To:	Users
From:	Bob Supnik
Subj:	PDP-11 Simulator Usage
Date:	15-Jun-2004

			COPYRIGHT NOTICE

The following copyright notice applies to both the SIMH source and binary:

   Original code published in 1993-2004, written by Robert M Supnik
   Copyright (c) 1993-2004, Robert M Supnik

   Permission is hereby granted, free of charge, to any person obtaining a
   copy of this software and associated documentation files (the "Software"),
   to deal in the Software without restriction, including without limitation
   the rights to use, copy, modify, merge, publish, distribute, sublicense,
   and/or sell copies of the Software, and to permit persons to whom the
   Software is furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be included in
   all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   ROBERT M SUPNIK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
   IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

   Except as contained in this notice, the name of Robert M Supnik shall not
   be used in advertising or otherwise to promote the sale, use or other dealings
   in this Software without prior written authorization from Robert M Supnik.

This memorandum documents the PDP-11 simulator.


1. Simulator Files

To compile the PDP-11, you must define VM_PDP11 as part of the compilation
command line.  If you want expanded file support, you must also define USE_INT64
and USE_ADDR64 as part of the compilation command line.

sim/		scp.h
		sim_console.h
		sim_defs.h
		sim_ether.h
		sim_fio.h
		sim_rev.h
		sim_sock.h
		sim_tape.h
		sim_timer.h
		sim_tmxr.h
		scp.c
		sim_console.c
		sim_ether.c
		sim_fio.c
		sim_sock.c
		sim_tape.c
		sim_timer.c
		sim_tmxr.c

sim/pdp11/	pdp11_defs.h
		pdp11_mscp.h
		pdp11_uqssp.h
		pdp11_xq.h
		pdp11_xq_bootrom.h
		pdp11_cpu.c
		pdp11_dz.c
		pdp11_fp.c
		pdp11_hk.c
		pdp11_io.c
		pdp11_lp.c
		pdp11_pclk.c
		pdp11_pt.c
		pdp11_rk.c
		pdp11_rl.c
		pdp11_rp.c
		pdp11_rq.c
		pdp11_tq.c
		pdp11_rx.c
		pdp11_ry.c
		pdp11_stddev.c
		pdp11_sys.c
		pdp11_tc.c
		pdp11_tm.c
		pdp11_ts.c
		pdp11_vh.c
		pdp11_xq.c
		pdp11_xu.c

2. PDP-11 Features

The PDP-11 simulator is configured as follows:

device		simulates
name(s)

CPU		J-11 CPU with 256KB of memory
-		FP11 floating point unit (FPA)
-		CIS11 commercial instruction set (CIS, off by default)
PTR,PTP		PC11 paper tape reader/punch
TTI,TTO		DL11 console terminal
LPT		LP11 line printer
CLK		line frequency clock
PCLK		KW11P programmable clock
DZ		DZ11 8-line terminal multiplexor (up to 4)
VH		DHQ11 8-line terminal multiplexor (up to 4)
RK		RK11/RK05 cartridge disk controller with eight drives
HK		RK611/RK06(7) cartridge disk controller with eight drives
RL		RLV12/RL01(2) cartridge disk controller with four drives
RP		RM02/03/05/80, RP04/05/06/07 Massbus style controller
		with eight drives
RQ		RQDX3 MSCP controller with four drives
RQB		second RQDX3 MSCP controller with four drives
RQC		third RQDX3 MSCP controller with four drives
RQD		fourth RQDX3 MSCP controller with four drives
RX		RX11/RX01 floppy disk controller with two drives
RY		RX211/RX01 floppy disk controller with two drives
TC		TC11/TU56 DECtape controller with eight drives
TM		TM11/TU10 magnetic tape controller with eight drives
TS		TS11/TSV05 magnetic tape controller with one drive
TQ		TQK50 TMSCP magnetic tape controller with four drives
XQ		DELQA/DEQNA Qbus Ethernet controller
XQB		second DELQA/DEQNA Qbus Ethernet controller
XU		DEUNA/DELUA Unibus Ethernet controller

The DZ, RK, HK, RL, RP, RQ, RQB, RQC, RQD, RX, RY, TC, TM, TS, TQ, XQ, XQB,
and XU devices can be set DISABLED.  RQB, RQC, RQD, RY, TS, XQB, and XU are
disabled by default.

The PDP-11 simulator implements several unique stop conditions:

	- abort during exception vector fetch, and register STOP_VEC is set
	- abort during exception stack push, and register STOP_SPA is set
	- trap condition 'n' occurs, and register STOP_TRAP<n> is set
	- wait state entered, and no I/O operations outstanding
	  (ie, no interrupt can ever occur)
	- a simulated DECtape runs off the end of its reel

The PDP-11 loader supports standard binary format tapes.  The DUMP command
is not implemented.

2.1 CPU

The CPU options include CPU mapping configuration (18b Unibus, 22b Unibus
with RH70-style controllers, 22b Unibus with RH11 style controllers, and
22b Qbus), the CIS instruction set, and the size of main memory.

	SET CPU U18		Unibus, no I/O map, 18b addressing
	SET CPU URH11		Unibus, I/O map with 22b addressing,
				18b mapped RH11 controller
	SET CPU URH70		Unibus, I/O map with 22b addressing,
				22b unmapped RH70 controller
	SET CPU Q22		Qbus, no I/O map, 22b addressing
	SET CPU NOCIS		disable CIS instructions (default)
	SET CPU CIS		enable CIS instructions
	SET CPU 16K		set memory size = 16KB
	SET CPU 32K		set memory size = 32KB
	SET CPU 48K		set memory size = 48KB
	SET CPU 64K		set memory size = 64KB
	SET CPU 96K		set memory size = 96KB
	SET CPU 128K		set memory size = 128KB
	SET CPU 192K		set memory size = 192KB
	SET CPU 256K		set memory size = 256KB
	SET CPU 384K		set memory size = 384KB
	SET CPU 512K		set memory size = 512KB
	SET CPU 768K		set memory size = 768KB
	SET CPU 1024K (or 1M)	set memory size = 1024KB
	SET CPU 2048K (or 2M)	set memory size = 2048KB
	SET CPU 3072K (or 3M)	set memory size = 3072KB
	SET CPU 4096K (or 4M)	set memory size = 4096KB

The CPU implements a show command to display the I/O address space map:

	SHOW CPU IOSPACE	show I/O space address map

If memory size is being reduced, and the memory being truncated contains
non-zero data, the simulator asks for confirmation.  Data in the truncated
portion of memory is lost.  Initial memory size is 256KB.  If memory size
is being increased to more than 256KB, or the bus structue is being changed,
the simulator asks whether it should disable peripherals that can't run
in the current bus structure.

DMA peripherals function differently, depending on whether the CPU is
configured for 18B, URH11, URH70, or 22B addressing and I/O:

	peripheral	18B	URH11	URH70	22B

	RK		18b	18b	18b	won't work, disabled
	HK		18b	18b	18b	SC02/C 22b, works
						only with Ultrix-11
	RL		18b	18b	18b	22b RLV12
	RP		18b	18b	22b	22b third party
	RQ		18b	18b	18b	22b RQDX3
	RY		18b	18b	18b	won't work, disabled
	TC		18b	18b	18b	won't work, disabled
	TM		18b	18b	18b	won't work, disabled
	TS		18b	18b	18b	22b TSV05
	TQ		18b	18b	18b	22b TQK50
	XQ		18b	won't work,	22b DELQA
				disabled
	XU		18b	18b	18b	won't work, disabled

Non-DMA peripherals work the same in all configurations.  Unibus-only
peripherals should be disabled in a Qbus (22B) configuration with more
than 256KB of memory, and Qbus-only peripherals should be disabled in
a Unibus (URH11 or URH70) configuration with more than 256KB of memory.

These switches are recognized when examining or depositing in CPU memory:

	-v			interpret address as virtual
	-d			if mem mgt enabled, force data space
	-k			if mem mgt enabled, force kernel mode
	-s			if mem mgt enabled, force supervisor mode
	-u			if mem mgt enabled, force user mode
	-p			if mem mgt enabled, force previous mode

CPU registers include the visible state of the processor as well as the
control registers for the interrupt system.

	name		size	comments

	PC		16	program counter
	R0..R5		16	R0..R5, current register set
	SP		16	stack pointer, current mode
	R00..R05	16	R0..R5, register set 0
	R10..R15	16	R0..R5, register set 1
	KSP		16	kernel stack pointer
	SSP		16	supervisor stack pointer
	USP		16	user stack pointer
	PSW		16	processor status word
	  CM		2	  current mode, PSW<15:14>
	  PM		2	  previous mode, PSW<13:12>
	  RS		2	  register set, PSW<11>
	  IPL		3	  interrupt priority level, PSW<7:5>
	  T		1	  trace bit, PSW<4>
	  N		1	  negative flag, PSW<3>
	  Z		1	  zero flag, PSW<2>
	  V		1	  overflow flag, PSW<1>
	  C		1	  carry flag, PSW<0>
	SR		16	front panel switches
	DR		16	front panel display
	MEMERR		16	memory error register
	CCR		16	cache control register
	MAINT		16	maintenance register
	HITMISS		16	hit/miss register
	CPUERR		16	CPU error register
	PIRQ		16	programmed interrupt requests
	FAC0H..FAC5H	32	FAC0..FAC5, high 32 bits
	FAC0L..FAC5L	32	FAC0..FAC5, low 32 bits
	FPS		16	floating point status
	FEA		16	floating exception address
	FEC		4	floating exception code
	MMR0..3		16	memory management registers 0..3
	{K/S/U}{I/D}{PAR/PDR}{0..7}
			16	memory management registers
	UBMAP[0:63]	16	Unibus map registers
	INT		32	interrupt pending flags
	TRAP		18	trap pending flags
	WAIT		0	wait state flag
	WAIT_ENABLE	0	wait state enable flag
	STOP_TRAPS	18	stop on trap flags
	STOP_VECA	1	stop on read abort in trap or interrupt
	STOP_SPA	1	stop on stack push abort in trap or interrupt
	PCQ[0:63]	16	PC prior to last jump, branch, or interrupt;
				most recent PC change first
	WRU		8	interrupt character

2.2 I/O Device Addressing

PDP-11 I/O space is not large enough to allow all possible devices to be
configured simultaneously at fixed addresses.  Instead, many devices have
floating addresses; that is, the assigned device address depends on the
presense of other devices in the configuration:

	DZ11		all instances have floating addresses
	RL11		first instance has fixed address, rest floating
	RX11/RX211	first instance has fixed address, rest floating
	DEUNA/DELUA	first instance has fixed address, rest floating
	MSCP disk	first instance has fixed address, rest floating
	TMSCP tape	first instance has fixed address, rest floating

To maintain addressing consistency as the configuration changes, the
simulator implements DEC's standard I/O address and vector autoconfiguration
algorithms for devices DZ, RL, RX, RY, XU, RQ, and TQ.  This allows the
user to enable or disable devices without needing to manage I/O addresses
and vectors.  For example, if RY is enabled while RX is present, RY is
assigned an I/O address in the floating I/O space range; but if RX is
disabled and then RY is enabled, RY is assigned the fixed "first instance"
I/O address for floppy disks.

Autoconfiguration cannot solve address conflicts between devices with
overlapping fixed addresses.  For example, with default I/O page addressing,
the PDP-11 can support either a TM11 or a TS11, but not both, since they use
the same I/O addresses.

In addition to autoconfiguration, most devices support the SET ADDRESS
command, which allows the I/O page address of the device to be changed,
and the SET VECTOR command, which allows the vector of the device to be
changed.  Explicitly setting the I/O address of a device which normally
uses autoconfiguration DISABLES autoconfiguration for that device and for
the entire system.  As a consequence, the user may have to manually configure
all other autoconfigured devices, because the autoconfiguration algorithm
no longer recognizes the explicitly configured device.  A device can be
reset to autoconfigure with the SET <device> AUTOCONFIGURE command.  Auto-
configuration can be restored for the entire system with the SET CPU
AUTOCONFIGURE command.

The current I/O map can be displayed with the SHOW CPU IOSPACE command.
Addresses that have set by autoconfiguration are marked with an asterisk (*). 

All devices support the SHOW ADDRESS and SHOW VECTOR commands, which display
the device address and vector, respectively.

2.3 Programmed I/O Devices

2.3.1 PC11 Paper Tape Reader (PTR)

The paper tape reader (PTR) reads data from a disk file.  The POS
register specifies the number of the next data item to be read.  Thus,
by changing POS, the user can backspace or advance the reader.

The paper tape reader implements these registers:

	name		size	comments

	BUF		8	last data item processed
	CSR		16	control/status register
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	BUSY		1	busy flag (CSR<11>)
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	POS		32	position in the input file
	TIME		24	time from I/O initiation to interrupt
	STOP_IOE	1	stop on I/O error

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	out of tape

	end of file	1	report error and stop
			0	out of tape

	OS I/O error	x	report error and stop

2.3.2 PC11 Paper Tape Punch (PTP)

The paper tape punch (PTP) writes data to a disk file.  The POS
register specifies the number of the next data item to be written. 
Thus, by by changing POS, the user can backspace or advance the punch.

The paper tape punch implements these registers:

	name		size	comments

	BUF		8	last data item processed
	CSR		16	control/status register
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	POS		32	position in the output file
	TIME		24	time from I/O initiation to interrupt
	STOP_IOE	1	stop on I/O error

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	out of tape

	OS I/O error	x	report error and stop

2.3.3 DL11 Terminal Input (TTI)

The terminal interfaces (TTI, TTO) can be set to one of two modes:
7B or 8B.  In 7B mode, input and output characters are masked  to 7
bits.  In 8B mode, characters are not modified.  Changing the mode
of either interface changes both.  The default mode is 8B.

The terminal input (TTI) polls the console keyboard for input.  It
implements these registers:

	name		size	comments

	BUF		8	last data item processed
	CSR		16	control/status register
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	POS		32	number of characters input
	TIME		24	keyboard polling interval

2.3.4 DL11 Terminal Output (TTO)

The terminal output (TTO) writes to the simulator console window.  It
implements these registers:

	name		size	comments

	BUF		8	last data item processed
	CSR		16	control/status register
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	POS		32	number of characters input
	TIME		24	time from I/O initiation to interrupt

2.3.5 LP11 Line Printer (LPT)

The line printer (LPT) writes data to a disk file.  The POS register
specifies the number of the next data item to be written.  Thus,
by changing POS, the user can backspace or advance the printer.

The line printer implements these registers:

	name		size	comments

	BUF		8	last data item processed
	CSR		16	control/status register
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	POS		32	position in the output file
	TIME		24	time from I/O initiation to interrupt
	STOP_IOE	1	stop on I/O error

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	out of paper

	OS I/O error	x	report error and stop

2.3.6 Line-Time Clock (CLK)

The line-time clock (CLK) frequency can be adjusted as follows:

	SET CLK 60HZ		set frequency to 60Hz
	SET CLK 50HZ		set frequency to 50Hz

The default is 60Hz.

The line-time clock implements these registers:

	name		size	comments

	CSR		16	control/status register
	INT		1	interrupt pending flag
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	TIME		24	clock interval

The line-time clock autocalibrates; the clock interval is adjusted up
or down so that the clock tracks actual elapsed time.

2.3.7 Programmable Clock (PCLK)

The programmable clock (PCLK) line frequency can be adjusted as follows:

	SET PCLK 60HZ		set frequency to 60Hz
	SET PCLK 50HZ		set frequency to 50Hz

The default is 60Hz.

The programmable clock implements these registers:

	name		size	comments

	CSR		16	control/status register
	CSB		16	count set buffer
	CNT		16	current count
	INT		1	interrupt pending flag
	OVFL		1	overflow (error) flag (CSR<15>)
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	UPDN		1	up/down count mode (CSR<4>)
	MODE		1	single/repeat mode (CSR<3>)
	RUN		1	clock run (CSR<0>)
	TIME[0..3]	32	clock interval, rates 0..3
	TPS[0..3]	32	ticks per second, rates 0..3

The programmable clock autocalibrates; the clock interval is adjusted
up or down so that the clock tracks actual elapsed time. Operation at
the highest clock rate (100Khz) is not recommended.  The programmable
clock is disabled by default.

2.4 Floppy Disk Drives

2.4.1 RX11/RX01 Floppy Disk (RX)

RX11 options include the ability to set units write enabled or write locked:

	SET RXn LOCKED		set unit n write locked
	SET RXn WRITEENABLED	set unit n write enabled

The RX11 supports the BOOT command.

The RX11 implements these registers:

	name		size	comments

	RXCS		12	status
	RXDB		8	data buffer
	RXES		8	error status
	RXERR		8	error code
	RXTA		8	current track
	RXSA		8	current sector
	STAPTR		3	controller state
	BUFPTR		3	buffer pointer
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	TR		1	transfer ready flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	DONE		1	device done flag (CSR<5>)
	CTIME		24	command completion time
	STIME		24	seek time, per track
	XTIME		24	transfer ready delay
	STOP_IOE	1	stop on I/O error
	SBUF[0:127]	8	sector buffer array

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	disk not ready

RX01 data files are buffered in memory; therefore, end of file and OS
I/O errors cannot occur.

2.4.2 RX211/RX02 Floppy Disk (RY)

RX211 options include the ability to set units write enabled or write
locked, single or double density, or autosized:

	SET RYn LOCKED		set unit n write locked
	SET RYn WRITEENABLED	set unit n write enabled
	SET RYn SINGLE		set unit n single density
	SET RYn DOUBLE		set unit n double density (default)
	SET RYn AUTOSIZE	set unit n autosized

The RX211 supports the BOOT command.  The RX211 will not function
properly in a Qbus (22B) system with more than 256KB of memory.

The RX211 implements these registers:

	name		size	comments

	RYCS		16	status
	RYBA		16	buffer address
	RYWC		8	word count
	RYDB		16	data buffer
	RYES		12	error status
	RYERR		8	error code
	RYTA		8	current track
	RYSA		8	current sector
	STAPTR		4	controller state
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	TR		1	transfer ready flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	DONE		1	device done flag (CSR<5>)
	CTIME		24	command completion time
	STIME		24	seek time, per track
	XTIME		24	transfer ready delay
	STOP_IOE	1	stop on I/O error
	SBUF[0:255]	8	sector buffer array

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	disk not ready

RX02 data files are buffered in memory; therefore, end of file and OS
I/O errors cannot occur.

2.5 Cartridge Disk Drives

2.5.1 RK11/RK05 Cartridge Disk (RK)

RK11 options include the ability to make units write enabled or write
locked:

	SET RKn LOCKED		set unit n write locked
	SET RKn WRITEENABLED	set unit n write enabled

Units can also be set ONLINE or OFFLINE.  The RK11 supports the BOOT
command.  The RK11 will not function properly in a Qbus (22B) system
with more than 256KB of memory.

The RK11 implements these registers:

	name		size	comments

	RKCS		16	control/status
	RKDA		16	disk address
	RKBA		16	memory address
	RKWC		16	word count
	RKDS		16	drive status
	RKER		16	error status
	INTQ		9	interrupt queue
	DRVN		3	number of last selected drive
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	INT		1	interrupt pending flag
	STIME		24	seek time, per cylinder
	RTIME		24	rotational delay
	STOP_IOE	1	stop on I/O error

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	disk not ready

	end of file	x	assume rest of disk is zero

	OS I/O error	x	report error and stop

2.5.2 RK611/RK06,RK07 Cartridge Disk (HK)

RK611 options include the ability to set units write enabled or write
locked, to set the drive size to RK06, RK07, or autosize, and to write
a DEC standard 044 compliant bad block table on the last track:

	SET HKn LOCKED		set unit n write locked
	SET HKn WRITEENABLED	set unit n write enabled
	SET HKn RK06		set size to RK06
	SET HKn RK07		set size to RK07
	SET HKn AUTOSIZE	set size based on file size at attach
	SET HKn BADBLOCK	write bad block table on last track

The size options can be used only when a unit is not attached to a file.
The bad block option can be used only when a unit is attached to a file.
Units can be set ONLINE or OFFLINE.  The RK611 supports the BOOT command.
The RK611 will not function properly in a Qbus (22B) system with more
than 256KB of memory using standard DEC software.  The simulator implements
a third-party extension of addressing capability to 22b; this is only
supported by Ultrix-11.

The RK611 implements these registers:

	name		size	comments

	HKCS1		16	control/status 1
	HKWC		16	word count
	HKBA		16	bus address
	HKDA		16	desired surface, sector
	HKCS2		16	control/status 2
	HKDS[0:7]	16	drive status, drives 0-7
	HKER[0:7]	16	drive errors, drives 0-7
	HKDB[0:2]	16	data buffer silo
	HKDC		16	desired cylinder
	HKOF		8	offset
	HKMR		16	maintenance register
	HKSPR		16	spare register
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	DONE		1	device done flag (CSR1<7>)
	IE		1	interrupt enable flag (CSR1<6>)
	STIME		24	seek time, per cylinder
	RTIME		24	rotational delay
	STOP_IOE	1	stop on I/O error

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	disk not ready

	end of file	x	assume rest of disk is zero

	OS I/O error	x	report error and stop

2.5.3 RL11(V12)/RL01,RL02 Cartridge Disk (RL)

RL11 options include the ability to set units write enabled or write
locked, to set the drive size to RL01, RL02, or autosize, and to write
a DEC standard 044 compliant bad block table on the last track:

	SET RLn LOCKED		set unit n write locked
	SET RLn WRITEENABLED	set unit n write enabled
	SET RLn RL01		set size to RL01
	SET RLn RL02		set size to RL02
	SET RLn AUTOSIZE	set size based on file size at attach
	SET RLn BADBLOCK	write bad block table on last track

The size options can be used only when a unit is not attached to a file.
The bad block option can be used only when a unit is attached to a file.
Units can be set ONLINE or OFFLINE.  The RL11 supports the BOOT command.
In an 18B or Unibus system, the RL behaves like an RL11 with 18b
addressing; in a Qbus (22B) system, the RL behaves like the RLV12 with
22b addressing.

The RL11 implements these registers:

	name		size	comments

	RLCS		16	control/status
	RLDA		16	disk address
	RLBA		16	memory address
	RLBAE		6	memory address extension (RLV12)
	RLMP..RLMP2	16	multipurpose register queue
	INT		1	interrupt pending flag
	ERR		1	error flag (CSR<15>)
	DONE		1	device done flag (CSR<7>)
	IE		1	interrupt enable flag (CSR<6>)
	STIME		24	seek time, per cylinder
	RTIME		24	rotational delay
	STOP_IOE	1	stop on I/O error

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	disk not ready

	end of file	x	assume rest of disk is zero

	OS I/O error	x	report error and stop

2.6 RM02/03/05/80, RP04/05/06/07 Disk Pack Drives (RP)

The RP controller implements a "Massbus style" 22b direct interface
for large disk drives.  It is more abstract than other device simulators,
with just enough detail to run operating system drivers.  In addition,
the RP controller conflates the details of the RM series controllers
with the RP series controllers, although there were detailed differences.

RP options include the ability to set units write enabled or write
locked, to set the drive type to one of six disk types, or autosize,
and to write a DEC standard 044 compliant bad block table on the last
track:

	SET RPn LOCKED		set unit n write locked
	SET RPn WRITEENABLED	set unit n write enabled
	SET RPn RM03		set type to RM03
	SET RPn RM05		set type to RM05
	SET RPn RM80		set type to RM80
	SET RPn RP04		set type to RP04
	SET RPn RP06		set type to RP06
	SET RPn RP07		set type to RP07
	SET RPn AUTOSIZE	set type based on file size at attach
	SET RPn BADBLOCK	write bad block table on last track

The type options can be used only when a unit is not attached to a file.
The bad block option can be used only when a unit is attached to a file.
Units can be set ONLINE or OFFLINE.  The RP controller supports the
BOOT command.  In a Unibus system, the RP can implement either 18b
(RH11) addressing or 22b (RH70) addressing.  In a Qbus (22B) system,
the RP always implements 22b addressing.

The RP controller implements these registers:

	name		size	comments

	RPCS1		16	control/status 1
	RPWC		16	word count
	RPBA		16	bus address
	RPDA		16	desired surface, sector
	RPCS2		16	control/status 2
	RPDS[0:7]	16	drive status, drives 0-7
	RPER1[0:7]	16	drive errors, drives 0-7
	RPOF		16	offset
	RPDC		16	desired cylinder
	RPER2		16	error status 2
	RPER3		16	error status 3
	RPEC1		16	ECC syndrome 1
	RPEC2		16	ECC syndrome 2
	RPMR		16	maintenance register
	RPDB		16	data buffer
	RPBAE		6	bus address extension
	RPCS3		16	control/status 3
	IFF		1	transfer complete interrupt request flop
	INT		1	interrupt pending flag
	SC		1	special condition (CSR1<15>)
	DONE		1	device done flag (CSR1<7>)
	IE		1	interrupt enable flag (CSR1<6>)
	STIME		24	seek time, per cylinder
	RTIME		24	rotational delay
	STOP_IOE	1	stop on I/O error

Error handling is as follows:

	error	     STOP_IOE	processed as

	not attached	1	report error and stop
			0	disk not ready

	end of file	x	assume rest of disk is zero

	OS I/O error	x	report error and stop

2.7 RQDX3 MSCP Disk Controllers (RQ, RQB, RQC, RQD)

The simulator implements four MSCP disk controllers, RQ, RQB, RQC, RQD.
Initially, RQB, RQC, and RQD are disabled.  Each RQ controller simulates
an RQDX3 MSCP disk controller.  RQ options include the ability to set
units write enabled or write locked, and to set the drive type to one
of many disk types:

	SET RQn LOCKED		set unit n write locked
	SET RQn WRITEENABLED	set unit n write enabled
	SET RQn RX50		set type to RX50
	SET RQn RX33		set type to RX33
	SET RQn RD51		set type to RD51
	SET RQn RD52		set type to RD52
	SET RQn RD53		set type to RD53
	SET RQn RD54		set type to RD54
	SET RQn RD31		set type to RD31
	SET RQn RA82		set type to RA82
	SET RQn RA72		set type to RA72
	SET RQn RA90		set type to RA90
	SET RQn RA92		set type to RA92
	SET RQn RRD40		set type to RRD40 (CD ROM)
	SET RQn RAUSER{=n}	set type to RA81 with n LBNs

The type options can be used only when a unit is not attached to a file.
RAUSER is a "user specified" disk; the user can specify the size of the
disk in logical block numbers (LBN's, 512 bytes each).  The minimum size
is 50MB; the maximum size is 2GB.

Units can also be set ONLINE or OFFLINE.  Each RQ controller supports the
BOOT command.  In a Unibus system, an RQ supports 18b addressing.  In
a Qbus (22B) system, an RQ supports 22b addressing.

Each RQ controller implements the following special SHOW commands:

	SHOW RQn TYPE		show drive type
	SHOW RQ RINGS		show command and response rings
	SHOW RQ FREEQ		show packet free queue
	SHOW RQ RESPQ		show packet response queue
	SHOW RQ UNITQ		show unit queues
	SHOW RQ ALL		show all ring and queue state
	SHOW RQn UNITQ		show unit queues for unit n

Each RQ controller implements these registers:

	name		size	comments

	SA		16	status/address register
	S1DAT		16	step 1 init host data
	CQBA		22	command queue base address
	CQLNT		8	command queue length
	CQIDX		8	command queue index
	RQBA		22	request queue base address
	RQLNT		8	request queue length
	RQIDX		8	request queue index
	FREE		5	head of free packet list
	RESP		5	head of response packet list
	PBSY		5	number of busy packets
	CFLGS		16	controller flags
	CSTA		4	controller state
	PERR		9	port error number
	CRED		5	host credits
	HAT		17	host available timer
	HTMO		17	host timeout value
	CPKT[0:3]	5	current packet, units 0-3
	PKTQ[0:3]	5	packet queue, units 0-3
	UFLG[0:3]	16	unit flags, units 0-3
	INT		1	interrupt request
	ITIME		1	response time for initialization steps
				(except for step 4)
	QTIME		24	response time for 'immediate' packets
	XTIME		24	response time for data transfers
	PKTS[33*32]	16	packet buffers, 33W each,
				32 entries

Some DEC operating systems, notably RSX11M/M+, are very sensitive to
the timing parameters.  Changing the default values may cause M/M+ to
crash on boot or to hang during operation.

Error handling is as follows:

	error	     		processed as

	not attached		disk not ready

	end of file		assume rest of disk is zero

	OS I/O error		report error and stop

2.8 TC11/TU56 DECtape (DT)

DECtapes drives are numbered 1-8; in the simulator, drive 8 is unit 0.
DECtape options include the ability to make units write enabled or write
locked.

	SET DTn LOCKED		set unit n write locked
	SET DTn WRITEENABLED	set unit n write enabled

Units can be set ONLINE or OFFLINE.  The TC11 supports the BOOT command.
The TC11 will not function properly in a 22B (Qbus) system with more
than 256KB of memory.

The TC11 supports supports PDP-8 format, PDP-11 format, and 18b format
DECtape images.  ATTACH tries to determine the tape format from the DECtape
image; the user can force a particular format with switches:

	-r			PDP-8 format
	-s			PDP-11 format
	-t			18b format

The DECtape controller is a data-only simulator; the timing and mark
track, and block header and trailer, are not stored.  Thus, the WRITE
TIMING AND MARK TRACK function is not supported; the READ ALL function
always returns the hardware standard block header and trailer; and the
WRITE ALL function dumps non-data words into the bit bucket.

The TC controller implements these registers:

	name		size	comments

	TCST		16	status register
	TCCM		16	command register
	TCWC		16	word count register
	TCBA		16	bus address register
	TCDT		16	data register
	INT		1	interrupt pending flag
	ERR		1	error flag
	DONE		1	done flag
	IE		1	interrupt enable flag
	CTIME		31	time to complete transport stop
	LTIME		31	time between lines
	DCTIME		31	time to decelerate to a full stop
	SUBSTATE	2	read/write command substate
	POS[0:7]	32	position, in lines, units 0-7
	STATT[0-7]	31	unit state, units 0-7
	STOP_OFFR	1	stop on off-reel error

It is critically important to maintain certain timing relationships
among the DECtape parameters, or the DECtape simulator will fail to
operate correctly.

	- LTIME must be at least 6
	- DCTIME needs to be at least 100 times LTIME

Acceleration time is set to 75% of deceleration time.

2.9 Magnetic Tape Controllers
	
2.9.1 TM11 Magnetic Tape (TM)

TM options include the ability to make units write enabled or write
locked.

	SET TMn LOCKED		set unit n write locked
	SET TMn WRITEENABLED	set unit n write enabled

Units can be set ONLINE or OFFLINE.

The TM11 supports the BOOT command.  The bootstrap supports both original
and DEC standard boot formats.  Originally, a tape bootstrap read and
executed the first record on tape.  To allow for ANSI labels, the DEC
standard bootstrap skipped the first record and read and executed the
second.  The DEC standard is the default; to bootstrap an original format
tape, use the -o switch.

The TM11 will not function properly in a Qbus (22B) system with more
than 256KB of memory

The TM controller implements these registers:

	name		size	comments

	MTS		16	status
	MTC		16	command
	MTCMA		16	memory address
	MTBRC		16	byte/record count
	INT		1	interrupt pending flag
	ERR		1	error flag
	DONE		1	device done flag
	IE		1	interrupt enable flag
	STOP_IOE	1	stop on I/O error
	TIME		24	delay
	UST[0:7]	16	unit status, units 0-7
	POS[0:7]	32	position, units 0-7

Error handling is as follows:

	error			processed as

	not attached		tape not ready; if STOP_IOE, stop

	end of file		bad tape

	OS I/O error		parity error; if STOP_IOE, stop

2.9.2 TS11/TSV05 Magnetic Tape (TS)

The TS actually implements the TSV05, with 22-bit addressing, but will
work with TS11 drivers.  TS options include the ability to make the unit
write enabled or write locked.

	SET TS LOCKED		set unit write locked
	SET TS WRITEENABLED	set unit write enabled

The TS11 supports the BOOT command.  The bootstrap supports only DEC
standard boot formats.  To allow for ANSI labels, the DEC standard
bootstrap skipped the first record and read and executed the second.
In a Unibus system, the TS behaves like the TS11 and implements 18b
addresses.  In a Qbus (22B) system, the TS behaves like the TSV05
and implements 22b addresses.

The TS controller implements these registers:

	name		size	comments

	TSSR		16	status register
	TSBA		16	bus address register
	TSDBX		16	data buffer extension register
	CHDR		16	command packet header
	CADL		16	command packet low address or count
	CADH		16	command packet high address
	CLNT		16	command packet length
	MHDR		16	message packet header
	MRFC		16	message packet residual frame count
	MXS0		16	message packet extended status 0
	MXS1		16	message packet extended status 1
	MXS2		16	message packet extended status 2
	MXS3		16	message packet extended status 3
	MXS4		16	message packet extended status 4
	WADL		16	write char packet low address
	WADH		16	write char packet high address
	WLNT		16	write char packet length
	WOPT		16	write char packet options
	WXOPT		16	write char packet extended options
	ATTN		1	attention message pending
	BOOT		1	boot request pending
	OWNC		1	if set, tape owns command buffer
	OWNM		1	if set, tape owns message buffer
	TIME		24	delay
	POS		32	position

Error handling is as follows:

	error			processed as

	not attached		tape not ready

	end of file		bad tape

	OS I/O error		fatal tape error

2.9.3 TQK50 TMSCP Disk Controller (TQ)

The TQ controller simulates the TQK50 TMSCP disk controller.  TQ options
include the ability to set units write enabled or write locked, and to
specify the controller type and tape length:

	SET TQn LOCKED		set unit n write locked
	SET TQn WRITEENABLED	set unit n write enabled
	SET TQ TK50		set controller type to TK50
	SET TQ TK70		set controller type to TK70
	SET TQ TU81		set controller type to TU81
	SET TQ TKUSER{=n}	set controller type to TK50 with
				tape capacity of n MB

User-specified capacity must be between 50 and 2000 MB.

The TQ controller supports the BOOT command.   In a Unibus system, the
TQ supports 18b addressing.  In a Qbus (22B) system, the TQ supports
22b addressing.

The TQ controller implements the following special SHOW commands:

	SHOW TQ TYPE		show controller type
	SHOW TQ RINGS		show command and response rings
	SHOW TQ FREEQ		show packet free queue
	SHOW TQ RESPQ		show packet response queue
	SHOW TQ UNITQ		show unit queues
	SHOW TQ ALL		show all ring and queue state
	SHOW TQn UNITQ		show unit queues for unit n

The TQ controller implements these registers:

	name		size	comments

	SA		16	status/address register
	S1DAT		16	step 1 init host data
	CQBA		22	command queue base address
	CQLNT		8	command queue length
	CQIDX		8	command queue index
	RQBA		22	request queue base address
	RQLNT		8	request queue length
	RQIDX		8	request queue index
	FREE		5	head of free packet list
	RESP		5	head of response packet list
	PBSY		5	number of busy packets
	CFLGS		16	controller flags
	CSTA		4	controller state
	PERR		9	port error number
	CRED		5	host credits
	HAT		17	host available timer
	HTMO		17	host timeout value
	CPKT[0:3]	5	current packet, units 0-3
	PKTQ[0:3]	5	packet queue, units 0-3
	UFLG[0:3]	16	unit flags, units 0-3
	POS[0:3]	32	tape position, units 0-3
	OBJP[0:3]	32	object position, units 0-3
	INT		1	interrupt request
	ITIME		1	response time for initialization steps
				(except for step 4)
	QTIME		24	response time for 'immediate' packets
	XTIME		24	response time for data transfers
	PKTS[33*32]	16	packet buffers, 33W each,
				32 entries

Some DEC operating systems, notably RSX11M/M+, are very sensitive to
the timing parameters.  Changing the default values may cause M/M+ to
crash on boot or to hang during operation.

Error handling is as follows:

	error	     		processed as

	not attached		tape not ready

	end of file		end of medium

	OS I/O error		fatal tape error

2.10 Communications Devices

2.10.1 DZ11 Terminal Multiplexor (DZ)

The DZ11 is an 8-line terminal multiplexor.  Up to 4 DZ11's (32 lines)
are supported.  The number of lines can be changed with the command

	SET DZ LINES=n		set line count to n

The line count must be a multiple of 8, with a maximum of 32.

The DZ11 supports 8-bit input and output of characters.  8-bit output
may be incompatible with certain operating systems.  The command

	SET DZ 7B

forces output characters (only) to be masked to 7 bits.

The DZ11 supports logging on a per-line basis.  The command

	SET DZ LOG=line=filename

enables logging for the specified line to the indicated file.  The
command

	SET DZ NOLOG=line

disables logging for the specified line and closes any open log file.
Finally, the command

	SHOW DZ LOG

displays logging information for all DZ lines.

The terminal lines perform input and output through Telnet sessions
connected to a user-specified port.  The ATTACH command specifies
the port to be used:

	ATTACH {-am} DZ <port>	set up listening port

where port is a decimal number between 1 and 65535 that is not being used
for other TCP/IP activities.  The optional switch -m turns on the DZ11's
modem controls; the optional switch -a turns on active disconnects
(disconnect session if computer clears Data Terminal Ready).  Without
modem control, the DZ behaves as though terminals were directly connected;
disconnecting the Telnet session does not cause any operating system-
visible change in line status.

Once the DZ is attached and the simulator is running, the DZ will listen
for connections on the specified port.  It assumes that the incoming
connections are Telnet connections.  The connection remains open until
disconnected by the simulated program, the Telnet client, a SET DZ
DISCONNECT command, or a DETACH DZ command.

The SHOW DZ CONNECTIONS command displays the current connections to the DZ.
The SHOW DZ STATISTICS command displays statistics for active connections.
The SET DZ DISCONNECT=linenumber disconnects the specified line.

The DZ11 implements these registers:

	name		size	comments

	CSR[0:3]	16	control/status register, boards 0..3
	RBUF[0:3]	16	receive buffer, boards 0..3
	LPR[0:3]	16	line parameter register, boards 0..3
	TCR[0:3]	16	transmission control register, boards 0..3
	MSR[0:3]	16	modem status register, boards 0..3
	TDR[0:3]	16	transmit data register, boards 0..3
	SAENB[0:3]	1	silo alarm enabled, boards 0..3
	RXINT		4	receive interrupts, boards 3..0
	TXINT		4	transmit interrupts, boards 3..0
	MDMTCL		1	modem control enabled
	AUTODS		1	autodisconnect enabled

The DZ11 does not support save and restore.  All open connections are
lost when the simulator shuts down or the DZ is detached.

2.10.2 DHQ11 Terminal Multiplexor (VH)

The DHQ11 is an 8-line terminal multiplexor for Qbus systems.  Up
to 4 DHQ11's are supported.

The DHQ11 is a programmable asynchronous terminal multiplexor.  It
has two programming modes: DHV11 and DHU11.  The register sets are
compatible with these devices.  For transmission, the DHQ11 can be
used in either DMA or programmed I/O mode.  For reception, there
is a 256-entry FIFO for received characters, dataset status changes,
and diagnostic information, and a programmable input interrupt
timer (in DHU mode).  The device supports 16-, 18-, and 22-bit
addressing.  The DHQ11 can be programmed to filter and/or handle
XON/XOFF characters independently of the processor.  The DHQ11
supports programmable bit width (between 5 and 8) for the input
and output of characters.

The DHQ11 has a rocker switch for determining the programming mode.
By default, the DHV11 mode is selected, though DHU11 mode is
recommended for applications that can support it.  The VH controller
may be adjusted on a per controller basis as follows:

	SET VHn DHU		use the DHU programming mode and registers
	SET VHn DHV		use the DHV programming mode and registers

DMA output is supported.  In a real DHQ11, DMA is not initiated
immediately upon receipt of TX.DMA.START but is dependent upon some
internal processes.  The VH controller mimics this behavior by default.
It may be desirable to alter this and start immediately, though
this may not be compatible with all operating systems and diagnostics.
You can change the behavior of the VH controller as follows:

	SET VHn NORMAL		use normal DMA procedures
	SET VHn FASTDMA		set DMA to initiate immediately

The terminal lines perform input and output through Telnet sessions
connected to a user-specified port.  The ATTACH command specifies
the port to be used:

        ATTACH VH <port>	set up listening port
	DETACH VH

where port is a decimal number between 1 and 65535 that is not
being used for other TCP/IP activities.  This port is the point of
entry for al lines on all VH controllers.

Modem and auto-disconnect support may be set on an individual
controller basis.  The SET MODEM command directs the controller to
report modem status changes to the computer.  The SET HANGUP command
turns on active disconnects (disconnect session if computer clears
Data Terminal Ready).

	SET VHn [NO]MODEM	disable/enable modem control
	SET VHn [NO]HANGUP	disable/enable disconnect on DTR drop

Once the VH is attached and the simulator is running, the VH will
listen for connections on the specified port.  It assumes that the
incoming connections are Telnet connections.  The connection remains
open until disconnected by the simulated program, the Telnet client,
a SET VH DISCONNECT command, or a DETACH VH command.

The SHOW VH CONNECTIONS command displays the current connections to the VH.
The SHOW VH STATISTICS command displays statistics for active connections.
The SET VH DISCONNECT=linenumber disconnects the specified line.

The DHQ11 implements these registers, though not all can be examined
from SCP:

        name            size    comments

        CSR[0:3]        16      control/status register, boards 0..3
        RBUF[0:3]       16      receive buffer, boards 0..3
        LPR[0:3]        16      line parameter register, boards 0..3
        RXINT           4       receive interrupts, boards 3..0
        TXINT           4       transmit interrupts, boards 3..0
[more to be described...]

The DHQ11 does not support save and restore.  All open connections
are lost when the simulator shuts down or the VH is detached.

2.11 Ethernet Controllers

2.11.1 DELQA/DEQNA Qbus Ethernet Controllers (XQ, XQB)

The simulator implements two DELQA/DEQNA Qbus Ethernet controllers (XQ,
XQB).  Initially, XQ is enabled, and XQB is disabled.  Options allow
control of the MAC address, the controller mode, and the sanity timer.

	SET  XQ MAC=<mac-address>	ex. 08-00-2B-AA-BB-CC
        SHOW XQ MAC

These commands are used to change or display the MAC address.  <mac-address>
is a valid ethernet MAC, delimited by dashes or periods.  The controller
defaults to 08-00-2B-AA-BB-CC, which should be sufficient if there is
only one SIMH controller on your LAN.  Two cards with the same MAC address
will see each other's packets, resulting in a serious mess.

	SET  XQ TYPE={DEQNA|[DELQA]}
        SHOW XQ TYPE

These commands are used to change or display the controller mode. DELQA
mode is better and faster but may not be usable by older or non-DEC OS's.
Also, be aware that DEQNA mode is not supported by many modern OS's. The
DEQNA-LOCK mode of the DELQA card is emulated by setting the the controller
to DEQNA - there is no need for a separate mode.  DEQNA-LOCK mode behaves
exactly like a DEQNA, except for the operation of the VAR and MOP processing.

	SET  XQ SANITY={ON|[OFF]}
	SHOW XQ SANITY

These commands change or display the INITIALIZATION sanity timer (DEQNA
jumper W3/DELQA switch S4).  The INITIALIZATION sanity timer has a default
timeout of 4 minutes, and cannot be turned off, just reset.  The normal
sanity timer can be set by operating system software regardless of the
state of this switch.  Note that only the DEQNA (or the DELQA in DEQNA-
LOCK mode (=DEQNA)) supports the sanity timer - it is ignored by a DELQA
in Normal mode, which uses switch S4 for a different purpose.

	SET  XQ POLL={DEFAULT|4..2500}
	SHOW XQ POLL

These commands change or display the service polling timer.  The polling
timer is calibrated to run the service thread 200 times per second.  This
value can be changed to accomodate particular system requirements for
more (or less) frequent polling.

	SHOW XQ STATS

This command will display the accumulated statistics for the simulated
Ethernet controller.

To access the network, the simulated Ethernet controller must be attached
to a real Ethernet interface:

	ATTACH XQ0 {ethX|<device_name>}		ex. eth0 or /dev/era0
        SHOW XQ ETH

where X in 'ethX' is the number of the ethernet controller to attach, or
the real device name.  The X number is system dependant.  If you only have
one ethernet controller, the number will probably be 0. To find out what
your system thinks the ethernet numbers are, use the SHOW XQ ETH command.
The device list can be quite cryptic, depending on the host system, but
is probably better than guessing. If you do not attach the device, the
controller will behave as though the ethernet cable were unplugged.

XQ and XQB have the following registers:

	name		size	comments

	SA0		16	station address word 0
	SA1		16	station address word 1
	SA2		16	station address word 2
	SA3		16	station address word 3
	SA4		16	station address word 4
	SA5		16	station address word 5
	RBDL		32	receive buffer descriptor list
	XBDL		32	trans(X)mit buffer descriptor list
	CSR		16	control status register
	VAR		16	vector address register
	INT		1	interrupt request flag

One final note: because of it's asynchronous nature, the XQ controller is
not limited to the ~1.5Mbit/sec of the real DEQNA/DELQA controllers,
nor the 10Mbit/sec of a standard Ethernet.  Attach it to a Fast Ethernet
(100 Mbit/sec) card, and "Feel the Power!" :-)

2.11.2 DEUNA/DELUA Unibus Ethernet Controller (XU)

XU simulates the DEUNA/DELUA Unibus Ethernet controller.  Its operation
is analagous to the DELQA/DEQNA controller.

2.12 Symbolic Display and Input

The PDP-11 simulator implements symbolic display and input.  Display is
controlled by command line switches:

	-a			display as ASCII character
	-c			display as two character ASCII string
	-m			display instruction mnemonics

Input parsing is controlled by the first character typed in or by command
line switches:

	' or -a			ASCII character
	" or -c			two character ASCII string
	alphabetic		instruction mnemonic
	numeric			octal number

Instruction input uses standard PDP-11 assembler syntax.  There are sixteen
instruction classes:

class		operands		examples		comments

no operands	none			HALT, RESET
3b literal	literal, 0 - 7		SPL
6b literal	literal, 0 - 077	MARK
8b literal	literal, 0 - 0377	EMT, TRAP
register	register		RTS
sop		specifier		SWAB, CLR, ASL
reg-sop		register, specifier	JSR, XOR, MUL
fop		flt specifier		ABSf, NEGf
ac-fop		flt reg, flt specifier	LDf, MULf
ac-sop		flt reg, specifier	LDEXP, STEXP
ac-moded sop	flt reg, specifier	LDCif, STCfi
dop		specifier, specifier	MOV, ADD, BIC
cond branch	address			BR, BCC, BNE
sob		register, address	SOB
cc clear	cc clear instructions	CLC, CLV, CLZ, CLN	combinable
cc set		cc set instructions	SEC, SEV, SEZ, SEN	combinable

For floating point opcodes, F and D variants, and I and L variants, may be
specified regardless of the state of FPS.

The syntax for specifiers is as follows:

syntax		specifier	displacement	comments

Rn		0n		-
Fn		0n		-		only in flt reg classes
(Rn)		1n		-
@(Rn)		7n		0		equivalent to @0(Rn)
(Rn)+		2n		-
@(Rn)+		3n              -
-(Rn)		4n              -
@-(Rn)		5n              -
{+/-}d(Rn)	6n		{+/-}d
@{+/-}d(Rn)	7n		{+/-}d
#n		27		n
@#n		37		n
.+/-n		67		+/-n - 4
@.+/-n		77		+/-n - 4
{+/-}n		67		{+/-}n - PC - 4	if on disk, 37 and n
@{+/-}n		77		{+/-}n - PC - 4	if on disk, invalid
