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System 00

The System 00 is an early computer constructed by Joseph Weisbecker around 1971-72, when he was working at RCA. His goal was to conceive an educational computer able to play games, so that children could easily experience and understand how a computer works. This idea later evolved in FRED systems, COSMAC computers and Studio II game system.

All logic circuits in the System 00 utilize 7400 series TTL chips. Though it contains no microprocessors, the general architecture of the System 00 eventually evolved into the RCA's COSMAC 1801 chip set, and later the single-chip COSMAC 1802.

The system case houses the logic circuits, power supply, input-output interfaces, 1024 bytes of memory and a control panel. This control panel is made of many switches for binary entries and operation controls, LEDs, buttons (RUN for example) and an hexadecimal keyboard (0-9, A-F).

Memory can be expanded to 64KB max. Word length is 8 bits. Two machine cycles of 1.6 us minimum are required per instruction, resulting in a max instruction execution rate of 300K operations per second. A direct memory access channel permits independent, asynchronous input/output up to 200K bytes/sec. An external program interrupt line is also provided.

Video display is made possible through an XYZ oscilloscope. Two display modes are available: 32x32 or 16x64 matrix of dots. This requires 128 bytes of memory from the 1024 bytes available. The 16x64 mode permits 4 lines of up to 10 characters per line in 5x7 dot format.

The System 00 can be connected to a card reader. Cards are 3"x5" punched card and only one can be read at a time. The cards are manually dropped into a top slot and read photoelectrically while falling. A card is divided in two tracks (A & B). Only one track is read at a time. The "A" track is read by dropping the card in the reader with the "A" arrow down. The card is then turned around for the "B" track to be read. Each track can contain up to 12 bytes. A manual card punch is also provided.

The system 00 can also use an auxiliary "yes/no" switch box for simplefied interactions with the system and programs by unsophisticated users. The state of these switches can be read by the programs.

Programs can be entered via the hexadecimal keyboard, entering first the less significant digit, followed by the most significant digit. Programs can also be loaded via the punch card reader.