this kermit in BIOS mode to transfer data with my 48. In order to get reliable service, I had to run the connection at 1200 bps. Actually, this results in only a factor of 4 reduction in throughput as compared to running at 9600 bps with the PC in my office. I suspect the 48 can't keep the communication path full at 9600. If other people are still interested in this problem, feel free to get in touch with me. Bill Chiarchiaro wjc@ll.mit.edu
rrd@hpfcso.FC.HP.COM (Ray Depew) (06/07/91)
Re: HP48 kermit problems Are you using the "official HP" cable, or a homebrew? If homebrew, is your shield grounded? Just a thought (or two)... Regards Ray Depew HP ICBD -- IC's by dictatorship rrd@hpfitst1.hp.com