1 files changed, 67 insertions, 0 deletions

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