Information on LDDT:
	LDDT is a package of functions for manipulating inferior jobs using
the HUMBLE package (NEWIO) or JOBLAP (OLDIO).  The source is MC:JLK;LDDT >
Many of the functions are used in a fashion similar to DDT commands of the
same name, e.g. (g 69) in LDDT is like 69G in DDT.

Special variables in LDDT:

NULL	- Has a value of (ASCII 0) for surreptitious returns.

*BREAK16-FUNCTION - Its value is an atom which is applied to the
	effective address of .BREAK 16, requests from the inferior.
	This is the primary communication mechanism from the inferior
	job to LISP routines in the superior LISP.

*VALUE	- Its value is an atom whose function property is a handler for
	.VALUE returns from an inferior.

*BREAK	- Its value is an atom whose function property handles .BREAK's
	  (calls .BREAK 16, handler, .BREAK 12, handler, etc.)

CURRENT-JOB	- A pointer to the current JOB's JOB-array

DDT-READTABLE	- A readtable for reading commands in DDT syntax.
		  (not developed very far yet).

JOB-STACK	- A list used as a stack for pushing the current job while
		  handling job interrupts.

LISP-CURSORPOS	- Saved cursorposition when TTY is passed to TECO.

RETURNED-MSG	- Message printed on the bottom line of the screen when
		  the inferior returns with ^Z.

OUTCRCT		- Output character count (FILEPOS doesn't work on output files)

J*STADR		- 23 - The element of job-arrays containing the start-address.

J*CRUFT		- 3 - The job-array slot containing the job's PLIST

JOB-INTERRUPT-LIST - A list of atoms representing, in numerical order, names
		of interrupts.  The values of these atoms are handlers for
		these particular interrupts.
JOB-RING	  - The ring of current jobs.

JOB-INFORM	 - A file-array to the tty for informing the user of job
	behavior (.values, .ilopr's, etc not otherwise handled).

CRLF		- CRLF.  For routines that want to return quietly.

JOB-INTERRUPT-LIST :
TYPEIN ^ZTYPED BADPI AROV 340DPY ILOPR SYSDED  *VALUE IOC ILUAD *BREAK
1PROC SLOWCLOCK  MPV MAR LTPEN PDLOV CLI RESTR SYSDBG  ARMTP1 ARMTP2
ARMTP3 SYSUUO PURINS  PURPG ARFOV PARERR PITTY PIATY PIDCL <4/.5>
<4/.6> RUNTIM REALTM

EXTERNAL FUNCTIONS (in HUMBLE or JOBLAP):

p	- Start and give the tty to the current job.

JOB-USET-WRITE	- Write a user variable for the current job.
		  (see also LIBLSP;LUSETS MACRO)

JOB-USET-READ	- Read a user variable for the current job.

EXAMINE-JOB	- read a location in the inferior job.

DEPOSIT-JOB	- Deposit a value into some location of the current inferior job.

KILL-JOB	- Expunge the current job.

VALUE-STRING	- Read a string of characters from the inferior's memory
		  terminated with ^@.

*ATTY		- Give the TTY to the current inferior job.

*DTTY		- Take the TTY back from the inferior that has it.

CREATE-JOB	- Create a job.

SELECT-JOB	- Select a job to be the current job.

Functions in LDDT:

 PRINJ		- Princ to the JOB-INFORM channel

 TERPRJ		- TERPRI on the JOB-INFORM channel

 JOB-INTERRUPT-HANDLER	- Handler for job interrupts

 ARBITRATE-INTERRUPTS	- Arbitrate interrupts (decide which order to handle
			  simultaneous interrupts.  Current just takes them
			  in numerical order).

 PIRQC-DECODE		- Decode PIRQC into interrupt "atoms" on the
			  JOB-INTERRUPTS-LIST

 RANDOM-CLASS1-INTERRUPT - Handler for all unhandled class 1 interrupts.

 ^Z-INTERRUPT		- Handler for ^Z typed in the inferior (flush type-ahead).

 DEFERRED-CALL		- Handle deferred-call (don't flush type-ahead).

 CALC-EFF-ADR		- calculates the effective address in a word.

 *VALUE-HANDLER		- Default handler for .VALUE's

 *VALUE0		- Handler for .VALUE 0

 *VALUE-STRING		- Get string specified by .VALUE

 PUT-JCL		- set the JCL for a job.

 DDT			- enter a DDT like command reader (doesn't work yet)

 DDT-ALTMODE-MACRO	- Read macro for DDT commands beginning with altmode

 DDT-COLON-MACRO	- Read macro for DDT colon commands

 :JCL			-Set the JCL for a job

 :PROCEED		- proceed a job, but keep the tty.

 ^P			- Alias for PROCEED.

 :CONTIN			- Continue an existing job, giving it the tty.

 P			- Alias for CONTIN.

 :GZP			- Start and PROCEED a job.

 :START			- Start a job.

 START-JOB		-Start job.  2 args: location and TTY flag
			 (NIL= don't giveup the tty, otherwise give inferior
			  the tty).
 CONTINUE-JOB		- Continue existing job, One arg - TTY flags as above.

 G			- Alias for START

 J			- Select next job in the job ring.

 J			- Rename the current job.

 *BREAK-HANDLER		- Default handler for .BREAK's

 *BREAK16-HANDLER	- Default Handler for .BREAK 16,

 *BREAK12-HANDLER	- Default Handler for .BREAK 12,

 JOB-RETURNED-TTY	- Inform the user that an inferior job has returned
			  the TTY.

 PUSH-SELECT-JOB	- Push the current job on the stack and select the
			 job specified as an argument.

 POP-SELECT-JOB		- Pop a job off the job-stack and select it as current.