Loading BASIC from Papertape
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by Bill Degnan - 07/27/2013 23:35 |
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Video of BASIC running
http://youtu.be/ymkHxZo-WIQ Recap Since June of 2009 I have been working on this system. It's been a challenge putting all of the pieces together to implement a working "stock" PDP 11/05 with one 8K core memory (037744) and an unmodified teletype for I/O. I decided that I'd attempt to load BASIC despite the lack of a 4915 Reader Run card. I was told it might not be necessary and I decided I had nothing to lose. Steps I took to Load BASIC without a Reader Run card: 1. Toggle in the bootstrap loader (listed above) for 8K low-speed reader. 2. I found a papertape with "Absolute Bootstrap V6" written on on it. I did not know if it was right or not but I'd give it a try. I put the absolute loader tape on the teletype reader. 3. Next I set the front panel to bootstrap loader address and pressed START. I then switched the Teletype's reader START lever up. The tape began to read into the PDP 11 and I watched the lights on the front panel as it progressed. It appeared as if the bootstrap loader ran properly and in doing so caused the absolute loader program to load into memory successfully. The tape ended and simultaneously the RUN light went out. 4. I stopped the system and loaded the BASIC tape. I set the appropriate loader values on the front panel and then set the absolute loader address for BASIC. I pressed START on the PDP 11 and then I engaged the teletype reader start switch (press up). The teletype read the BASIC tape into the PDP 11. 5. It took about 20-30 minutes for the BASIC tape to read. During this time the system lights blinked at a high rate and the RUN light stayed on. This was a good sign. 6. As described in the DEC Papertape BASIC manual, the tape finished and the system initiated the BASIC program automatically. I was quite amazed that it worked! 7. After running a few tests I got out my video camera to record the initial testing. NEXT - Can you save and load BASIC programs on papertape without the reader run card? Reply |
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