From c5fd554a45ea98664677dc76939561a3f67e843d Mon Sep 17 00:00:00 2001 From: Jeff Parsons Date: Fri, 21 Oct 2016 23:58:27 -0700 Subject: [PATCH] New blog post --- _posts/2016-10-21-booting-pdp-11-basic.md | 34 +++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 _posts/2016-10-21-booting-pdp-11-basic.md diff --git a/_posts/2016-10-21-booting-pdp-11-basic.md b/_posts/2016-10-21-booting-pdp-11-basic.md new file mode 100644 index 000000000..bf8fb5e92 --- /dev/null +++ b/_posts/2016-10-21-booting-pdp-11-basic.md @@ -0,0 +1,34 @@ +--- +layout: post +title: Booting PDP-11 BASIC +date: 2016-10-21 23:00:00 +permalink: /blog/2016/10/21/ +machines: + - id: test1120 + type: pdp11 + debugger: true + autoMount: '' + config: /devices/pdp11/machine/1120/basic/debugger/machine.xml +--- + +[PDPjs](http://www.pcjs.org/devices/pdp11/machine/) can now simulate a PDP-11/20. It was one of the first PDP-11 +models, and since it had no MMU, it was limited to a maximum of 56Kb of RAM (or as DEC would say, 28K words), since +the top 8Kb (or 4K words) of its 16-bit address space was reserved for UNIBUS devices. + +The first PDPjs test of a PDP-11/20 configuration was attempting to run [PDP-11 BASIC](/apps/pdp11/tapes/basic/), by loading +it directly into memory from the original paper tape image. This required changes to the [RAM](/modules/pdp11/lib/ram.js) +component, including a new *loadImage()* interface that understands DEC's paper tape format. + +To provide a more "authentic" experience, there is also a new [PC11 Paper Tape](/modules/pdp11/lib/pc11.js) component, +and machines can now be configured to include a virtual paper tape reader, with an [assortment of paper tapes](/devices/pdp11/pc11/) +ready to be attached. + +In the real world, before you could load *any* paper tape, you had to first enter a +[Bootstrap Loader](/apps/pdp11/boot/bootstrap/). PDPjs has simplified that process by including the Bootstrap Loader as +just another paper tape image that you can "Load" directly into memory. Once that has been loaded, you can then read any +other paper tape image, once you "Attach" it to the paper tape reader. + +{% include machine.html id="test1120" %} + +*[@jeffpar](http://twitter.com/jeffpar)* +*Oct 21, 2016*