Browse Prior Art Database

SIMPLIFIED SELF-PROGRAMMING TECHNIQUE FOR CMOS EPROM MICROCOMPUTERS

IP.com Disclosure Number: IPCOM000005519D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2001-Oct-11
Document File: 2 page(s) / 83K

Publishing Venue

Motorola

Related People

K. "Raghu" Raghunathan: AUTHOR

Abstract

CONTEXT Designers of EPROM microcomputers can enhance their flexibility by providing a self- programming capability. Such a "boot-strap" programming routine, typically residing in conventional mask-programmed ROM, simplifies the programming hardware by generating the addresses of the ex- ternal program data and then routing the externally-sourced program data from the input port into the internal EPROM.

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m , MOTOROLA Technlcal Developments Volume 3 March 1983

SIMPLIFIED SELF-PROGRAMMING TECHNIQUE FOR CMOS EPROM MICROCOMPUTERS

By K. "Raghu" Raghunathan

CONTEXT

   Designers of EPROM microcomputers can enhance their flexibility by providing a self- programming capability. Such a "boot-strap" programming routine, typically residing in conventional mask-programmed ROM, simplifies the programming hardware by generating the addresses of the ex- ternal program data and then routing the externally-sourced program data from the input port into the internal EPROM.

PROBLEM

   As shown in Figure 1, each EPROM programming cycle typically consists of a load (LDA) instruc- tion which loads a data byte into the accumulator register from the input port, and a store (STA) instruc- tion which stores the data byte Into a particular address location within the EPROM, with the actual programming of the EPROM occuring during clock cycle C7. If the microcomputer Is being operated at a typical clock frequency which provides a cycle time of 1 microsecond, insufficient time will be pro. vided during C7 to reliably program the EPROM. On the other hand, if the clock frequency is reduced to provide a more appropriate EPROM-programming cycle time of about 10 milliseconds, the time re- quired to program the entire EPROM will be significantly increased. One approach to solving this pro. blem is to provide additional hardware to hold the EPROM address and data during programming until a software loop has determined that the 10 milliseconds of programming time has elapsed. However, the additional 24 flip-flops (16 address, 6...