From 9f4aa97822adc791f700670ef0fc7636849563b7 Mon Sep 17 00:00:00 2001
From: Julian Blake Kongslie
Date: Sat, 29 Oct 2022 18:18:26 -0700
Subject: Understanding interrupt handling within SIMH (see echo_int.pal)

Add list of Bugs

Add event log file parser

More changes associated with widening the ctlregs (FIXME add a typedef)

Add some keyboard instructions
---
 programs/echo_optimal.pal | 67 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 programs/echo_optimal.pal

(limited to 'programs/echo_optimal.pal')

diff --git a/programs/echo_optimal.pal b/programs/echo_optimal.pal
new file mode 100644
index 0000000..1281309
--- /dev/null
+++ b/programs/echo_optimal.pal
@@ -0,0 +1,67 @@
+/ vim: set sw=8 noexpandtab :
+
+*000
+
+INTRET,	0
+	JMP GOTINT
+
+*010
+
+HEAD,	7777		/ because preincrement
+TAIL,	7777
+
+*100
+
+TTBUSY,	0		/ FIXME: sometimes we get wedged with TTBUSY=1, but TT flag is clear (no TT interrupt occurs)
+
+*200
+
+	CLA IAC
+	KIE
+	ION
+	CLA
+LOOP,	TAD TTBUSY
+	SZA
+	JMP LOOP
+	TAD TAIL
+	CMA IAC
+	TAD HEAD
+	SNA
+	JMP LOOP
+	CLA
+	CDF 0010
+	TAD I TAIL
+	CDF 0000
+	IOF		/ critical section
+	TPC
+	CLA IAC
+	ION
+	DCA TTBUSY	/ end critical section
+	JMP LOOP
+
+*400
+
+SAVEA,	0
+SAVEF,	0
+
+GOTINT,	DCA SAVEA
+	GTF
+	AND (7577)
+	DCA SAVEF
+	TSF
+	JMP KBIN
+	DCA TTBUSY
+	TCF
+KBIN,	KSF
+	JMP RETINT
+	KRB
+	CDF 0010
+	DCA I HEAD
+	CDF 0000
+RETINT,	CLA
+	TAD SAVEF
+	RTF
+	CLA
+	TAD SAVEA
+	ION
+	JMP I INTRET
-- 
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