Browse Prior Art Database

Customer Writeable ROM and RAM

IP.com Disclosure Number: IPCOM000075651D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Alameddine, O: AUTHOR [+2]

Abstract

The memory is a matrix consisting of the usual silicon planar transistor flip flops. The writeable read-only function is obtained by making each cell dissymmetric. This dissymmetry is produced by avalanching the base-emitter junction of one of the flip-flop transistors for a certain period of time, thus changing several of its parameters, such as Beta, I(EBO), I(CEO),BV(CEO). Especially Beta can be degraded to any wanted level, so that upon application of the operating voltage to such a dissymmetric flip-flop the nondegraded transistor will draw the cell current. This ROM function will reappear with each powering up, but has no effect on the original random access read-write capabilities of the memory.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

Customer Writeable ROM and RAM

The memory is a matrix consisting of the usual silicon planar transistor flip flops. The writeable read-only function is obtained by making each cell dissymmetric. This dissymmetry is produced by avalanching the base-emitter junction of one of the flip-flop transistors for a certain period of time, thus changing several of its parameters, such as Beta, I(EBO), I(CEO),BV(CEO). Especially Beta can be degraded to any wanted level, so that upon application of the operating voltage to such a dissymmetric flip-flop the nondegraded transistor will draw the cell current. This ROM function will reappear with each powering up, but has no effect on the original random access read-write capabilities of the memory.

As Beta degradation can be offset by drawing a strong forward current through the emitter-base junction of the stressed transistor, the ROM pattern can be rewritten several times.

1