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Browse Prior Art Database

Printer Monitor/Controller

IP.com Disclosure Number: IPCOM000043302D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Smith, BA: AUTHOR

Abstract

To aid in trouble shooting system/printer problems in a computer system including a microprocessor-controlled printer, a monitor card is used to trap the printer microcode. Referring to Fig. 1, the monitor card 10 is attached in a feature slot of the computer system 12 and interconnected therewith by the internal bus. Means are provided in card 10 to connect via an external cable a printer 14 to card 10. Referring to Fig. 2, card 10 contains various LSI modules including I/O ports, an interrupt controller 16, a random-access memory (RAM) 18 and associated RAM controller 20, an electrically programmable read- only memory (EPROM) 22, latches 24, and an address decode circuit 26. Card 10 performs a function similar to that available in circuit emulators without requiring substitution of the microprocessor.

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Printer Monitor/Controller

To aid in trouble shooting system/printer problems in a computer system including a microprocessor-controlled printer, a monitor card is used to trap the printer microcode. Referring to Fig. 1, the monitor card 10 is attached in a feature slot of the computer system 12 and interconnected therewith by the internal bus. Means are provided in card 10 to connect via an external cable a printer 14 to card 10. Referring to Fig. 2, card 10 contains various LSI modules including I/O ports, an interrupt controller 16, a random-access memory (RAM) 18 and associated RAM controller 20, an electrically programmable read- only memory (EPROM) 22, latches 24, and an address decode circuit 26. Card 10 performs a function similar to that available in circuit emulators without requiring substitution of the microprocessor. The processor internal bus lines are monitored and actions taken based on matches with address and/or data patterns set up by BASIC print HEX statements. When the desired combination occurs, the interrupt controller 16 will vector the processor to the EPROM 22 which is outside the printer's address space. At this time all printer functions, i.e. wirefires, will be deactivated to prevent damage. The system will then be prepared for analysis. RAM 18 holds the previous 16K memory cycles for review. Included will be the address and data bus states and pertinent status lines. This information may be decoded to indicate the instructions execut...