RCA 1800 User manual

lnstruction Manual for the RCA
COSMAC Micromonitor CDP1 8S030
MPM-218 Sussested price $5.00
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Micromonitor CDP1 85030
for the RCA COSMAC
lnstruction Manual
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Information furnished by RCA is believed to be
accurate and reliable. However, no responsibility
is assumed by RCA for its use; nor for any in-
fringements of patents or other dghts of third
parties which may result from its use. No
license is granted by implication or otherwise
under any patent or patent rights of RCA.
'Irrtlenrark (s) Registcred@
Murt l (s) l{cgist rldl (s)
()opyright I978 by R()A Corporation
(All rights reserved under Pan-American Copyright Convention)
hinted in USA/I-78
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Foreword
tr-hen the Micromonitor is used with a COSMAC
Derelopment System CDPIBSOOS and the COSMAC
Floppr Disk System CDPI8SB0S, its capability can
:r considerably enhanced by utilization of the
\Iicromonitor Operating System CDPIBSB31. The
]licromonitor Operating System (MOPS) includes
rhe \IOPS diskette CDPIBSB3O, a UART Interface
\lc-rdule CDPIBSS0B, and a connecting cable CD-
Pllls5ll MOPS provides an extended set of
\licromonitor-type commands that allow the user to
,-,rnreniently switch Micromonitor commands and
:rspons€s to and from a variety of peripherals. It also
::or ides several commands which allow a degree of
a'rt..)mation in system debugging and testing. The
:lilization of the Micromonitor Operating System is
r',< rib€d in the RCA COSMAC Micromonitor
I )ptrating System (lltOPS) CDI'I8S{131 Users'
(,uitlr'. MIM.222.
.lhis manual assumes that the reader has a good
,,.,',rkirg knowledge of the CDPiB02 microprocessor,
..:ch as can be obtained from the User's Manual for
:he CDP1802 COSMAC Microprocessor' MPM-
- -. If the Micromonitor is used with a development
.', item. such as the Evaluation Kit or COSMAC
tttrelopment System, the appropriate manual for
::., ,ie svstems should also be studied before the
\1i' ronronitor is used.
The RCA CDP1BSO3O Micromonitor is a self-
contained, powerful debugging tool for use with any
system based on the CDPI802 Microprocessor. It
permits in-circuit debugging in real time so that both
hardware and soltware problems can be efficiently
screened. The Micromonitor is interposed between
the system under test and the system's CDPI802
CPU, giving the user control of both hardware in-
terfaces and exeeution of the user program. The
Micromonitor, although controlled by its own in-
ternal microprocessor, uses the microprocessor,
polver supply, clock, memory, and other components
of the system under test to run the user program.
Thus, it is not an emulator, but a monitor of system
performance. It has been designed to induce a
minimal effect on the system under test and provides
a reliable measure of true Bystern performance.
A repertoire of simple commands that can be
exercised from a selfcontained keyboard or a standard
external terminal provides control of program
execution and hardware interfaces. This comrnand
repertoire together with a system of user prompts for
providing positive feedback on system operation gives
the user a powerful tool for the detection of system
problems.
3

lnstruction Manual for the RCA COSMAC lvlicromonitor CDP185030 I
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Table of Contents
Foreword
Introduction
Installation and Initial Operation
Before Connecting the Micromonitor
Setup
Power Sequencing
Display Prompt
Further Checks
Micromonitor Self-Test Card
Notes on Use with CDS CDPI85004
Notes on Use with CDS II CDPI85005
Control Keys and System Operation
Basic Operating Controls
Cursor and Data Entry 1<--+1
Shift IGv (SH)
Memory Operations (M)
Register Operations
Register Mode (R)
Registers X and P (X-P) .
Interrupt Enable and Register T (IE-T)
Data Flag and Register D (F-D)
Q Output Line (Q)
Program Run Modes
Real Time Run ($P)
Single-lnstruction Cycle ($N)
Single Machine Cycle ($S)
Breakpoints
Manual Break (BK)
Break Conditions (BC)
Break Response
Data Logging (LOG)
Control of External Signals
Wait (WAIT)
Clear (CLR)
Interrupt (INT)
Direct Memory Access (DMAD (DMAO)
Reset Request (RR)
hhibit Request (IR)
Flag Lines (EFl ) (EF2) (EF3) (EF4)
Input Mode (IN)
Output Mode (OUT)
Control of External Options
External Memory (EXM)
Terminal Option (10) (30) (120)
Parameter Pass Feature
Operation of Micromonitor from Terminal
Command Syntax
Memory Operations
Register Operations
R Register
D Register
DF Flag
X Register
P Register
IE Flag
T Register
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lnstruction Manual for the RcA. cosMAC Micromonitor cDp1gs03o T
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kogram Run Modes
Real-Time Run
Single Instruction
Single Cycle
Breakpoints
Set Break Conditions
Clear Break Conditions
Data Lng
Control of External Signals
Wait
Clear
Interrupt
DMAIN
DMAOUT
Reset Requests
Inhibit Requests
FIag Lines
Input
Output
Additional Control Commands
External Memory
Micromonitor Keyboard
Terminal Operation
Break Response
Micromonitor llardware
How the Micromonitor Executes Instructions
Effects of System Clock
How the Micromonitor Gains Control
Register Save and Restore Operations
Instruction and Cycle Counting
Control of External Signals
External lnterfaces to the Micromonitor
External Break Input
External Memory
Terminal lnterface
Crystal Socket
Specifications
Example Session
Appendix A - RCA Micromonitor Keyboard Command Summary
Appendix B - RCA Micromonitor Terminal Command Summary
Appendix C - RCA COSMAC Microprocessor CDPI802 Instruction
Summary
Appendix
Appendix
Appendix
D - t ogic Diagrams for RCA COSMAC Micromonitor
F Transformer Connections for I l5- or 230-Volt
AC Operation
Page
24
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Appendix G - Instructions for Converting a Model 33 Teletype
Terminal from Half- to Full-Duplex Operation and
CDPI 8SO3O
E - Conneetor Pin Lists
from 60-mA to 20-mA Operation
Data Terminal-Micromonitor Connection
COSMAC Micromonitor Operating System
Appendix H -
Appendix I -Details
(MoPS)
CDPI85831
Appendix J - Operation of a Typical Developmental System

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lntroduct$on
The CDP1BSO3O Micromonitor offers a complete
set of debugging aids for CDP1BO2 systems. With it,
one can examine and alter a system's memory and all
the internal registers of the CPU, break on nine
different conditions, run programs in three different
modes, and control external signals to the CPU.
The Micromonitor can be operated from its built-in
kel board or from an external ASCII terminal. In its
simplest configuration the monitor is connected only
to the Eyetem under test as ehown in Fig. l. The
operator can then control the monitor from the built-
ir keyboard.
MICROMON I TOR SYSTE M
UNDER TEST
92CS- 29941
Fig 7 - Configuration for simple keyboard operation.
If a data terminal is available. it also can be used to
r'ontrol the monitor. In this way, as shown in Fig. 2,
the operator can retain a hard-copy record of the
,i.buuging session. Without making any changes in
its connection to the Monitor, the terminal can be
shared by another system. Fig. 3 for example, shows
how a COSMAC Development System may also use
the terminal.
MICROMON ITOR SYSTEM
UNDER TEST
92CS-2 9939
Fig. 3 - Data terminal shared by Micromonitor and CDS.
[henever the Micromonitor is being operated by
the built-in keyboard (as opposed to by the terminal),
the signals frorh the terminal are fed through the
Micromonitor to the CDS. As shown in Fig. 4, the
terminal can even be shared by the Syatem Under
Test. Refer to Appendix H.
TERMI NAL M ICROMONITOR SYSTEM
UNDER TEST
92C S - 29942
-ERMINAL
2 - Connection of external data terminal for
Micromonitor cantrol.
Fig. 4 - Data terminal shared by Micromonitor and
system under test.
For some applications, such as production testing,
it may be desirable to issue a predetermined set of
commands to the Micromonitor. In this case another
svstem can be used to control the Micromonitor via
SYSTEM
UNDER TEST
92CS-29940
TERMI NAL
FI
MICROMONiTOR

8
the terminal ilterface. as shorvn in the block diasram
,rf Fic. 5. For such applications. the \Iicrlrnonitor
( )Jieratins S\ :tem r\IOPS I CDP 1BSB31 *vould be a
TEFM NAL CONTRCLSYSTEM MICROMONITOR SYS1EM
(cos 6tc ) UNDER TEST
Fig. 5 - Micromonitor operated Ur r rrr'o)),:;:;-
consisting of hardware such as the COSMAC
Development System ll with Floppy Disk option
and using the software of the Micromonitor
Operating System (MOPS) CDPI 85831 -
helpful adjunct (See Micromonitor Op"f4rl-rg
System (MOPS) CDPISSS:}I UsersoGuide, MPM-
231 and Appendix I. Also, see Appendix J. Operation
of a Typical Developmental System. )
The many dif f erent conf igurations f or
Micromonitor usage make it applicable in the
laboratory for design, in the field for maintenance' or
in the factory for production testing. In addition, with
its single-cable connection and integral carrying case
it iB a highly Jxrrtable ingtmment.
lnstruction Manual for the RCA COSMAC lrilicromonitor CDPl85030
The advanced feattues of the Micromonitor allo*' it
to be incorporated into a s)'-ctem at anv stage of
,c\stem dereiopment. The external Memor-v socket
(see Fig. 6| allorvs memory to be added to the s1'stem
under test via the Micromonitor. For example, a
ROM system under development could be checked by
running the program from a CDP1BS205V1 4'
kiiobyte RAM rnodule plugged into the Memory
Socket.
The Micromonitor has three run modes, $P, $N,
and $S. $P mode runs the system in real time. $N
mode allows the operator to specify the nurnber of
in-qtructions to perform. $S rnode accepts a number of
cycles to exeoute. Neither $N nor $S runs in real time.
Other features of the Micromonitor are:
'I'wo rro<les of data trogging
Control of I/O devices
Tactile-response keyhoard with LED display
Terminal Interfacel
EIA or TTY
I10,300, 1200 baud
Tracking power supply over range of 4 to l1 volts
ll0/22A volt 50/60 hertz operation
Quick-ref erence abbreviated instructions
Sel{ contained
Microprocessor controlled
Minin.iatr effect on svstern under test
Self-test eard for verifir:ation ol Micromonitor
olxlrat;on
lG:
INSTRUCTION
MANUAL
TERMINAL
OUTPUT
CONNECTOR
aEXTERNAL
MEMORY
SOCKET
CPU
UNDER
TEST
TERMI NAL
INPUT
CONNECTOR \TO
SYSTEM
UNDER
TEST
REFERENCE
CARD
STAT U S
DISPLAY
EUILT.IN
KEYBOARD B
DISPLAY
92CS- 29652
6 - Major elements of RCA COSMAC Micromonitor
CDP78SO3O.
Fis.
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CRYSTAL
SOCKET

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lnstallation and lnitial Operation
This Chapter describes how the Micromonitor is
,nnected for testing a CDPIB02 Microprocessor'
:,a.ed s1'stem and gives the steps to be used for initial
:,eration.
Before Connecting
the Micromonitor
\ ferv simple tests should be made on the hardware
,l the system under test before it is hooked up to the
]1ir:romonitor. Only a few signals are required by the
\licromonitor to allow it to exercise the system under
'.rit. -A,lthough other problems may cauge the
)Iicromonitor to read or write data incorrectly, the
:-:eience of the signals listed below will indicate to the
]Iicromonitor that the CPU under test is obeying its
:. 'tructions,
- Check Vpp (pin 40) and Vqg (pin 16) for
appropriate voltage and Vgs (pin 20) for
ground.
I Check the cl<rck (pin I ) to rnake nure that it ig
running.
I Check that TPA (pin 34) and TPB (pin 33) are
being generated. TPB should always be
present when the clock is running unless the
processor is in the WAIT mode. TPA should
also be present except in the WAIT mode or
unless the processor ia idling in the LOAD
mode. A convenient way to get both pulses is
to put the processor in the LOAD mode and
senerate continuous DMA'OUT request$
rpins 2. 3. and 37 all low).
. Check the State Code lines (pins 5 and 6) for
normal operation,
Setup
With all power off, remove the CPU from the
system under test (SUT). Solder a 40-pin socket in
place of the CPU if one is not already there. The
Micromonitor is connected to the SUT through the
4O-conduetor cable supplied" Pin I is dr:noted hy a
not<:h in lhc <nrnrlr of tho r:uble tr:rntinutiong. ()n thrr
sockets of the Mioromonitor, pin I is adjacent to the
handle. Be rure to observe proper p<llaritiea whr:n
installing the connector and CPU.
Install the CPU in the Micromonitor socket labeled
CPU as shown in Fig. 7. Instail one end of the cable
in the Micromonitor socket labeled CABLE and the
other end in the empty CPU socket of the system
under test. It is recommended that the crystal of the
SUT also be moved to the Micromonitor, particularly
for systems operating at higher frequencies. The
crystal is inserted into the l4-pin socket labeled
CRYSTAL on the Micromonitor, one pin on each
side of the socket. The cryetal selection switch should
be prrt in the [N ponition to activate the socket. If the
crystal or system clock remains on the SUT, the
selector switch should be in the OUT position. For
additional information, see the Chapter Hardware
under the subheading "Crystal Socket".
Make any connections deeired to the External
Break Input, Memory Disable Output, or insert any
external memory card before turning power on. Also,
connect terminal inputs and output, if desired, at this
time. See the Chapter Hardware for a discussion of
these options.
Table I summarizes the set-up steps.
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10 lnstruction Manual for the RCA COSMAC Micromonitor CDP1BS030
Fig. 7 - Micromonitor connected to system under test.
1.
2.
3.
4.
5.
6.
7.
TABLE l. Check List of Steps Bequired Before
The Micromonitor is Turned On.
The 40-conductor cable should be connected properly
at both ends. Observe polarity!
The CDP1802 of the system under test should be in
the Micromonitor CPU socket.
Any connections to the External Break lnput, the
Memory Disable Output, or the Memory Card Socket
should be made.
The Crystal lN/OUT switch should be in the desired
position. lf the switch is in the up position (lN), a
crystal or oscillator should be connected to the 14-pin
socket of the Micromonitor.
lf a data terminal is used, it should be connected to
the Terminal connector. lf the Terminal Output is
used, it should also be connected.
Both the Micromonitor and the systern
should be plugged in.
Do not apply power to the system under
the Micromonitor is ON.
then turn off the Micromonitor. Never insert or
remove IC's with power on. It is recommended that
the Micromonitor and SUT both be plugged into a
common AC power distribution box.
Display Prompt
As a check that the connections are properly made,
after the Micromonitor and the SUT are turned on it
is helpful to push the Reset switch to display the eight
decimal points, as shown in Fig. B. (The center digit
under test
test unless
Fig. I * Micromonitor display prompt.
of the display is not used by the Micromonitor. ) This
display is the general user prompt and means that the
Micromonitor is mnning and is ready to accept &
*rmmand. The eight decimal points will reappear as
a prompt il an erroneous key is pressed, causing the
Micrornonitor to exit that command mode, or
whenever the Micromonitor is ready to accept
another command.
If the prompt does not appear after the Reset
switch is pushed, power should be shut off and the
connection-o rechecked. If the problem persists, refer
to the following sections "Frirther Checks" and
"Micromonitor Self-'fest Card. "
Power Sequencing
To avoid damage to either systern, the system
under test should never be on while the
Illicromonitor is off. First, turn on the
Micromonitor power switch, located near the
fuseholder; then, turn on the system under test.
To turn the power down, re verse the above
procedure. First turn o{f the system under test and
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I nstallation and lnitial Operation
Further Checks
.{Jter the Micromonitor is Reset, it extracts the
CPL registers before issuing its prompt. If any of the
.ignals mentinned in the aection "Before Connecting
rhe Micromonitor" are missing, the Micromonitor
,,ill "think" that the SUT is running very slowly. It
rn ill rvait for the CPU to execute a command and may
n",,er display a prompt. If the prompt does not ap'
:,par. diJconnect the Micromonitor, recheck the
.isnals listed above, and then, if needed' check the
\licromonitor stand'alone operation with the self'test
,-ard as described in the next section.
If the prompt does appear, make two simple tests
:,, r erify ihe integrity of the data bus and address bus.
Fir=t. examine Q by pressing SH and then Q. Azero
,: 1 should be displayed which should agree with the
,ndicating LFID on the Micromonitor. Toggle the
i:-1,lar with the ENT key. If a number other than
iir,) or one appears, there is a problem in the data
.{Jter the data bus has been verified' the address
t,.r-. can be checked with the $S command. Press $S
ard enter 0000 as the starting address. Press ENT
' --d {-}000 should be displayed in the address lield and
::. data byte at that location in the data field. If the
.i,lress is not 0000, there is a problem with the ad-
l-e.s lines. For example, an address of 0404 indicates
.:at address line A2 is shorted high. Note that the
-.;:-order address bits being displayed come from an
--.:.:nal latch in the Micromonitor. They are not
:, ...arilv rvhat the SUT sees. A short on the output
: :he SL T's address latch will not be detected by this
':h,rd.
T-:e same procedure should also be applied with an
,- l:..i FFFF to detect any bits shorted to ground
,- : '',, ith alternating bit patterns AAAA and 5555 to
-:: : bit lines shorted together.
Micromonitor Self'Test Card
r, o:['test card is supplied with the Micromonitor
' r.ii the user can verify some basic Micromonitor
- :: ',. oS . The card is set up to provide terminations
- : :.-.e lu-rrire connector cable to simulate signals
:rom a systern. The connections are shown in Fig9.
\lthough there is no memory on the test card, the
,lata bus is pulled high through 22-kilohm resistors so
:hat an.v "memory location" read will appear to
,,ntain an FF. Because FF is a valid instruction code
:,,r the CDPIB02 (Subtract Memory Immediate), the
;-r,)cessor can actually fetch and execute this in-
-:nrction from the non-existent memory.
Fig. 9 - Connection diagram for Micromonitor self-
test card.
The test card should be inserted in the Exteraral
Memory eocket (with the component side facing
front) and the free end of the 4O'conductor cable
plugged into the DIL socket. Be sure to observe
prop"r polarity. The Crystal InlOut switch should be
in ihe Out position. A CDPIS02 known to be good
must be in the Micromonitor CPU socket. Turn
po\trer on and push the Reset ewitch. The decimal
point prompt should appear. If it does not, the CPU
or the Micromonitor itsell may be defective. Also,
check to make sure that the oscillator on the test card
is operating. Then, recheek all of the signals listed in
the section "Before Connecting the Micromonitor."
Finallyr substitute a second CDPIB02 in the
Micromonitor CPU socket. The test card operates at
5 volts so that either a CDP1802D or CDPIB02CD
may be used. If the Micromonitor still fails to fisplay
a prompt, it is probably defective.
Once the prompt does appear, the Q mode
operation described previously shoulal be tried. In
that mode, a substantial portion of the Micromonitor
circuitry is exercised. Noting that SMI #FF to be
executed is equivalent to an ADI #0f will provide
some ideas foi further tests. For example, the break-
point logic can be teeted by setting a break on READ
irom location FFFF. First, set D to 00 and then do
$P0000. After about a second, the Micromonitor
should break. Check that P:00 D:00, and
R(0):0000. Try other break addregses as well.
The External Memory Select Signal can also be
tested because it is connected to EFl. Set EXM to I
and see if the indicator LED comes on. Also, program
a break on EFI and test it.
If the Micromonitor does not operate properly with
a CPU known to be good, it is suggested that the unit
be returned for repair. It is not advisable to attempt
EXTERNAL MEMORY
SELECT-P
CLOC K
f ! IOO kHz
cDPrBo2 voo
(socKEr) wa.lT
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12 lnstruction Manual for the RCA COSMAC Micromonitor CDP1B3030
sesaioa, sbould clear out this request by executing a
$Nl eommand.
to trouble*root the Micromonitor itsell becauee it ie a
very oomplex ED/stem and any modifications to the
ryEtem or unauthorized repairs may void the
t'srranty.
Notes on Use with
CDS CDP18SOO4
When the Micromonitor is used with the CDS
(ll)l'llls{X)4. trvo iteme chould be taken into con'
sideration. First, it should be noted that the RESET
button in the CDP1BSOO4 disables the CDPIBSOO4
oscillator eircuit. Consequently, if this oscillator
circuit is being used as the system clock, after power
on or alter the RESET button has been pressed' the
RUN U or RUN P button must be pressed to make
sure that the system has a clock.
Second, it should be noted that when RUN U or
RUN P is preseed, a DMA OUT request is generated
in the CDPIBSOO4 Eyotem 8E part of the normal
starting method. If the Micromonitor is in control,
this DMA request will remain until the system is
released with a $P, $N or $S command with IR:O.
The user, therefore, prior to beginning a debug
Notes on Use with
cDS lr cDPl85005
When the Micromonitor is used to debug a
program running nn the CDSII CDPlBS005 and u-se
iri to be made of the Micromonitor's External
Memory option, such as, for example, the 4-kilob-vte
RAM module CDP1BS205VI, the follon-ing
modifications must be made to the CDS II to allou'
the External Memory Select signal to disabie the
memory space in the CDS (See "External Memory"
on page 33 of the Mierornonitor Hardw.are section ).
1. Disconnect the *V line at pin 15 of each of the
four CDPl856's (U3, U4, U5, and U6) on the CPU
module CDPIBSI(12.
2. Connect the External Memory Deselect-N line
(pin A of the Micrornonitor's External Memory
Interface Connector) to pin 15 of the fotu CDPIS;':6's
in place of *V on the CFU module CDP18Sl02.
3. Connect the External Memory Deselect'N line
(pin A of the Micromonitor's External Memor.v
Interface Connector) to pin X of the Address Latch
and Bank Select module CDP185206 (MBDS-N).
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Control Keys and System Operation
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In this Chapter, the various keys used for control or
i;:a entn' are described along with the various modes
j .r !tem operation.
Basic Operating Controls
Cursor and Data Entry ( *>)
\lost command modes display more than one
: rmber at a time. l'or example, the Memory Addreris
:.,,de dislllays a memory address and ita contents.
f :e cursor is a set of decimal points indicating which
:.rmber or field is being addressed by the keyboard.
T,, move the cursor, press the <--+key. This key causes
::,- crrsor to toggle between the two fielda of the
; r. rlar . If there are more than two, the cursor moves
: the left. wrapping around to the right-hand when it
l:i: to the end.
To change a number on the display, move the
,,r.:or to that field and punch in the new number.
: i. nerv number is shilted into the right of the field.
I ht left-most number is lost.
Erample 8.0.0.0. c 4
in memorv mode, M(8000) contains a C4. If "1" is
: - ...er1. the display <:hanges to
0.0.0.1. F 8
\ote the right hand number changed to show the
r-:a at the new location,0001.
f,, enter data into the address field, a push of the
. . ke\. moves the cursor to the data field.
0001 F.8.
When a " l " is pressed, the following appears.
0001 8.1.
The new data (81) is written to location 0001 when
the ENT button is pressed, as described in the next
section. Prior to the pressing of EN'I, <lnly the
disllluy is altt:rrxl, not the or:tual datu kxrttion.
Note: All numbers ar(: to be in hex (addregs, data,
or operation numbers) for all Micromonitor com-
mands.
Sh"ift Key (SH)
Many of the Micromonitor's keys perform two
separate functions. To use the second function, the
shift key (SH) must be pressed prior to pressing the
function key. The display acknowledges the SH key
by showing a special prompt - every other decimal
point lighted. In the shift mode, pressing a control
key causes the Micromonitor to use the shifted
function (function printed on the case). This mode
can be used only iI the Micromonitor is in control.
Memory Operations (M)
The Memory Mode is used to examine and modify
memory. To enter the memory mode press the M key.
An address and the data at that address is displayed
as shown in Fig. 10. I'his mode can be used only if the
Micromonitor is in control.

14 lnstruction Manual for the RCA COSN'1AC i' :'o-onrtor CDPlBS030 I
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10
Register T (lE-T)
0. o. 0. 0. F I
ADDR ESS
FIELD DATA
FIELD
M(0000) = F8
Fig. 10 - Memory mode display.
The initial address displayed is usually 0000 when
this mode is entered. If a new address is entered, the
data field key automatically shows the contents of
that location. Pressing the ENT key entera the data in
the display field into the displayed address and then
increments the addrese by 1.
To enter a new number into a memory location,
move the cursor to the address field and enter the
desired location. Then, move the cursor to the data
field and enter the desired byte. FinallY, Press the
ENT key. The address is automatically incremented
and the contents of the new location shown.
To read the contents of a memory location, simply
enter the desired address (cursor in address field).
Pressing the ENT button increments past any
Iocation without changing the byte there if the display
is not altered. If the displayed data byte is
erroneously changed, pressing<-+ before ENT causes
the actual data at the displayed address to reappear.
Register Operations
Register Mode (R)
The Register mode is used to examine and modify
any of the 16 "R" registers of the CPU. To enter the
Register mode, press R. A register number and the
contents of that register is displayed as shown in Fig.
I l. This mode can be used only if the Micromonitor is
in control.
1 2 3 4 3.
The cursor app€an under the register numhrr
rvhich initiallv is usualh' 0, Operation in this mode i.
similar to the }Iemory mode. To read the contents r,f
a register. enter the desired register number. Pressins
the ENT kef increments the register number and the
contents oI the new register are displayed.
To change the contents of a register. move the
cursor to the data field and key in the desired
number. Pressing the ENT key causes the nerv
number to be written to the designated register. If ..-*
is pressed before ENT, the original contents rvill
reappear.
RegistersXandP(X-P)
In this mode the value of X and P can be examined
and modified. To enter the X-P mode, press the X-P
key. X and P are then displayed as shown in Fig. 12.
X =1 P =0
Fig. l2 - X-P made display.
The cursor starts under P. To change either X or P,
move the cursor to the correct field, enter the new
value, and press ENT. If <+ is pressed before ENT'
the original value returns and remains unaltered.
This mode can be used onlv if the Micromonitor is in
control.
tnterrupt Enable and
In this mode IE and T
modified. To enter this mode,
T. IE ancl T are displayed as
can be examined and
press StrI and then IE-
shown in Fig. 13. The
BEGISTER
Fig. ll * Registermodedisplay.
0 1. 0.
lE=0
Fig" l3 - lE-T mode display.
cursor starts under T. F-ither value can be changed by
moving the cursor to the appropriate digit, entering
the desired value. and pressing the ENT key. Only
values 0 or 1 are accepted for IE. If *-, is pressed
be{ore ENT, the original contents will reappear. Thig
motle r:un be ttsr,rl only if the Mir:rontonitor in in
control.
CONTENTS
OF BEGISTER
NUMBER
10.

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l.:-:.:i Keys and System Operation
Data FIag and Register D (F-D)
I: :ri= mode the value of DF and D of the CPU can
:,= .'r.:ri:-ned and altered. To enter this mode press F-
- LtF ard D are displayed as shown in Fig. 14. The
DF = 1 D = 82
Fig. 74 - F-D mode display.
-: r r itartS under D. Either value can be changed by
.-- i'-ri the cursor to the appropriate digit, entering
'-, . i..ired value, and pressing the ENT key. Note
: - " : D F can onl.v have the value I or 0. An attempt to
-r.r: :nv other value into DF is ignored. If *- is
::,..a1 before ENT, the original contents will
rn:: Fea-r. This mode can be used only if the
\1. r -,monitor is in control.
Q Output Line (Q)
Ihe Q llode is used to examine and modify the Q
i.:-flop of the CPU. To enter Q mode press SH then
,t f,-, toggle the value of Q, press ENT. An example
i :re Q displav is given in Fig. 15. Thiri mode doeg
1.
O=1
Fig. 15 - O mode display.
: -: .impl1' Iook at the Q output pin of the CPU, but
: e= a conditional branch on the state of Q as part of a
::.rpier softryare procedure. If the CPU is defective
: 3 i\stem fault is preventing proper execution of
:-oi:uctions, a value other than 0 or 1 may be shown
' - t r. providing useful debugging information. This
:. ,ie can be used only i{ the Micromonitor is in
: tr,-rl.
Program Run Modes
l'rosrams may be run either in real time from a
-l.*cilied address, in single/multiple instruction
. ,:1es. or in machine cycles. 1'hese modee of
: iration are discussed next. 'fhege modes can be
,.ed onlv iJ the Micromonitor is in control to start
,ircution. Execution of these commands causes the
i I:c romonitor to relinquish control.
Real Time Run (gP)
The $P key is used to start the system under test
Imling in real time. AIter the $P key is pressed two
fields are displayed as shown in Fig. iO. ft " starting
0001
BREAK
POINT
COUNTER
STARTING
ADDRESS
Fig. l6 - Real-time run display.
address field initially is blank. If no address is en-
tered, the system under test is started, after ENT is
pressed, without changing X, P, or R(P). This mode
is used to continue the microprocessor from its
present state.
If a starting address is specified, X and P are setto
0 and R(0) to the starting address. It iE important to
remember that X, P, and R(P) are not changed until
the ENT key is pressed starting the system under test.
The left field is the break point counter. After each
occurrence of a break point the count is decremented
and checked. If the result is not zeror the aystem
under tect ie automatically continued. the recult ie
that the syEtem under test stops at the nth occurrence
of a break point. The default value ie I which stops
execution at the first occlurence of a break point. See
next_section "Breakpoints" for information on setting
break points.
Between breaks, the system runs in real time as
determined by the SUTts clock. When a break is
generated, however, the SUT will require additional
time while the breakpoint counter is decremented and
checked and the log updated. See Fig. 32 in Chapter
Micromonitor Hardware under subheading
"Instruetion and Cycle Counting."
Single-Enstruction Cycle ($lt3
The single-instruction cycle mode is used to execute
a fixed number of instruetione. When the $N key is
pressed two fields are displayed as shown in Fig. lT.
0001
lNSTRUCTION
COUNTER STARTING
ADDRESS
Fig. 17 Single-lnstruction cycle display.
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16 lnstruction Manual for the RCA COSMAC Micromonitor CDP1BS030 I
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'I'he displar and operation are similar to the $P
command. The starting address is initiallv b1ank. If
no address is entered. the SLT continues tafter E\T
is pres.edl from its present state \i'ithout changing X,
P. or RtPl until the desired number of instructions
has been executed. If a starting address is specified,
X is set to t), P to 0. and Rt0t to the starting address.
ln this mode. the SUT is halted after every in-
stnrction. the instruction c{unter decremented, and
<:hecked. If the counter is not z,ero, the syatem is
rertarterl. \ote that the SUT does not operete in real
time in this mode.
Break conditions are enabled in this mode so that if
a break occurs, the SUT is halted and will not
complete the programmed set of instructions. If this
situation occurs, the break conditions are displayed
rather than the $N completion display of all zeros and
decimals. Refer to the next section "Breakpoints" for
a discussion of break conditions.
Single Machine Cycle ($S)
The single machine cycle mode is used to exeeute a
fixed number of machine cycles. To enter this mode
press the $S key. Two fields are displayed as shown in
Fig. lti. The display and operation are similar to the
MACHINE
CYCLE
COUNTER
STARTING
ADDRESS
Fig. l8 - Single machine cycle display.
$N and $P commands. With no starting address
specified, the SUT continues from it present state'
when EN'f is pressed, until the desired number
machine cycles have been executed. trf a starting
address is specified, X is set to 0, P to 0, and R(0) to
the starting address.
The SUT is stopped after each cycle and the cycle
counter decremented and checked lor zero. After the
counter reaches zero, the system stops and the
nlemory addreee and data bus ig displayed. Each
rlr.pnrxxion of the EN'[- switt:h thereafter w'ill t:utrge
(,lr(, nr()r(, ntar:hine cyt:le to occttr and the new addrtlsg
nnd rlutu btur state to be displayed. Note that no break
t:onditions are allowed in the $S mode and that all
breaks ure cleared when thie mtde is enterecl. 'Io exit
this mode, Manual Break is pressed. fhe
Micromonitor will halt SUT execution on the next S{)
cycle. It should also be noted that all commands
which do not require the Micromonitor to be in
control mar be executed in this mode. For example,
the rrser might step to a test of EFI and then set EFI
using the llicromonitor. The SS displal' of the ad-
dress and data bus may be returned by pressing $S.
Pressing ENT results in another machine cy'cle
execution if this display is present. See Chapter
"Hardware" for further information on system
operation in the $S mode.
Breakpoints
Manual Break (BK)
A Manual break can be accomplished at any time
by pressing the BK key. The display shows the
decimal point prompt, indicating that the
Micromonitor is ready to accept commands. This
facility permits, for example, breaking into a faulty
program loop which has no exit. If the location of the
loop ie unknown, the eingle-step operations ($N or
$S) can be ueed to locate the path.
A Manual break is the preferred way oI in'
terrupting a user program because the state of the
machine is preserved. The BK key will reset a WAIT
or CLEAR signal being generated by the
Micromonitor.
Break Conditions (BC)
Break conditions can be set and examined by
pressing the BC key. Each digit on the display
represents a particular break condition. The con-
ditions are printed on the case right below each digit.
A break condition enabled is shown as a 'l' and
disabled as a '0'. Initially, after the Micromonitor is
reset, no break conditions are enabled. Breaks can be
enabled on any combination of the following:
1) EFI - break when EFl goes true (EF-l : Vgg)
2l EF2 - break when EF2 goes true (El2 : V5g)
3) EF3 - break when EF3 goes true (EF3 : V5g)
4) EF4 - break when EF4 goes true (EF4 : Vgg)
5) EXT - break when the signal connected to the
EXTERNAL BREAK input is a '1' (Vpp)
6) IDL - break when an Idle occurs {3 successive Sl
statea I
?) Sl] - break when an Intermpt is acknowledged
(Sl] gtate)
lll MAS - trreak on a read/write memory condition
at a speoifietl addres'i
For MAS, the display can be one of the following:
0 - No memorY address stops
| - Break on read
1
0 0 0

l,:-:":, Keys and System Operation 17
Break on rrite
Bruak on read or write
B:'.ak conditions are set by moving the cursor to
..:,n :.,,rition of interest, entering at 1or 0, and
: ::1!r-s E\T. MAS can be set to 0, 1, 2, or 3.
\::ir E\T is pressed with the cursor under MAS,
:.-,. li=clav changes so that the address can be en-
:=:.i. as shorrn in Fig. 19. The address is modified by
::.:.:irg the number and pressingENT.
ADDRESS
FOR
MAS
Fig. 79 - Display for MASaddress entry.
Breaks normally occur synchronously at the start of
'-:. fi.r.t S0 cycle following the break condition. The
::.ak leaves R(P) pointing to the next instruction
,.:.i,:h rrould normally be executed after the break
:rdition. so that if a break is set on a branch the user
.: *e *hich path would be taken. Note that if the
=i,rroprocessor is executing an IDLE instruction
,'itn the break is taken, the next instruction is the
. i.. it,.elf .
Break Response
If the System Under Test ie stopped because of a
:::anual tBK) break or completion of a $N command,
'-11 epoffipt is displayed. If it is stopped because of the
,ripletion of a $N command, all zeroe and all
.i.,-imals are displayed. If it is stopped because of a
::.ak condition that has been set, however, the
:: i:'la)' shows the reason for the break. An example of
:.:- displav is given in Fig. 20. In this example, the
stopped with EF2 and the EXTERNAL BREAK
signal both going true.
Only those conditions which actually caused the
break are displayed. For instance, iI a break is set
only {or EFl, then the other flags will be displayed as
0's in the break response, regardless of their actual
lates lhish or l9wl.
Data Logging (LOG)
Whenever a break condition is met, or at the
completion of an instnrction in the $N mode, the
values of D, X, P, and R(P) are recorded. Up to 16
states can be preserved with the latest state displacing
the oldest in a push-down stack arrangement. To read
out the data log, push SH then LOG. 'fhe data log
number (zero being the latest state) and the values of
D and R(P) are displayed as shown in Fig. 22.
LOG D
NUMBER R (P)
X,P
Fig. 22 - Data log display showing D and R(P).
Pressing ENT increments the data log number,
stepping backwards in time. Pressing +- changes the
display to show D, X, and P as shown in Fig. 23.
0. F 8 1 0
LOG D
NUMBER
Fig. 20 - Display from set break condition
showing EF2 true.
:i liem Under Test was stopped because EF2 went
Ii t\ro or more break conditions occur
-.:ruitaneously, they are all displayed as in the
,'.."n.icle in Fig. 2l where the System Under Test was
Fig. 23 - Data log display showing D, X, and P.
Because the data log is never cleared, but only
updated, old information beyond a certain point may
notbe relevant to a particular debugging operation. It
ean only be examined when the Micromonitor is in
control.
Control of External Signa$s
Wait (WAIT)
This command can be used to set the WAIT signal
to the CPU and may be used at any time. This signal
is logically OR'd with the WAIT signal from the
SUT. Note that the display shows the Micromonitor-
generated signal, which is not necessarily the actual
state of the CPU's WAIT status. 'fo determine the
actual status, look at the LED display of the WAI'I
Iine that appears on the panel. A 'l'in the display or
the LED ON indicates that the condition is asserted
(WAIT pin of the CPU is at Vgg).
: : 27 - Display from set break conditions showing
E F2 and EXTE RNAL BR EAK true.
0. F8 0 001
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18 lnstruction Manual for the RCA COSMAC lt(icronronitor CDP1B5030
To enter the command rnode press SH then tr'AIT'
The displar it-ill be a '1' ttr--tlT assertedl or '0'
IS'AIT not asserted bv the \{icromonitorl in the
right-hand digit. Pressing E\T nill toggle the
displar .
Clear (CLR)
This command is used to set the CLEAR signal to
the CPU and may be used at any time. Like WAIT' it
is logically OR'd with the sigaal from the SUT.
Again. a 'f in the dieplayor the LED ON indicates
that CLEAR is asserted (CLEAR pin of the CPU is
at V5s).
'I'o enter the command mode press SH then
CLllAR. 'Ihe dieplay shows the Micromonitor-
generated signal (l : aaeerted, 0 : not asserted) in
ihe right-hand digit. Pressing ENT toggles the
display.
lnterrupt (lNT)
To generate an interrupt request, press SH then
INT. This signal is also OR'd with externally
generated requests. This command can be exercised
whether or not the Micromonitor is in control. The
LED on the panel indicates the status of the interrupt
request line. If ON, an interrupt request is asserted
(IIIIE-RRUPT pin of the CPU is at Vg5l.
Pressing SH, tNT resets any pending DMAIN or
DMAOUT requests from the Micromonitor. The
interrupt request is reset by any of the following (refer
to subsequent sections):
I I S3 state
2l DMAIN or DMAOUT request
3 ) Reset Request
4l Inhibit Request
Direct Memory Access
(DMAI) (DMAO)
To generate a DMAIN or DMAOUT request,
press SH then either DMA request key. These signals
are OR'd with externally generated requests' These
commands can be generated whether or not the
Micromonitor is in control. Here again, the LED's on
the panel indicate the status of the request lines (ON
for I)MA assertedl.
A DMAIN request reEets on pending Interrupt or
DMA()UT reqrreBts from the Micromonitor.
Likewise, a DMAOUT cancels Intenupt and
I)MAIN signals. The DMA requests are reset by any
of the following:
1f 52 state
2 I Interrupt request
3) Another DMA
4) Inhibit Request
5) Reset Request
Reset Request (RR)
Pressing SH and then RR reserc any pending
Interrupt or DMA requests from the Micromonitor.
This command may be exercised whether or not the
Micromonitor is in control.
lnhibit Request (lR)
Interrupt or DMA requests from the SUT can be
enabled or disabled with this command. To activate
this mode, press SH then IR. This display shows a 0
or I in the right-hand digit. A 'l' indicates that
requests are inhibited from the SUT; a '0'means that
they are enabled. The ENT srvitch toggles between
the two modes.
Note that requests from the Micromonitor are not
inhibited by this command mode. This command
may be exercised whether or not the Micromonitor is
in control.
Flag Lines (EF1) (EF2) (EF3) (EF4)
To generate a signal on a flag line, press SH
followed by the desired EF flag key. A 'f indicates
that the Micromonitor is asserting that flag line. (EF
is forced to Vg5). These signals are OR'd with signals
generated by the SUT. The Micromonitor cannot,
therefore, set a flag to '0' if the SUT is generating a
'1'. The display shows the Micromonitor-generated
signal. Check the LED on the panel for the actual
flag line status. The display is toggled by the ENT
button. These commands may be exercised whether
or not the Micromonitor is in control.
lnput Mode (lN)
The Input Mode is used to read data from the
System Under Test's input devices. To enter the
Input Mode press SH then IN. To read a device,
enier the desired device number (1'7) and press ENT.
The data received from that device is displayed. This
operation doee not alter the state of the CPU or the
SUT. Data is not altered in memory nor are any CPU
registers aflected. This command merely alkrws the
user to see w'hat will be transmitted if a particular
input instruction is issued. A sample display is given

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-: "" : -1 Tnis command can only be used
',1 : :--.:,::,:,r is in control, to the memory disable jack. This command should be
used only when the Micromonitor is in control. Refer
to the Chapter on Hardware for more information on
adding external memory.
Terminal Option (10) (90) (120)
The Micromonitor alwaye starts with the built-in
keyboard in control after it is Reset. Control san be
transferred to an external terminal by pressing StrI
followed by the key selecting the desired baud rate
(10, 30, or 120 characters per second). A decimal
point prompt is then typed. Control is returned to the
keyboard when a $K is typed on rhe terminal. The
decimal -point prompt will again be displayed. Refer
to the Chapter on Hardware for a discussion of
!g.pT{ interfacing. Control can be transferred only
if the Micromonitor is in control.
A eummary of all keyboard commantls is given in
Appendix A.
Parameter Pass Feature
A built-in feature of Micromonitor operation
perrnits examination of X, R(X) and MR(X); or p,
R(P) and MR(P); or any MR(N) with only three
(four for X) key strokes. When the Memory mode is
entered, the initial address is 0000 unless the register
mode has been accessed since the last memory mode
selection. In that case the address will come from the
register last selected. For example, to show the
contents of MR(3), do the following:
if the
]EVICE
[. IJ\IBER DATA
BYTE
: .- 2! - 9mple input mode display showing
devlce number and data byte.
Output Mode (OUT)
i,a= ran be sent to a specilied output device using
'-.- i I '::!,ut \[ode. This mode is entered by pressing
-:i ::.n OLT. The display has three data fields as
.- ,': in Fig. 25, the data byte, the output device
:. -:.irr. and the memorv address.
DATA DEVICE MEMORY
BYTE NUMBER ADDRESS
" ; 25 - Three data fields for output mode display.
i:iriailr'. the iddress and device number fields are
:-: . The data lield initially shows the contenm of the
-*.=,-'ted address. Move the cursor and enter values, as
:. :-.i Lred. f or the data byte to be output, for the device
:.-.:.-rber of the output port (N:1-7), and for the
::rr,'r'\. address from which the data is to be sent.
i:..sins ENT causes the output operation to occur.
II no data is specified, the byte already at that
:,.morv location is sent. If data is specified, the
:.:rnor\ address must, of course, be a RAM location.
-" brte already there is saved by the Micromonitor
.:: l restored after the output operation, thus leaving
:-:, CPL and system memory unaffected by the
:.:ation. This cornmand can only be used if the
lr[. r,-rmonitor is in control,
Control of External Options
External Memory (EXM)
Erternal Memory can be substituted for the
:i:morv of the SUT with this command. To enter this
:.. ,de. press SH then EXM. The display shows a'In
: r.r'. A '1'deselects the memory of the SUT and
-.tcts the memory in the extemal memory socket.
f he E\T button toggles the value of the display. Do
:,,r .et EXM to I unless the SUT memory is
i,.elected either by removal or by proper connection
Press Key
R
3
M
Display
0180 0.
41V2 3
4.1.7.2. 21
R3 MR(3)
Similarly, when the Regiater mode is entered, the
initial register number is 0 unless the X-P mode was
accessed since the last register mode selection. In that
case, the register number will be thi value in X or p
depending on the position of the cursor when the X-P
mode was left. For example, to examine MR(p), do
the following (P:5):
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