From bda85e8902d8b1627c7ec84900039c0ae9b69415 Mon Sep 17 00:00:00 2001
From: aap <aap@papnet.eu>
Date: Wed, 27 Apr 2016 19:14:06 +0200
Subject: [PATCH] final touches, added README

---
 Makefile  |  6 +-----
 README.md | 39 +++++++++++++++++++++++++++++++++++++++
 main.c    |  4 ++--
 3 files changed, 42 insertions(+), 7 deletions(-)
 create mode 100644 README.md

diff --git a/Makefile b/Makefile
index d62aa21..c36da57 100644
--- a/Makefile
+++ b/Makefile
@@ -2,14 +2,10 @@ SRC=main.c apr.c mem.c io.c
 # clang
 #CFLAGS= -Wno-shift-op-parentheses -Wno-logical-op-parentheses \
 #        -Wno-bitwise-op-parentheses
-CFLAGS=  -g -Os \
-	-fno-diagnostics-show-caret \
+CFLAGS=  -fno-diagnostics-show-caret \
         -L/usr/local/lib -I/usr/local/include -lSDL -lSDL_image -lpthread
 
 
 pdp6: $(SRC) pdp6.h
 	$(CC) $(CFLAGS) $(SRC) -o pdp6
 
-as: test.s
-	as10 <test.s
-	rim2mem <a.rim >mem
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..6e79c19
--- /dev/null
+++ b/README.md
@@ -0,0 +1,39 @@
+# PDP-6 Simulator
+
+This project is an attempt to simulate the PDP-6 computer
+with front panel and blinkenlights on the logic level.
+The maintenance manual has flow charts, schematics and explanations:
+[Volume1](http://bitsavers.trailing-edge.com/pdf/dec/pdp6/F-67_166instrManVol1_Sep65.pdf)
+[Volume2](http://bitsavers.trailing-edge.com/pdf/dec/pdp6/F-67_166instrManVol2_Sep65.pdf)
+
+## Code
+
+The code is more or less a transcription of the schematics into C.
+This means you will not understand it unless you're familiar with the maintenance manual.
+Pulses are represented as functions, when a pulse triggers another pulse
+it does so by the `nextpulse` function which adds a pulse to the list of next pulses.
+In the main cpu loop the list of current pulses is iterated and each pulse is called,
+then (after checking some external signals) the current and next pulse lists are swapped
+and the process begins anew.
+The timing was not accurately modeled and there is room for improvement.
+Due to the inexact timing the hardware connections (through the memory and IO bus)
+were not implemented too accurately. This may change in the future.
+
+## Building
+
+The supplied makefile assumes gcc (there are flags to silence some stupid warnings).
+Otherwise you need SDL and pthread.
+
+## Running
+
+Only the cpu is implemented. There are no external devices yet.
+The only things missing from the cpu are the clock to generate interrupts
+and the repeat key mechanism.
+The simulator reads `fmem` and `mem` to initialise the memory and fast memory.
+
+## To do
+
+- clock and repeat
+- test thoroughly!
+- devices
+- timing
diff --git a/main.c b/main.c
index 8577f27..ecef388 100644
--- a/main.c
+++ b/main.c
@@ -903,11 +903,11 @@ error:
 
 		ff_lght[32].state = apr.fdf1;
 		ff_lght[33].state = apr.fdf2;
-		ff_lght[34].state = 0;
+		ff_lght[34].state = apr.ir & H6 && apr.mq & F1 && !apr.nrf3;
 		ff_lght[35].state = apr.nrf1;
 		ff_lght[36].state = apr.nrf2;
 		ff_lght[37].state = apr.nrf3;
-		ff_lght[38].state = 0;
+		ff_lght[38].state = apr.fsf1;
 		ff_lght[39].state = apr.chf7;
 
 		ff_lght[40].state = apr.dsf1;