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(12) Patent: | (11) CA 1193750 |
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(21) Application Number: | 1193750 |
(54) English Title: | PROGRAM CODE FETCH ARRANGEMENT |
(54) French Title: | DISPOSITIF D'EXTRACTION DE CODES DE PROGRAMME |
Status: | Term Expired - Post Grant |
(51) International Patent Classification (IPC): |
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(72) Inventors : |
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(73) Owners : | |
(71) Applicants : | |
(74) Agent: | R. WILLIAM WRAY & ASSOCIATES |
(74) Associate agent: | |
(45) Issued: | 1985-09-17 |
(22) Filed Date: | 1983-06-16 |
Availability of licence: | Yes |
Dedicated to the Public: | N/A |
(25) Language of filing: | English |
Patent Cooperation Treaty (PCT): | No |
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(30) Application Priority Data: | ||||||
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PROGRAM CODE FETCH ARRANGEMENT
ABSTRACT OF THE DISCLOSURE
The present invention permits any number of pages of
data memory to contain program code without the loss of access to
the corresponding page of the program code memory. The memory
select lead derived from a central processor's control leads is
employed by the memory decoding circuitry to distinguish between a
program code and a data fetch. This arrangement forces the memory
to produce a code fetch from data space of memory, when any one of
the pages dedicated to program code is accessed. A fetch control
circuit is included between the central processing unit and
memory. This fetch circuit obtains program code from the data
space in memory when a latch of an input/output port controlled by
the central processor unit is set, indicating that a program
request is to come from data memory and one of the pages of memory
containing program code in the data space is referenced As a
result, the memory decoding circuitry detects this request for a
fetch as a data fetch, although the processor indicated the fetch
as a program code fetch. If the input/output port is not set by
the CPU to force a program fetch from data space in memory,
program code from the program code memory will be fetched.
Note: Claims are shown in the official language in which they were submitted.
Note: Descriptions are shown in the official language in which they were submitted.
Sorry, the representative drawing for patent document number 1193750 was not found.
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Description | Date |
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Inactive: Expired (old Act Patent) latest possible expiry date | 2003-06-16 |
Inactive: Reversal of expired status | 2002-09-18 |
Inactive: Expired (old Act Patent) latest possible expiry date | 2002-09-17 |
Grant by Issuance | 1985-09-17 |
There is no abandonment history.
Note: Records showing the ownership history in alphabetical order.
Current Owners on Record |
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None |
Past Owners on Record |
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ROBERT C. WEBBER |