From e936815bb67f94776eb74717f00eb008160a34f6 Mon Sep 17 00:00:00 2001
From: Jeff Parsons <Jeff@pcjs.org>
Date: Mon, 25 Apr 2016 18:43:31 -0700
Subject: [PATCH] README update

---
 devices/pc8080/machine/invaders/README.md | 122 +---------------------
 versions/pcjs/1.21.7/components.xsl       |  33 +++++-
 2 files changed, 35 insertions(+), 120 deletions(-)

diff --git a/devices/pc8080/machine/invaders/README.md b/devices/pc8080/machine/invaders/README.md
index 7983d7168..48495f194 100644
--- a/devices/pc8080/machine/invaders/README.md
+++ b/devices/pc8080/machine/invaders/README.md
@@ -23,7 +23,7 @@ The idea is to make [PC8080](/modules/pc8080/) sufficiently configurable so that
 terminal-based systems, like the CP/M-based systems of old.
 
 In fact, as soon as Space Invaders is working, my next adaptation will be a DEC VT100 terminal emulator (itself
-an 8080-based machine) which can then "wired up" to other PCjs machine simulations.  
+an 8080-based machine) which can then be "wired up" to other PCjs machine simulations.  
 
 Assorted [Space Invaders Hardware Notes](#space-invaders-hardware-notes) are collected below.
 
@@ -32,121 +32,5 @@ Assorted [Space Invaders Hardware Notes](#space-invaders-hardware-notes) are col
 Space Invaders Hardware Notes
 ---
 
-From [emutalk.net](http://www.emutalk.net/threads/38177-Space-Invaders):
-
-	Space Invaders, (C) Taito 1978, Midway 1979
-	
-	CPU: Intel 8080 @ 2MHz (CPU similar to the (newer) Zilog Z80)
-	
-	Interrupts: $cf (RST 8) at the start of vblank, $d7 (RST $10) at the end of vblank.
-	
-	Video: 256(x)*224(y) @ 60Hz, vertical monitor. Colours are simulated with a
-	plastic transparent overlay and a background picture.
-	Video hardware is very simple: 7168 bytes 1bpp bitmap (32 bytes per scanline).
-	
-	Sound: SN76477 and samples.
-	
-	Memory map:
-	        ROM
-	        $0000-$07ff:    invaders.h
-	        $0800-$0fff:    invaders.g
-	        $1000-$17ff:    invaders.f
-	        $1800-$1fff:    invaders.e
-	
-	        RAM
-	        $2000-$23ff:    work RAM
-	        $2400-$3fff:    video RAM
-	
-	        $4000-:         RAM mirror
-	
-	Ports:
-	        Read 1
-	        BIT     0       coin (0 when active)
-	                1       P2 start button
-	                2       P1 start button
-	                3       ?
-	                4       P1 shoot button
-	                5       P1 joystick left
-	                6       P1 joystick right
-	                7       ?
-	
-	        Read 2
-	        BIT     0,1     dipswitch number of lives (0:3,1:4,2:5,3:6)
-	                2       tilt 'button'
-	                3       dipswitch bonus life at 1:1000,0:1500
-	                4       P2 shoot button
-	                5       P2 joystick left
-	                6       P2 joystick right
-	                7       dipswitch coin info 1:off,0:on
-	
-	        Read 3          shift register result
-	
-	        Write 2         shift register result offset (bits 0,1,2)
-	        Write 3         sound related
-	        Write 4         fill shift register
-	        Write 5         sound related
-	        Write 6         strange 'debug' port? eg. it writes to this port when
-	                        it writes text to the screen (0=a,1=b,2=c, etc)
-	
-	        (write ports 3,5,6 can be left unemulated, read port 1=$01 and 2=$00
-	        will make the game run, but but only in attract mode)
-	
-	I haven't looked into sound details.
-	
-	16 bit shift register:
-	        f              0        bit
-	        xxxxxxxxyyyyyyyy
-	
-	        Writing to port 4 shifts x into y, and the new value into x, eg.
-	        $0000,
-	        write $aa -> $aa00,
-	        write $ff -> $ffaa,
-	        write $12 -> $12ff, ..
-	
-	        Writing to port 2 (bits 0,1,2) sets the offset for the 8 bit result, eg.
-	        offset 0:
-	        rrrrrrrr                result=xxxxxxxx
-	        xxxxxxxxyyyyyyyy
-	
-	        offset 2:
-	          rrrrrrrr      result=xxxxxxyy
-	        xxxxxxxxyyyyyyyy
-	
-	        offset 7:
-	               rrrrrrrr result=xyyyyyyy
-	        xxxxxxxxyyyyyyyy
-	
-	        Reading from port 3 returns said result.
-	
-	Overlay dimensions (screen rotated 90 degrees anti-clockwise):
-	        ,_______________________________.
-	        |WHITE            ^             |
-	        |                32             |
-	        |                 v             |
-	        |-------------------------------|
-	        |RED              ^             |
-	        |                32             |
-	        |                 v             |
-	        |-------------------------------|
-	        |WHITE                          |
-	        |         < 224 >               |
-	        |                               |
-	        |                 ^             |
-	        |                120            |
-	        |                 v             |
-	        |                               |
-	        |                               |
-	        |                               |
-	        |-------------------------------|
-	        |GREEN                          |
-	        | ^                  ^          |
-	        |56        ^        56          |
-	        | v       72         v          |
-	        |____      v      ______________|
-	        |  ^  |          | ^            |
-	        |<16> |  < 118 > |16   < 122 >  |
-	        |  v  |          | v            |
-	        |WHITE|          |         WHITE|
-	        `-------------------------------'
-	
-	        Way of out of proportion :P
+See [Computer Archeology](http://www.computerarcheology.com/Arcade/SpaceInvaders/) for an excellent collection
+of materials on the original Space Invaders, including commented ROM disassemblies. 
diff --git a/versions/pcjs/1.21.7/components.xsl b/versions/pcjs/1.21.7/components.xsl
index 48347394f..c8df6853b 100644
--- a/versions/pcjs/1.21.7/components.xsl
+++ b/versions/pcjs/1.21.7/components.xsl
@@ -1036,10 +1036,41 @@
 				<xsl:otherwise>false</xsl:otherwise>
 			</xsl:choose>
 		</xsl:variable>
+		<xsl:variable name="aspectRatio">
+			<xsl:choose>
+				<xsl:when test="@aspect"><xsl:value-of select="@aspect"/></xsl:when>
+				<xsl:when test="@aspectRatio"><xsl:value-of select="@aspectRatio"/></xsl:when>
+				<xsl:otherwise>0</xsl:otherwise>
+			</xsl:choose>
+		</xsl:variable>
+		<xsl:variable name="frameBuffer">
+			<xsl:choose>
+				<xsl:when test="@frameBuffer"><xsl:value-of select="@frameBuffer"/></xsl:when>
+				<xsl:otherwise>0</xsl:otherwise>
+			</xsl:choose>
+		</xsl:variable>
+		<xsl:variable name="interruptRate">
+			<xsl:choose>
+				<xsl:when test="@interruptRate"><xsl:value-of select="@interruptRate"/></xsl:when>
+				<xsl:otherwise>0</xsl:otherwise>
+			</xsl:choose>
+		</xsl:variable>
+		<xsl:variable name="refreshRate">
+			<xsl:choose>
+				<xsl:when test="@refreshRate"><xsl:value-of select="@refreshRate"/></xsl:when>
+				<xsl:otherwise>60</xsl:otherwise>
+			</xsl:choose>
+		</xsl:variable>
+		<xsl:variable name="rotation">
+			<xsl:choose>
+				<xsl:when test="@rotation"><xsl:value-of select="@rotation"/></xsl:when>
+				<xsl:otherwise>0</xsl:otherwise>
+			</xsl:choose>
+		</xsl:variable>
 		<xsl:call-template name="component">
 			<xsl:with-param name="machine" select="$machine"/>
 			<xsl:with-param name="class">video</xsl:with-param>
-			<xsl:with-param name="parms">,model:'<xsl:value-of select="$model"/>',mode:<xsl:value-of select="$mode"/>,screenWidth:<xsl:value-of select="$screenWidth"/>,screenHeight:<xsl:value-of select="$screenHeight"/>,memory:<xsl:value-of select="$memory"/>,switches:'<xsl:value-of select="$switches"/>',scale:<xsl:value-of select="$scale"/>,charCols:<xsl:value-of select="$charCols"/>,charRows:<xsl:value-of select="$charRows"/>,fontROM:'<xsl:value-of select="$fontROM"/>',screenColor:'<xsl:value-of select="$screenColor"/>',touchScreen:'<xsl:value-of select="$touchScreen"/>',autoLock:<xsl:value-of select="$autoLock"/></xsl:with-param>
+			<xsl:with-param name="parms">,model:'<xsl:value-of select="$model"/>',mode:<xsl:value-of select="$mode"/>,screenWidth:<xsl:value-of select="$screenWidth"/>,screenHeight:<xsl:value-of select="$screenHeight"/>,memory:<xsl:value-of select="$memory"/>,switches:'<xsl:value-of select="$switches"/>',scale:<xsl:value-of select="$scale"/>,charCols:<xsl:value-of select="$charCols"/>,charRows:<xsl:value-of select="$charRows"/>,fontROM:'<xsl:value-of select="$fontROM"/>',screenColor:'<xsl:value-of select="$screenColor"/>',touchScreen:'<xsl:value-of select="$touchScreen"/>',autoLock:<xsl:value-of select="$autoLock"/>,aspectRatio:<xsl:value-of select="$aspectRatio"/>,frameBuffer:<xsl:value-of select="$frameBuffer"/>,interruptRate:<xsl:value-of select="$interruptRate"/>,refreshRate:<xsl:value-of select="$refreshRate"/>,rotation:<xsl:value-of select="$rotation"/></xsl:with-param>
 		</xsl:call-template>
 	</xsl:template>