Initial commit (a clone of the jsmachines project as of v1.15.3)

blog/2014/08/01/README.md

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+PC Tech Journal, 1987
+---
+As part of an ongoing effort to make classic PC technical literature more accessible, I just finished
+scanning and posting the 12 issues of [PC Tech Journal](/pubs/pc/magazines/pctj/) from 1987.
+
+![PC Tech Journal, Jan 1987](http://static.pcjs.org/pubs/pc/magazines/pctj/PCTJ-1987-01/thumbs/PCTJ-1987-01 1.jpeg "link:/pubs/pc/magazines/pctj/PCTJ-1987-01/:200:260")
+
+Future PC Tech Journal postings will include:
+
+- Vol. 1, No. 1, July-August 1983
+- Vol. 3, No. 12, December 1985
+- Vol. 4, Nos. 1-12, 1986
+- Vol. 6, Nos. 1-12, 1988
+
+I'm missing the rest of 1983, all of 1984, most of 1985, and all of 1989 (well, through April 1989, which was
+apparently the last issue).
+  
+For a nice overview and brief history of PC Tech Journal, check out the [OS/2 Museum](http://www.os2museum.com/wp/?p=2478). 
+
+In the meantime, if you have old PC Tech Journal issues that would fill any of the above holes, let me know.
+I'd be happy to buy them, scan them, and recycle them.
+
+Thanks.
+
+*[@jeffpar](http://twitter.com/jeffpar)*  
+*August 1, 2014*

blog/2014/08/28/README.md

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+Supporting the 80286
+---
+The next milestone for PCjs is complete 80286 emulation.  My hope is to have it working by the end of the year.
+
+PCjs version 1.15.0 is the first step on the path to full 80286 support.  It includes changes to the physical
+memory manager and separate real-mode and protected-mode address evaluators.  The Debugger supports physical
+addresses (eg, %FE05B is the same as F000:E05B, assuming real-mode operation), along with breakpoint commands that
+stop execution on port input/output operations.  And the ChipSet component now contains "infrastructure" (a
+fancy way of saying "partial support") for multiple PICs, DMA controllers, the 8042 keyboard controller (including
+A20 support), and a bit more -- but not much.
+
+One of the challenges is creating a single "universal" version of PCjs that can adapt itself to different machine
+types without impacting performance.  There will not be a **pc8088.js** or a **pc80286.js** or whatever.  There will
+only be **pc.js**.
+
+Up until now, all PCjs machine XML files assumed an 8088 CPU with a 20-bit bus and a model 5150 or 5160 motherboard.
+But now, a machine XML file can specify:
+
+	<computer name="IBM PC AT" buswidth="24"/>
+    <cpu model="80286"/>
+    <chipset model="5170"/>
+	...
+	
+Conventional emulators are usually NOT able to run original BIOS images, or simulate original PC hardware,
+or even run at the same speed as the original PC, making some software difficult or impossible to use.  PCjs takes a
+different approach, by attempting to simulate an entire PC as it originally existed.  Which is why a PCjs simulation
+of an IBM PC does NOT run at whatever speed your modern PC happens to run in V86-mode or whatever speed your
+browser's JavaScript engine tops out at.
+
+No, a PCjs simulation of a 4.77Mhz IBM PC runs at 4.77Mhz.  And a PCjs simulation of a 6Mhz IBM PC AT will run at
+6Mhz.  If you want to run the simulation faster, you have that option, but that's not the default.  And I'm not saying
+that PCjs is *exact* -- exactness is an exercise I'm leaving for another day and/or to other developers who are even
+more obsessive than I am.  I'm just saying that original PCs represent the targets that PCjs is shooting for.
+
+PCjs 1.15.0 can now load and run the IBM 5170 ROM BIOS up to the first 80286-specific opcode, so it's off and running.
+Although "running" isn't quite the right metaphor, because the process of bringing a new machine simulation to
+completion is a *very* long series of baby steps.
+
+Also, in preparation for this new phase, I recently dug up a variety of old [80286 CPU Documentation](/pubs/pc/reference/intel/80286/)
+and posted excerpts.  I'm sure none of this information is "new" at this point, but it might have some historical interest.
+
+Enjoy.
+ 
+*[@jeffpar](http://twitter.com/jeffpar)*  
+*August 28, 2014*