Ulrich Rohde, N1UL, recognized for pioneering work on SDR

While working under a U.S. Department of Defense contract at RCA in 1982, Rohde's department developed the first Software Defined Radio, which used the COSMAC (Complementary Symmetry Monolithic Array Computer) chip. Introduced by RCA in early 1976, the RCA CDP1802 eight-bit CMOS microprocessor - a 40-pin LSI integrated circuit chip - was the company's first single-chip microprocessor. Rohde was among the first to present publicly on this topic with his February 1984 talk, "Digital HF Radio: A Sampling of Techniques" at the Third International Conference on HF Communication Systems and Techniques in London.

RCA Solid State Europe entered the microprocessor market early in 1975 with the announcement of COSMAC, initially conceived as a two-chip general-purpose computing element aimed at inexpensive digital systems. The 8-bit microprocessor architecture is designed to give great flexibility, simplicity of programming and inexpensive interfacing, while the instruction set and input/output interface are designed to minimize memory requirements and system complexity. The microprocessor uses complementary MOS technology, characterized by very low power consumption, high noise immunity and tolerance to supply-voltage variations.

In November 1975, RCA announced the full commercial availability of a microprocessor family, encompassing the existing COSMAC (then designated CDP1801, but now replaced by the single-chip CDP1802).

A recent development from RCA Solid State, the CDP1802 is a logical extension of the earlier products. Essentially using the same architecture as the initial COSMAC device, it is a single-chip microprocessor using self-aligned silicon-gate C-MOS technology. The CDP1802 is accompanied by a series of peripheral and interface circuits, including ROMs and RAMs using silicon-gate and silicon-on-sapphire technology, plus input and output circuits.

The main features of the CDP1802 architecture are: simple architecture for ease of understanding by the user; the concept of separating addresses from instructions placing them instead into an array of internal registers and thus allowing many compact one-byte instructions; powerful built-in interface capabilities.

Microprocessors are available in different technologies -- PMOS, NMOS, bipolar, and CMOS. CMOS has the distinct advantages of low power dissipation and wide-temperature operation. RCA's 1801 microprocessor was a two-unit deal that was relatively slow and expensive. Started out at $200, the price of the pair dropped into the still unattractive $50 range.

But they haven't been sleeping! Just announced is a single-package CDP1802 COSMAC microprocessor that is a dramatic improvement over the earlier version. New instruction repertoire has been added, cost is competitive, down to under $30 levels, and the execution speed of single-cycle instructions is down to 2.5 microseconds. Standard aluminum gate construction has been supplanted with a self-aligned silicon-gate process that cuts down chip area and increases yield.

RCA's new 230 x 180-mil μP retains the unique architecture of the older 1801 design. Programs written for the earlier circuit will run without change on the new one. It is built with a new C²L closed-COS/MOS logic. Source connections are common and separate contacts are not needed. Guardbands to prevent parasitic action are not needed, yet the CDP1802D can operate at full supply range of 3-12 volts.

The CDP1802 block diagram in Fig. 2 shows an 8-bit address bus MA0 through MA7. The bus is time-multiplexed to 16 bits. Storing the first 8 bits in an external latch gives 65K of memory addressing capability. Sixteen general-purpose registers distinguish the RCA approach from contemporary processors. Each register is 16 bits long, which adds up to 32 8-bit bytes or a total of 256 read-write scratchpad bits. By loading these registers with frequently used addresses and data, efficient programming code can he written. Single-byte instructions replace multiple-byte main memory addressing operations in other schemes.

Any register can he designated as the program counter or data pointer. One of three 4-bit registers selects the particular one of the 2⁴ scratchpad registers.

Many of the memory and register instructions include a 4-hit operand that is stored in the N register. The most significant 4 bits of the instruction is the operation code and is stored in the 4 bit I register. For example, the instruction format IN is an increment register operation. To increment register 5 by one, the instructions would be 15 in hex or 00010101 in binary. Binary number 0001 would he stored in the I register and 0101 in the N register. The control logic decodes the op-code and sends out signals to direct the N register to select register 5 in the array. The control logic then causes the addressed register to he incremented by one by the incr decr block in Fig. 2.

In instructions where register addressing is not used, all 8 bits are interpreted by the control logic and none of the scratchpad registers are selected.

The 4-bit P register decides which of the 16 is to be used as the program counter. The program counter holds the address of the program stored in memory and is incremented sequentially to fetch successive program steps.

The 4-bit X register picks the register to be referenced by arithmetic and logic operations.

Interruptions in program executions by peripherals such as terminals and disk memories are standard computer procedures. The 8-bit T register is used to hold the X and P register contents and store them in a single memory-location. After servicing the inter- rupting device with a special program routine, the T register is used to reset X and P to their original values so the main program can continue from where it left off.

The 8-bit D register is the μP accumulator. Data is transferred in either direction between the D and scratchpad registers. Since the general registers are twice the length of the D register, either the low or high byte can he loaded by separate instructions.

Data transferred to and from memory must pass through the accumulator and is handled by a series of eight memory reference instructions. The instructions use either the X or P registers as operands. These pointers will either stay fixed or will be automatically incremented by the choice of instruction.

Arithmetic and logic operations take place between memory and the D accumulator, governed by an extensive series of instructions. The 1802 has a number of new immediate instructions that are two bytes in length. These load constants or use them as other operands. Immediate means the constant is stored in the second byte of the instruction. This is very useful when setting up indexes or initial memory pointers, which can then be incremented or decremented by the program.

At the heart of many machine-language routines are the branch instructions, and a large assortment will save programming code. The 1802 selection includes two-byte short branches where the second byte is the address that replaces the low program counter byte. Jumps over a 2⁸, 256 word total range on the same memory page use these instructions. New to the 1802 are long branches that are three-bytes and allow jumps to any location in memory. The high and low address bytes to be inserted into the program counter are in the second and third instruction words. Except for the unconditional branches, the decision to jump or not is based on the state of the D register, and the DF, Q, and EF flags. DF, the data flag, is a one-bit ALU carry flip-flop. Q is a program controlled flag, and EF1 through EF4 are a group of flags controlled by peripherals.

Short and long skip instructions are similar to the branches in that they are executed in response to the same flag conditions, but their action is limited to the skipping of either one or two steps in the program. They are single-byte instructions that are very efficient in terms of memory space.

The ten control instructions include the stack return and idle operations. The remaining group are the output instructions that route data from the registers pointed to by X to the output data bus or from the input data bus. During input-output operations, the 4-bit N register is set to a value between 1 and 7 and used to select the peripheral device.

The unit price of the 4-6-volt 5-μs CDP1802D is $29.50. The 3-12 volt full speed CDP1802CD is $43.50. Information is available from RCA Solid State Division, Route 202, Somerville, NJ 08876.

Infinite, Inc., takes two different approaches to the microcomputer learning/development system. First, they produce a training-and-use package that leads the uninitiated unfalteringly into the world of the computer. For example, their model UCI800 microcomputer is a completely assembled and self-contained microcomputer system. It avoids construction pitfalls and the futile troubleshooting that often follows. To determine whether a problem is in the microprocessor IC or elsewhere can be very difficult without the necessary skill and sophisticated equipment.

On the other hand, Infinite has also developed the model UC1800HK Hobbyist Kit for the experienced kit builder. The kit contains only special components that are not widely available.

The UC1800 is a completely assembled microcomputer system built around the RCA COSMAC model CDP1802 microprocessor. Four printed-circuit boards are mounted in a console-type cabinet that resembles a desk-type calculator.

The central processor board holds the CPU IC, the CPU control logic, 256 words of NMOS RAM and the 5-volt power supply (except the power transformer mounted separately in the cabinet). The CPU board has a 72-pin gold-plated edge connector for system expansion. The readout board has four 7-segment LED displays and the associated decoder-driver IC's. Two displays function as the address readout, and the other two as the instruction and input/output readouts. The LED's display the hexadecimal (base 16) representation of the computer's binary numbers. After 0 through 9, A, C, E and F are displayed and "b" and "d", using the available segments. The board contains its own 5-volt regulator IC to supply the substantial 400-mA current drain.

The third board is the switch-control module that interfaces with the six control switches. They are RESET, SINGLE STEP, START/EFI, POWER, MODE and SINGLE STEP/ENTER.

The board has outputs that connect to the EF1, CLR, WAIT, and DMA IN, terminals on the microprocessor IC.

The keyboard module holds the 16 hexadecimal keys and the necessary debouncing and decoding components. Two LED's indicate whether the most or least significant of the two hex digits in each word is ready for loading.

To load a program, set the MODE switch to LOAD, then RESET, enter the first word, press ENTER and continue. The loading starts at 00 and proceeds sequentially. If you make a mistake along the way, you must either start all over or enter a short program that allows you to change a particular memory location.

After the program is loaded, the MODE switch is then placed in the RUN position and the SINGLE STEP switch can be turned either ON or OFF. With the switch OFF, the computer executes the program automatically. With the switch ON, the computer executes a single instruction for each push of the SINGLE STEP/ENTER button. The START switch shares the EFI input function that you can use to interact with your program. Input and output instructions permit you to enter data from the keyboard and readout into the two LED's.

The POWER switch maintains power to the memory only in the STANDBY position to preserve the program with minimum power consumption. You can also purchase a nickel-cadmium battery and charger to keep the memory alive for about four hours after loss of primary AC power.

The DMA (Direct Memory Access) design of the model CDP1802 facilitates program loading without using a ROM utility program. There is an advantage in not requiring this extra component, but it does make the system cumbersome to use.

Infinite addresses this problem by including a listing and instruction for using KEYBUG as part of the UCI800 package. This program takes one-half of the available 256 memory words, and of course it must be successfully loaded starting at address 00.

KEYBUG has five commands that help in loading, examining and changing memory contents. After the program is loaded, a RESET-START sequence gives control to KEYBUG, which is acknowledged by displaying "db" (debug).

The DC command will display the contents of a single memory location. Press the D and the C followed by EF1, which serves to enter the command. Then key in the address of the location to be displayed and press EF1 again. The program responds by displaying the memory contents. The CC command changes the contents of memory. After the command and the memory-location address are entered, the new contents are keyed in and EF1 depressed. Since only a single memory location is accessed by the DC and CC commands, the system can return to KEYBUG automatically and be ready for a new command.

To examine a series of memory locations without entering memory addresses sequentially use the FD (forward display) command. The computer displays the address and its contents; then increments the address and displays its contents each time EF1 is pressed. Similarly, the FC forward change command sequentially loads the memory by pressing the EF1 switch after each data entry. These last two commands are self-looping; the only way to exit the loop so that a new command can be executed is to reset and restart KEYBUG.

The remaining command is EE for execute. The EE command is keyed in, EF1 pressed, the program-starting address entered and EF1 pushed again. Because KEYBUG starts at 00 and a program cannot be written there, EE is the only way to activate a program.

To debug your program, set breakpoints by inserting a branch to 00; this causes a "db" readout when KEYBUG is reached. You can then examine memory to see what has taken place so far. A more sophisticated approach would be to examine the processor registers when the breakpoint is reached, restarting the program and continuing to the next breakpoint.

So far KEYBUG is not available on PROM or ROM and must be loaded manually into RAM. A defective user program may destroy the utility program. This happened several times while I was experimenting with some simple programs. Some wipeouts did not completely annihilate the system, and it was possible to use KEYBUG to find the destroyed memory locations and restore the full capabili- ties. Some wipeouts were total.

The Infinite computer is available in four versions: The completely assembled and documented UC1800 package includes computer, instruction manual, RCA MPM-201A CDP1802 Users Manual, KEYBUG program and Cardiac. Cardiac (Cardboard Illustrative Aid to Com- putation) was developed by Bell Telephone Laboratories to simulate the operation of a simple computer. Cardboard slides simulate the instruction decoding, and calculation is done with pencil and paper. The package is priced at $495, plus $8 for shipping and handling. Option 001 is the battery backup and recharger and sells for $22.50. Option 002 enables you to use the microcomputer with either 120 or 230 VAC 50-500-Hz input power and costs $15.

The UC1800 kit includes everything but the cabinet and power cord. The four modules are factory-assembled and burned-in. This version sells for $389, plus $4 for shipping and handling.

The economy model (model UC1800HK) contains four unwired boards, keyboard, 1802 CPU, readouts, cable and Users Manual. It is priced at $129.95, plus $2 for shipping and handling. If you already have a CDP 1802, Option 003 subtracts $18 from the price.

The RCA Video Interface Processor is a hobbyist microcomputer with a graphic video output. As soon as it is assembled and operational, you become acquainted with the system by loading and running an assortment of video games, including "Kaleidoscope" and (my favorite) "Armored Vehicle Clash." After you gain this initial familiarity and have some fun, you can graduate to writing 1802 machine language and CHIP-8 programs.

The VIP is constructed on a single 8 1/2 X 11-inch PC board that holds the CDP1802 microprocessor, 2048 words of user RAM, a 512-word ROM-based operating system, a 3.521280-MHz crystal oscillator, a video display generator IC, a cassette recorder interface and various system related IC's. A 5-volt, 600-mA power-supply module is part of the package. On-board memory can be increased to 4096 words (a higher current supply may be needed), and parallel I/O ports can be added by filling wired, empty IC positions. Standard 44-pin connectors can be used to expand up to 32,000 memory bytes, and beyond the 19-line on-board I/O limitation.

Programs, data and system control commands are entered through a 16-key hexadecimal keypad. Depressing a key switch on the keyboard operates the Q light, affects the on-screen display and generates an audio tone (the speaker is not included). The uppermost 256-byte portion of memory is displayed in a format that is 64 bits horizontal by 32 bits vertical. The video output is monochrome and noninterlaced, and must be connected to a video monitor, the video circuits of a TV receiver, or an external RF modulator for hookup to a TV antenna terminals. User programs are started at address 0000 by flipping the reset toggle switch from RES to RUN. To access the 512-word operating system at address 8000, key C is held while the reset switch is flipped.

The operating system has four functions - memory write, memory read, tape write and tape read. When memory contents are entered and checked, the address and contents are displayed simultaneously at the bottom of the TV screen, so you can keep track of what you are doing. The video format can be expanded to 64 X 64 bits or 64 X 128 bits for higher resolution by writing your own video refresh interrupt routine in machine language. Video format expansion uses more memory for the display (512 bytes or 1024 bytes). Using the video display slows down the processor because of the time it spends translating memory contents into a video display pattern. The operating system saves the processor registers on the last page of memory for debugging programs.

The CHIP-8 interpreter is a 5I2-byte program that you must load manually, or from tape, into locations 0-01FF. CHIP-8 user programs, such as games, are then loaded starting at 0200. The language is a series of 31 two-byte instructions that let you control up to 15 variables, run a timer, display patterns, generate a variable-duration audio-output tone, convert binary to decimal, obtain random numbers and perform skips and subroutine jumps. You can create all kinds of static and moving displays with relatively few instructions. The CHIP-8 interpreter should be stored on cassette tape to save reloading and checking each time you want to use it.

A VIP operating manual, the MPM-201 1802 microprocessor manual, and data sheets describing the ROM, video display IC and 1802 microprocessor are included. The VIP manual includes all the details, but a beginning computer hobbyist will find a reference book or two helpful. Twenty video games are listed, plus some short "getting-started" programs.

Kit assembly requires good soldering technique since a single short between the necessarily close PC traces keeps the unit from creating its pretty pictures. While the VIP is basically designed to be used for fun, it can be expanded to perform useful control and calculation work.

After I resolved a couple of self-inflicted assembly errors, the system performed flawlessly. Programing mistakes did have the annoying habit of wiping out CHIP-8, but shifting to the tape cassette mode of operation made recovery easy. I used both an inexpensive time-worn audio cassette recorder and a better-grade Heathkit tape deck. The tape deck loaded programs successively nine times out of 10, but the less expensive recorder performed only once out of every three times.

The model CDPI8S022 VIP Kit is priced at $275. An order form is available from RCA Solid State Division, Box 3200, Somerville, NJ 08876.

The RCA 1800 series COSMAC microprocessor and its associated family of devices have a couple of unique characteristics. First, because they are COS/MOS devices, the power drain is low, starting at the milliwatt level. Single-IC standby memory power is also in the low milliwatt range.

Second, the 1800 family tolerates an unusually wide power supply range - 3 to 12 volts for the CDP1802 with a 3.2-MHz clock. And the operating temperature range for the full-speed processor and certain memory products covers the full -55 to 125°C temperature range. This is important if your microprocessor-controlled gadget will form part of an automotive system.

The processor instruction set is based on a 16- X 16-bit scratch-pad organization that provides good programming flexibility.

The RCA CDP18S020 Evaluation Kit is a relatively inexpensive tool with which to learn about the RCA 1802, prototype a microcomputer system, or develop software. A 20-mA loop or RS232C terminal is normally required to use the Evaluation Kit, although a simple keyboard or switch interface can be designed. Board dimensions are 14 X 9.7 inches, including fully decoded prewired locations for expansion to 4096 bytes of random-access memory (RAM), and a 6- X 4-inch user area wired to accept standard DIP packages.

Three edge connectors provide access to the microprocessor pins and the user input-output (I /O) area, and connect to external power sources and peripheral devices. The kit comes with a 2-MHz crystal which, for the 16- and 24-clock-period instructions, calculates to 8-µs or 12-µs execution times. A 6.4-MHz oscillator reduces these values to 2.5 and 3.75 µs.

A 512-byte ROM is assigned address space from 8000 to 81FF and permanently stores the UT4 monitor program. A 32-word RAM starting at 8C00 is used by the utility program to store register contents. Two supplied RAM IC's fit into the first two locations in the 4K memory area for an initial 256-word user programming space.

System operation is controlled by three pushbuttons and a toggle switch. The RESET pushbutton intializes the CPU and control logic: RUN U (Run Utility) gives control to the ROM monitor program by starting execution at 8000. The RUN P (Run Program) pushbutton starts program execution at 0000, where the first user's program instruction is usually entered. The CONTINUOUS/STEP toggle switch lets the user choose between the normal clocked mode or single-cycle operation, where individual program steps can be dissected down to 2 machine or 3 machine cycles-per-instruction.

A series of 29 LED's display the status of the 16-bit memory address bus, the 8-bit data bus, the SO and SI processor state codes, the CLEAR and WAIT control signals, and the processor's Q flip-flop. Bidirectional communications to a data terminal are provided by interface circuits that use the Q flip-flop for output and the EF4 flag to input the serial data. Detailed instructions show how to hook up to current loop terminals such as Teletypes, and to EIA RS232C interfaces such as Texas Instruments' Silent 700 terminal. Parallel 8 -bit input and output ports are included in the kit.

External power supplies are required - of 5 volts at 600 mA, or 10 volts at 200 mA with a separate 5-volt 400-mA supply for the LED's.

Assembly
Kit assembly was pleasantly uneventful with the help of a high-quality, double-sided PC board with plated-through holes. Close PC runs are necessity on microcomputer boards, and careful soldering and inspection techniques are a must. Sockets are provided for the microprocessor and utility ROM IC's, but, as always, I recommend using additional sockets or Molex pins to mount some or all of the remaining 22 circuits.

The checkout procedures consists of measuring the resistance of the supply input leads, and loading and executing a four-instruction program that sets and resets flip-flop Q.

Figure 1 demonstrates the writing of data to memory, the reading of data from memory, and starting programs. The UT4 program recognizes three commands corresponding to each of these functions.

After pressing the RESET and RUN U push-buttons, type either a carriage return or a line feed depending on whether your terminal is connected for full-duplex or half-duplex operation. Full-duplex operation requires the computer to echo back characters typed on the keyboard to the printer, since the two terminal functions are completely isolated. Based on the first character typed, the utility program sets up to echo or not, and calculates the bit timing necessary to talk and listen to the terminal.

Figure 1 shows how the three-command repertoire works. First, you enter a program either from the keyboard or from punched paper or magnetic tape. The command !M is the write-memory command, which is immediately followed by the address where the input should be entered - in this case, 0 or 0000. The space after the 0 separates the address from the data. Next, the program instructions or data are entered in hexadecimal format, with each two characters accounting for a single memory word. In hexadecimal or base 16 format, additional symbols are needed for numbers between 10 to 15. Letters from A through F are used to represent 10 through 15 with a single symbol.

Spaces can be imbedded between words if desired. At the end of the line, you have a number of choices. In Fig. 1 the first line is terminated by a semicolon. This told the machine I wasn't finished yet, and that I will give a new address and more input. Everything else was ignored until the next hexadecimal digit. I then added an extra line feed to make the printout more legible. On the second line I started to type 10 but decided I really wanted to enter more data starting at address 20. The system (being forgiving) only pays attention to the last four numbers entered, so I typed 0020 (or I could have typed 020 since one 0 was already there from the 10). I then hit the space bar and typed in the data.

This time I hit a comma at the end of the line that told the machine I still had more data to enter but wanted to continue on the next line. With the comma the data continues in sequence and a new address is not given. At the end of the third line I decided to go back and fill in data starting at 000F; so I used the semicolon again.

Finally, at the end of line 4, I simply used a carriage return, indicating I was through, and the machine responded with the prompt asterisk on the following line.

At this point, you're ready to check by reading out memory contents with the ?M command. Again, you use 0 as the starting address; however, the 30 is not data but the number of words in hexadecimal format to be typed out - 3016 = 3 X 16 = 4810 words. The next three lines represent the response to that command. The first four columns display the starting address for each line followed by 16 words grouped by two's. The last byte on the 0000 line is the AF that I inserted at address 000F on line 4.

Note the format that the machine uses to output memory contents. The first two lines begin with addresses and end with semicolons, and the third line starts with an address (0020) and ends with a carriage return. This allows the data to be stored on tape in this format and then later be read back in using the compatible !M command.

The next group of lines demonstrate a memory dump of 10₁₆ or 16₁₀ words starting at 0020.

The UT4 monitor program uses a 32-byte RAM starting at 8C00 to store the 16 scratch-pad microprocessor registers. This feature is helpful in troubleshooting, but care must be used since certain registers are modified by the system. The program cannot be restarted from an intermediate point after being interrupted by inserting an idle instruction unless the registers are restored.

The next three lines in Fig. 1 show how the register RAM is printed out with the ?M8C00 20 command. Characters RO and R7 are displayed on the line prefixed by 8C00, and R8 through RF on the line starting with 8C10.

Command $P starts program execution. If no address is given, execution begins wherever the program counter is set, usually at 0000. Otherwise, the program is started at the address typed immediately after $P.

A large loose-leaf binder comes with the kit. It includes detailed sections on kit assembly, design and operation of the system, the utility program (including listing), application notes on I/O and control, software and memory.

The CDP18S20 evaluation Kit is priced at $249 and is available from RCA Solid State Division, Somerville, NJ 08876, or from RCA Solid State distributors.

The CDS II development system for CDP1802 microprocessors includes a 19in rack-mountable chassis with printed-circuit backplane, internal power supplies, clock and controls, a front panel with controls and display, and seven plug-in printed-circuit modules including a central processor, control, address-latch and bank-select, RAM and ROM memories, I/O decode, and terminal interface. Seven spare memory module positions and ten spare I/O positions are provided. Extra memory or I/O modules are available as options.

The CDS II comes with both papertape and magnetic-tape cassette versions of the resident editor and assembler programs which can be loaded into the 4 kbytes RAM supplied. A floppy disc option is also available. The utility program provided allows the user to inspect and modify memory and to start program execution at any location. It can also load programs, dump memory, and interface terminals for serial ASCII data terminals. It automatically adjusts to baud rates between 110 and 1200 operates in full or half duplex mode (RCA Solid State Limited, Sunbury-on-Thames, Middx, UK. Telephone Sunbury-on-Thames 85511).

RCA's 1802 8-bit CMOS microprocessor is to be supported by the Tektronix 8001/8002A microprocessor development lab. Because of its CMOS characteristics, the 1802 is widely used in severe environments and/or portable applications.

A resident utility program for RCA's 1802 microprocessor has been developed by the Golden River Company. The program, GRUTIL, will provide 1802 users with the capability to load a program from an external source such as a Teletype keyboard, paper tape or a timesharing system. The program runs directly on Golden River's GR0430 low power SBC and on the MK4 control system.

By using one of four specified commands the user may interrogate memory and punch a reloadable paper tape, enter data into memory or load a program, transfer blocks of memory from one location to another or proceed with program execution. GRUTIL will detect bad syntax and data errors and allow the aborting of wrong commands. The output may be terminated at any time by the user.

The program is available in ROM or PROM and can be contained in a 1k chip. Program size is less than 1024 bytes of CDP 1802 machine code. Input may be either Teletype and paper tape or magnetic tape and cassettes. Suitable terminations include ASR33, TI733, TI 743 and VDUs at speeds between 10 and 960 cps.
(Golden River Co. Ltd., Telford Road, Bicester, Oxon, OX6 0UL, UK. Tel: Bicester 44551)

Two software packages support the COSMAC CDP1800 microprocessor family. Both systems, the RAL-II Level-II assembly language and the C-MAC macroassembler, are designed to cut development time. The RAL-II assembler, provided with the RCA's floppy-disk system, allows the assembly of COSMAC Level-II assembly language. Use of RAL-II shortens source code by about 35%, with the use of a class of special 'super-instructions'.

Also available with the floppy-disc system is the C-MAC macro-assembler, which has macroinstruction definition, conditional assembly and 'program-build'.

A range of fixed-point and floating-point binary arithmetic subroutines has also been made available. Among the packages is an implementation of the fixed-point subroutine on a 1 kbyte ROM. The software includes 31 subroutines including register save and mathematical companion operations, with arithmetic functions, format conversion and utility subroutines. The roujtines are all in 16-bit 2's-complement format.
(RCA Limited/Solid State Europe, Sunbury-on-Thames, Middlesex, Englanhd. Tel: Sunbury-on-Thames 85511. Telex: 24246).

A software package from RCA allows software development for 1802 microprocessor family to be carried out on the Intel MDS prototyping systems. This crossassembler consists of a macro file designed to run in conjunction with the Intel 8080/8085 macroassembler.

The crossassembler is designed so that the user writes his program in 1802 mnemonics, uses an MDS command to generate a suitable macrofile, and then assembles his program in the normal way to generate 1802 machine code.

For program loading into the 1802-based prototype, the user can use either an Intel EPROM programmer to develop the necessary firmware or the RCA transcoding program to load the RAM of an RCA Micromonitor, which can then be used for subsequent debugging.
(RCA Limited/Solid State Europe, Sunbury-on-Thames, Middlesex, England. Tel: Sunbury-on-Thames 85511. Telex: 24246).

RCA have just signed an agreement with Solid State Scientific Incorporated of Montgomeryville, USA, which will provide the company with artwork and tooling for the manufacture of the CDP 1802 8-bit CMOS CPU, the CDP 1822S 1-kbit silicon-on-sapphire RAM, the CDP 1824 256-bit RAM, the CDP 1831 4-kbit ROM, and the CDP 1852 8-bit I/O port.

SSS have been a large supplier of CMOS integrated circuits in the US since 1971 and will provide a viable second-source for these devices.

True full-screen editing on an integral data terminal with CRT display is featured in the COSMAC microprocessor development system, CDP18S008, from RCA Solid State for microprocessor systems based on the RCA CDP1802 and CDP 1804/5 microprocessors. The development system comprises VDU and data terminal with an ASCII keyboard with 72 standard keys and 14 special function keys; a dual floppy disc drive; 60 kbyte of user-accessible static CMOS RAM; a CDOS disc file-management and operating system; a new resident ASM8 macroassembler, editor and utility program on floppy; a plugin MOPS-augmented Micro-monitor (in-circuit emulator) for extensive online and offline debugging of both software and hardware; a builtin PROM programmer; and a builtin printer interface for RCA's new matrix high speed printer, CDP 18S050.

In single quantities, the RCA COSMAC Development System IV CDP 18S008 is priced at £s;7965.
(RCA Solid State Europe, Sunbury-on-Thames, Middlesex, TW16 7HW, UK. Tel: Sunbury-on-Thames 85511).

Computers can be large, complicated, expensive, and hard to understand. MICROTUTOR is a computer that is small, simple, inexpensive, and easy to understand. It comprises 256 words of memory, input switches, a two-digit output display, and the RCA COSMAC microprocessor.

Contrary to popular belief, computers are quite simple in concept and fun to play with. They can be useful but we'll try not to dwell on this aspect in deference to more sensitive readers. A word of caution, if MICROTUTOR makes computers seem simple to you, don't tell anyone. You can earn more money perpetuating the computer complexity myth.

Readers who insist on knowing every last little detail about COSMAC should refer to the RCA COSMAC MICROPROCESSOR MANUAL. Readers who want to be protected from actual computer hardware by software aids with names like assembler, interpreter, simulator, and compiler should save up their money for a more expensive system.

Eight switches along the bottom allow direct entry of a hexadecimal value. A pushbutton switch IN enters the value. Three more switches provide MP (Memory Protect), LD (Load) and RN (Run) functions.