| MP/M & CP/NET [message #9394] |
Sun, 21 November 2021 04:15  |
tapy
Messages: 17
Registered: June 2021
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Junior Member |
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Hi all,
I would like to present my challenge I set myself to celebrate the 40th anniversary of MP/M II and CP/NET release. To realize my idea I used popular RC2014 kits, as a CP/NET network server I used Z180 computer working under MP/M, while the client stations are typical Z80 kits. On the client side CP/NET was loaded from CP/M v2.2 and on diskless computers with CP/NOS. As a network controller I used COM20020 working in Arcnet standard, in the physical layer RS485 driver - SN75176. The use of this archaic standard was dictated by the desire to preserve the "spirit of the times" so as not to use contemporary solutions using microcontrollers superior in performance to the entire network to support the TCP/IP stack and Ethernet. At the moment the whole thing is up and running, but I still need to add code to support frames longer than 252 bytes. I'm not entirely satisfied with the results as I had to give up using interrupts for incoming packets as MP/M randomly crashed during heavy disk usage by requesters. It is possible that this is due to my misunderstanding of the operation of the rather peculiarly programmed Arcnet controller, or that MP/M quite often disables the interrupt system during its operation. I will continue to work on this problem, as using interrupts is more "elegant" than using polling for incoming packets. I think I'll get this project out to the community by this anniversary.
Tadeusz Pycio
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