RCA CDP18S711 manual COSMAC VIP Operation, Using the Operating System, Memory Write

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11.COSMAC VIP Operation

COSMAC VIP is operated with the RUN switch and hex keyboard. The PWR light shows that power is on. The Q light is activated by various programs. A tone is sounded whenever the Q light is on. The TAPE light glows when cassette input data is present. When using COSMAC VIP, always start with the RUN switch in the down (or reset) position. Flipping the RUN switch up initiates execution of machine language programs beginning at memory location 0000. If you have previously stored the CHIP-8 Ian_ guage interpreter program at locations 0000-01FF, execution of a program written in this language will begin at 0200. To manually terminate execution of any program, flip RUN down.

Using the Operating System

With COSMAC VIP you can load programs into memory from the hex keyboard or cassette recorder, record the contents of memory on cassettes, show the contents of memory bytes in hex form on the display, and examine the contents of CDP1802 microprocessor registers. These functions are performed with the aid of a special program called an operating system. This operating system is contained in a ROM so that it's ready to use as soon as power is turned on. It is located at memory locations 8000-81FF. A machine code listing and summary of this operating system is provided in Appendix B.

To use the operating system hold key C down on the hex keyboard when you flip RUN up. You will hear a tone. Release key C and you're ready to use the operating system.

After selecting the operating system you can do four different operations as shown in the following table:

KEY

OPERATION

0

MW (Memory Write)

A

MR (Memory Read)

F

TW (Tape Write) TR

B

(Tape Read)

For any of these operations you must first enter a memory address. Enter the 4 hex digits of any memory address using the hex keyboard (most significant digit first). You will see the address at the lower left of the screen and the byte contained in that address at the lower right. Remember that addresses and bytes are always entered and shown in hex form. Suppose you entered 0200. You will see 0200 at the bottom left of the screen and the byte stored at 0200 at the lower right.

Memory Write

If you want to change this byte, press the 0 key. Now press two digits of the new byte (most significant digit first) and it will be stored at 0200 replacing the original byte. You will see this change on the screen. If you enter another byte it will be shown and stored at the next higher address in sequence (0201 in this example). You can load any, sequence of bytes directly from the hex keyboard in this manner. If you make a mistake, flip RUN down. With key C pressed, flip RUN back up. Enter the address at which you made the error. Press key 0 and resume entering your program.

Note the random bit pattern on the screen above the hex display. This pattern is the binary data

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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 What You See Turning It On1. Getting Started Using the Operating System 11.COSMAC VIP OperationMemory Write Memory Read Tape WriteTape Read 11.COSMAC VIP Operation Testing Your Cassette SystemHow to Change and Use the Variables III.CHIP-8Language ProgrammingBranch 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 V. Logic Description How Memory Is AddressedHow 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/OutputUsing the Expansion Interface Some Expansion IdeasI RCA COSMAC VIP Instruction Manual Pin Signal V1. Expansion Considerations and ConnectionsTable III - External Option Terminal Connections 2.Composing poetry or pictures with printer output Other Problems VIL Troubleshooting HintsSignal Tracing No SoundLast Resorts Appendix A - Test and Operating Data Byte Pattern for Displaying COSMACBeeper Program Cassette Attachment Diagram Cassette Phase Test SignalsTest Program Cassette Data Test Memory Test Program Cassette Recording GuidelinesOperating System Listing Appendix B - Operating SystemOperating System Register Table Operating System SummaryR3 = Machine Language Subroutine Program Counter CHIP-8Interpreter Listing Appendix C - CHIP-8InterpreterCHIP-8Memory Map CDP1802 Register Use for CHIP-8Interpreter 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