RCA CDP18S711 manual The Power Supply

6 RCA COSMAC VIP Instruction Manual

CHIP-8 includes a real time clock, random number generator, decimal conversion, and digit or graphic display capability. It only uses 512 bytes of RAM leaving over 1024 bytes for programs in a 2048-byte system. (You can get an additional 2048 bytes of RAM by plugging four more RAM chips into your card.)

With the aid of the User Manual for the CDPI802 COSMAC Microprocessor, MPM-201, you can explore the fascinating world of machine language programming. You can even combine, machine language programs with CHIP-8 programs or develop your own interpretive languages.

For hardware hackers, COSMAC VIP provides complete external interface capabilities. Some suggestions for inexpensive external devices and applications are listed in Section VI. Logic diagrams, data sheets, trouble -shooting hints, and test programs are provided so that you can explore the hardware in as much detail as you want.

This manual assumes that you are familiar with computer basics from reading one or more of the excellent magazines devoted to home computing. You should understand RAM, ROM, memory addressing, instructions, bytes, etc. The use of a scope

will facilitate setting up the cassette system and iden- tifying hardware problems in the rare case where they occur. Hex notation is used in this manual unless noted otherwise. (One byte equals two hex digits.)

The Power Supply

The output wires of the internally regulated power converter supplied with the COSMAC VIP CDP18S711 are connected to the +V DC and GND pads at the back left comer of the PC card. The power converter output is regulated +5 V DC at 600 mA. If you wish to add more RAM to your system, however, you may need a higher-current power supply. A 2048-byte system requires about 350 mA (600 mA worst case). A 4096-byte system should require average current of about 600 mA. If, however, your RAM chips require above average power, you may need to supply as much as 900 mA at 5 V DC, regulated. You can also use your own unregulated 8 to 10 V DC power supply by adding voltage regulator U28 (plus heatsink) to your COSMAC VIP card and cutting the printed circuit link called LKI. Never apply more than +5 V DC to the card unless the U28 regulator has been added and link LKI cut.

Photograph of COSMAC VIP (Video Interface Processor) CDP18S711 The cables in the upper right are for the video display and for cassette operation. Cable on the upper left goes to the power converter.