diff --git a/Makefile b/Makefile
index 19ec8fe2..a9091499 100644
--- a/Makefile
+++ b/Makefile
@@ -39,7 +39,7 @@ DOC = info _info_ sysdoc sysnet syshst kshack _teco_ emacs emacs1 c kcc \
       digest prs decus
 BIN = sys sys1 sys2 emacs _teco_ lisp liblsp alan inquir sail comlap \
       c decsys graphs draw datdrw fonts fonts1 fonts2 games macsym \
-      maint imlac _www_ gt40 llogo bawden sysbin -pics- lmman r shrdlu \
+      maint _www_ gt40 llogo bawden sysbin -pics- lmman r shrdlu \
       pdp10
 MINSRC = midas system $(DDT) $(SALV) $(KSFEDR) $(DUMP)
 
diff --git a/bin/imlac/imlac.blkldr b/bin/imlac/imlac.blkldr
deleted file mode 100644
index 364d9c6b..00000000
--- a/bin/imlac/imlac.blkldr
+++ /dev/null
@@ -1,6 +0,0 @@
-!blk ldr!
-@BAJH@@IBGOLBGOMCONGCONGH@@FBGONCOMOGOOHAGLL@@@@BGOOCOMOJGO
-OCOMHCGOOCGONAGLMCOMOGGOLHD@AAGL@@@@@@@@@H@@HFOOL@D@DH@@DBGO
-LIGMH@@@@H@@IBGOMCONGCONGCONGCONGIGMO@@@@@DB@AGNHH@@I@BAKBG
-KODOOIGOOJAGNHFGKODOOKBOOM@F@C@F@AEGOMBGOMIGNGOOOO@@G@@@D@@
-@@O@@@@OOOOOO@A@OJJOOL@
diff --git a/build/misc.tcl b/build/misc.tcl
index 9b9a88de..6856e94d 100644
--- a/build/misc.tcl
+++ b/build/misc.tcl
@@ -1360,6 +1360,31 @@ expect ":KILL"
 respond "*" ":midas sys2; ts tvedit_sysen2; tvedit\r"
 expect ":KILL"
 
+# BLKLDR, Imlac secondary block loader.
+respond "*" ":midas sysbin;_imsrc; blkldr\r"
+expect ":KILL"
+# IMTRAN will put the file IMLAC; IMLAC BLKLDR first in its output.
+# The BLKLDR file should say !blk ldr! on the first line.
+respond "*" ":create imlac; imlac blkldr\r"
+respond "help." "!blk ldr!\r\003"
+respond "*" "imtran\033\013"
+# The IMTRAN output is in block loader format, but the block loader
+# itself is in the special TTY bootstrap format.  Patch IMTRAN to not
+# write flat data without blocks.
+respond "@" "\032"
+type "smalup+5/"
+respond "EMIT2" "jfcl\r"
+type "smalup+11/"
+respond "EMIT4" "jfcl\r"
+type "datlup+4/"
+respond "EMIT4" "jfcl\r"
+type "prgend/"
+type "jrst prgen1+4\r"
+type "\033p"
+type "imlac; imlac blkldr_sysbin; blkldr bin\r"
+respond "@" "\021"
+expect ":KILL"
+
 # SSV 22, Imlac scroll saver
 respond "*" ":midas;324 sysbin;_imsrc; ssv22\r"
 expect ":KILL"
diff --git a/doc/programs.md b/doc/programs.md
index 9823aa83..2e194960 100644
--- a/doc/programs.md
+++ b/doc/programs.md
@@ -39,6 +39,7 @@
 - BINPRT, display information about a binary executable file.
 - BITPRT, print JCL as bits.
 - BKG, a Backgammon game.
+- BLKLDR, Imlac secondary block loader.
 - BOLIO, typesetting.
 - BOOTVT, GT40 boot ROM.
 - BYE, say goodbye to user. Used in LOGOUT scripts.
diff --git a/src/imsrc/blkldr.1 b/src/imsrc/blkldr.1
new file mode 100644
index 00000000..03d0b5d5
--- /dev/null
+++ b/src/imsrc/blkldr.1
@@ -0,0 +1,86 @@
+TITLE BLKLDR 1 (PDL) 12/7/73
+
+.INSRT IMDEFS >
+LDADR=37700
+	LOC LDADR
+			; ADDR	CHAR	OCTAL
+
+START:	RCF		; 00:	@BAJ	001032
+	CAL		; 	H@@I	100011
+	DAC CHKSUM	; 	BGOL	023774
+	DAC WRD		; 	BGOM	023775
+	JMS GET4	; 	CONG	037747
+	JMS GET4	; 	CONG	037747
+	CIA		; 	H@@F	100006
+	DAC COUNT	;	BGON	023776
+	JMS GET16	; 10:	COMO	037737
+	SAM MINUS1	;	GOOH	077770
+	JMP .+2		;	AGLL	013714
+	HLT		;	@@@@	000000	; DONE. THIS LOC GETS GLOBBERED FOR AUTOSTART.
+	DAC ADDRES	;	BGOO	023777
+BLKLUP:	JMS GET16	;	COMO	037737
+	DAC @ADDRES	;	JGOO	123777
+	JMS CKS		;	COMH	037730
+	ISZ ADDRES	; 20:	CGOO	033777
+	ISZ COUNT	;	CGON	033776
+	JMP BLKLUP	;	AGLM	013715
+	JMS GET16	;	COMO	037737
+	SUB CHKSUM	;	GGOL	073774
+	ASN		;	HD@A	102001
+	JMP START	;	AGL@	013700
+	HLT		;	@@@@	000000	; CHECKSUM FAILED (SHOULD BE FIXED!).
+
+; update checksum
+CKS:	0		; 30:	@@@@	000000
+	CLL		;	H@@H	100010
+	ADD CHKSUM	;	FOOL	067774
+	LSZ		;	@D@D	002004
+	IAC		;	H@@D	100004
+	DAC CHKSUM	;	BGOL	023774
+	JMP @CKS	;	IGMH	113730
+
+; get word
+GET16:	0		;	@@@@	000000
+	CAL		; 40:	H@@I	100011
+	DAC WRD		;	BGOM	023775
+	JMS GET4	;	CONG	037747
+	JMS GET4	;	CONG	037747
+	JMS GET4	;	CONG	037747
+	JMS GET4	;	CONG	037747
+	JMP @GET16	;	IGMO	113737
+
+; get good character
+GET4:	0		;	@@@@	000000
+GETCHR:	RSF		; 50:	@DB@	002040
+	JMP .-1		;	AGNH	013750
+	CAL		; 	H@@I	100011
+	RRC		;	@BAK	001033
+	DAC START-1	;	BGKO	023677
+	AND M160	;	DOOI	047771
+	SAM M100	;	GOOJ	077772
+	JMP GETCHR	;	AGNH	013750
+	LAC START-1	; 60:	FGKO	063677
+	AND M17		;	DOOK	047773
+	XAM WRD		;	BOOM	027775
+	RAL 3		;	@F@C	003003
+	RAL 1		;	@F@A	003001
+	IOR WRD		;	EGOM	053775
+	DAC WRD		;	BGOM	023775
+	JMP @GET4	;	IGNG	113747
+
+; constant area
+MINUS1:	-1		; 70:	OOOO	177777
+M160:	160		;	@@G@	000160
+M100:	100		;	@@D@	000100
+M17:	17		;	@@@O	000017
+
+; variable area
+CHKSUM:	0		;	@@@@	000000
+WRD:	0		;	@@@@	000000
+COUNT:	0		;	@@@@	000000
+ADDRES:	0		;	@@@@	000000
+
+GOADDR:	LDADR		; 0:	COL@ 37700
+
+	END
+
\ No newline at end of file