RCA CDP18S711 manual Using the Display Instructions

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RCA COSMAC VIP Instruction Manual

 

Table I - CHIP-8 Instructions

Instruction

Operation

1MMM

Go to 0MMM

BMMM

Go to 0MMM + V0

2MMM

Do subroutine at 0MMM (must end with 00EE)

00EE

Return from subroutine

3XKK

Skip next instruction if VX = KK

4XKK

Skip next instruction if VX n.e. KK

5XY0

Skip next instruction if VX = VY

9XY0

Skip next instruction if VX n.e. VY

EX9E

Skip next instruction if VX = Hex key (LSD)

EXAl

Skip next instruction if VX n.e. Hex key (LSD)

6XKK

Let VX = KK

CXKK

Let VX = Random Byte (KK = Mask)

7XKK

Let VX=VX+ KK

8XY0

Let VX = VY

8XY1

Let VX = VX/VY (VF changed)

8XY2

Let VX = VX & VY (VF changed)

8XY4

Let VX=VX +VY(VF=00 if VX+VY l.e. FF,VF=01 if VX +VY>FF)

8XY5

Let VX = VX - VY (VF = 00 if VX < VY, VF = 01 if VX g.e. VY)

FX07

Let VX = current timer value

FX0A

Let VX = hex key digit (waits for any key pressed)

FX15

Set timer = VX (01 = 1/60 second)

FX18

Set tone duration = VX (01 = 1/60 second)

AMMM

Let I = 0MMM

FX1E

Let I = I + VX

FX29

Let I = 5-byte display pattern for LSD of VX

FX33

Let MI = 3-decimal digit equivalent of VX (I unchanged)

FX55

Let MI = V0:VX (I = I + X + 1)

FX65

Let V0: VX MI (I = I + X + 1)

00E0

Erase display (all 0's)

DXYN

Show n-byte MI pattern at VX-VY coordinates.

 

I unchanged. MI pattern is combined with existing display via EXCLUSIVE-OR function.

 

VF = 01 if a 1 in MI pattern matches 1 in existing display.

0MMM

Do machine language subroutine at 0MMM (subroutine must end with D4 byte)

three RAM bytes addressed by I contain the decimal equivalent of the value of V9.

If 1 =0327, a F355 instruction will cause the values of VO, V1, V2, and V3 to be stored at memory locations 0327, 0328, 0329, and 032A. If 1=0410, a F265 instruction would set V0, V1, and V2 to the values of the bytes stored at RAM locations 0410, 0411, and 0412. FX55 and FX65 let you store the values of variables in RAM and set the values of variables to RAM bytes. A sequence of variables (V0 to VX) is always transferred to or from RAM. If X = 0, only VO is transferred.

The 8XYI, 8XY2, and 8XY4, and 8XY5 instructions perform logic and binary arithmetic operations on two 1-byte variables. VF is used for overflow in the arithmetic operations.

Using the Display

Instructions

An 00E0 instruction erases the screen to all 0's. When the CHIP-8 language is used, 256 bytes of RAM are displayed on the screen as'an array of spots 64 wide by 32 high. A white spot represents a I bit in RAM, while a dark (or off) spot represents a 0 bit in RAM. Each spot position on th ' e screen can be located by a pair of coordinates as shown in Fig. 1.

The VX byte value specifies the number of horizontal spot positions from the upper left corner of the display. The VY byte value specifies the number of vertical spot positions from the upper left corner of the display.

The DXYN instruction is used to show a pattern of spots on the screen. Suppose we wanted to form the

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Contents Page VIP-311 RCA COSMAC VIP CDP18S711 Instruction ManualACKNOWLEDGMENT Contents Contents Continued What This Manual Covers 1. Getting StartedThe Power Supply Turning It On What You See1. Getting Started 11.COSMAC VIP Operation Using the Operating SystemMemory Write Tape Write Memory ReadTape Read 11.COSMAC VIP Operation Testing Your Cassette SystemIII.CHIP-8Language Programming How to Change and Use the VariablesBranch Instructions Using the Display Instructions 0200 A20A I=020A 0202 6100 V1=00 0204 6200 V2=00 III. CHIP-8 Language Programming0206 D125 SHOW 5MI@VlV2 0208 1208 GO 020A F090 020C F090 020E F000Applying CHIP-8 111. CHIP-8Language Programming Some Program Ideas25.PROGRAMMED SPOT - Introduce children to programming concepts by letting them preprogram the movements of a spot or object on the screen VIP Machine Coding IV. Machine Language ProgrammingMachine Language Programming Summed Up How Memory Is Addressed V. Logic DescriptionHow the Input/Output Works pressed. A 62 machine instruction causes the least significant 4 bits of memory byte to be latched into U13. These 4 bits are decoded to bring one of the 16 U13 output lines low. If the key that corresponds to this output line is pressed, the CDPI802 EF3 input will go low. The 4-bitcodes latched into U13 correspond to the equivalent key positions. After the program send8 a 4-bitcode to U13, it subsequently examines the EF3 line to see if the key corresponding to this code is pressed or not. In this manner, a program can determine when any specific key is pressed or can sequentially scan all keys while waiting for any one to be pressed. Key debounce delays must be provided in the program when required. A program can also cause a speaker tone to occur when a key is pressed. Only one key at a time should be pressed with this method of interfacing the keyboard V1. Expansion Considerations and Connections Using the Byte Input/OutputSome Expansion Ideas Using the Expansion InterfaceI RCA COSMAC VIP Instruction Manual V1. Expansion Considerations and Connections Pin SignalTable III - External Option Terminal Connections 2.Composing poetry or pictures with printer output Other Problems VIL Troubleshooting HintsSignal Tracing No SoundLast Resorts Byte Pattern for Displaying COSMAC Appendix A - Test and Operating DataBeeper Program Signals Cassette Attachment Diagram Cassette Phase TestTest Program Cassette Data Test Memory Test Program Cassette Recording GuidelinesOperating System Listing Appendix B - Operating SystemOperating System Summary Operating System Register TableR3 = Machine Language Subroutine Program Counter CHIP-8Interpreter Listing Appendix C - CHIP-8InterpreterCDP1802 Register Use for CHIP-8 CHIP-8Memory MapInterpreter Appendix C - CHIP-8Interpreter RCA COSMAC VIP Instruction Manual CHIP-8User NotesPage 1. VIP Kaleidoscope 2. VIP Video Display Drawing Game Fig. E-5Power Supply Circuit and Byte Appendix E - Logic DiagramsFig. E-1Microprocessor and Display Interface CircuitsPage Appendix E - Logic Diagrams Fig. E-2- ROM Circuits and Expansion InterfacePage Appendix E - Logic Diagrams Fig. E-4- RAM CircuitsRCA COSMAC VIP Instruction Manuel RCA COSMAC VIP Instruction Manual Appendix F Board Layout, Parts List, and Expansion Notes2.Parts List for RCA COSMAC VIP CDP18S711 1.Printed Circuit Board LayoutRCA COSMAC VIP Instruction Manual Page 2. Parts List for RCA COSMAC VIP CDP18S711 Page Resistors - Supplied 1 /4 W except as noted RCA COSMAC VIP Instruction ManualPage 3. COSMAC VIP Expansion Notes
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