Patent EP0529887A2 successfully refreshed from Google Patents.
EP0529887A2
Expired / Lapsed
EP
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Bidirectional parallel protocol
Assignee: Compaq Computer Corp
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Filing: 1992-08-13
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Granted: —
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Expires: 2012-08-13
Abstract
Abstract A protocol provides bidirectional communication capability between a host computer and a printer over a parallel interface, the host computer and the printer having a forward channel therebetween for the transfer of signals from the host computer to the printer. The protocol includes conventions for turning the forward channel around so as to establish a reverse channel to allow transfer of data from the printer to the host computer, conventions for controlling the transfer of data from the printer to the host computer over the reverse channel, and conventions for turning the reverse channel back around so as to re-establish the forward channel. <IMAGE>
Inventors
- 👤 Jeff D. Pipkins
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 21:00
CPC Classifications
G; G06; G06F; G06F13/00; G06F13/38; G06F13/42; G06F13/4265; G06F13/4269; G06F13/4204; G06F13/4221; G06F13/4226; G06F3/00; G06F3/12; G06F3/1201; G06F3/1202; G06F3/1211; G06F3/1223; G06F3/1236; G06F3/1278; G06F3/1284
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
104 words
A protocol for providing bidirectional communication capability between a host computer and a printer over a parallel interface, said host computer and said printer having a forward channel therebetween for the transfer of signals from said host computer to said printer, said protocol comprising: means for turning said forward channel around so as to establish a reverse channel to allow transfer of data from said printer to said host computer; means for controlling said transfer of data from said printer to said host computer over said reverse channel; and means for turning said reverse channel back around so as to re-establish said forward channel.
Claim 2
Dependent Claim
22 words
A protocol as recited in Claim 1, wherein said means for turning said forward channel around is activated by said host computer.
Claim 3
Dependent Claim
30 words
A protocol as recited in Claim 2, wherein said means for turning said reverse channel back around so as to re-establish said forward channel is activated by said host computer.
Claim 4
Dependent Claim
35 words
A protocol as recited in Claim 1, wherein said forward channel comprises status lines, and wherein said status lines are used to transfer data between said printer and said host computer during reverse channel operation.
Claim 5
Dependent Claim
41 words
A protocol as recited in Claim 1, wherein said forward channel comprises an input/output control channel, and wherein said input/output control channel is used to transfer control and status information between said printer and said host computer during reverse channel operation.
Claim 6
Dependent Claim
37 words
A protocol as recited in Claim 1, wherein said means for turning said forward channel around comprises means for said host computer to raise a *SLCTin signal, and means for said printer to lower a SLCT signal.
Claim 7
Dependent Claim
58 words
A protocol as recited in Claim 4, wherein said means for controlling transfer of data comprises means for said host computer to request a packet of data, means for said printer to indicate a packet of data is on the status lines, and means for said host computer to read the packet of data from the status lines.
Claim 8
Dependent Claim
107 words
A protocol as recited in Claim 7, wherein said packet of data comprises a nibble of data, wherein said means for said host computer to request a nibble of data comprises a *STROBE signal, and wherein said means for said printer to indicate a nibble of data is on the status lines comprises a SLCT signal, whereby a low nibble of data may be requested via a lowered *STROBE signal and indicated ready to be transmitted via a raised SLCT signal and whereby a high nibble of data may be requested via a raised *STROBE signal and indicated ready to be transmitted via a lowered SLCT signal.
Claim 9
Dependent Claim
36 words
A protocol as recited in Claim 8, further comprising means for said printer to indicate to said host computer how many bytes of data are susceptible to be transmitted from said printer to said host computer.
Claim 10
Dependent Claim
53 words
A protocol as recited in Claim 9, wherein said means for said printer to indicate to said host computer how many bytes of data are susceptible to be transmitted from said printer to said host computer acts in response to said *SLCTin signal being raised and prior to said SLCT signal being lowered.
Claim 11
Independent Claim
101 words
A method for providing bidirectional communication capability between a host computer and a printer over a parallel interface, said host computer and said printer having a forward channel therebetween for the transfer of signals from said host computer to said printer, said protocol comprising the steps of: turning said forward channel around so as to establish a reverse channel to allow transfer of data from said printer to said host computer; controlling said transfer of data from said printer to said host computer over said reverse channel; and turning said reverse channel back around so as to re-establish said forward channel.
Claim 12
Dependent Claim
22 words
A method as recited in Claim 11, wherein the step of turning said forward channel around is activated by said host computer.
Claim 13
Dependent Claim
30 words
A method as recited in Claim 12, wherein the step of turning said reverse channel back around so as to re-establish said forward channel is activated by said host computer.
Claim 14
Dependent Claim
35 words
A method as recited in Claim 11, wherein the forward channel comprises status lines, and wherein said status lines are used to transfer data between said printer and said host computer during reverse channel operation.
Claim 15
Dependent Claim
41 words
A method as recited in Claim 11, wherein the forward channel comprises an input/output control channel, and wherein the input/output control channel is used to transfer control and status information between said printer and said host computer during reverse channel operation.
Claim 16
Dependent Claim
37 words
A method as recited in Claim 11, wherein the step of turning said forward channel around comprises the step of said host computer raising a *SLCTin signal, and the step of said printer lowering a SLCT signal.
Claim 17
Dependent Claim
58 words
A method as recited in Claim 14, wherein the step of controlling transfer of data comprises the step of said host computer requesting a packet of data, the step of said printer indicating a packet of data is on the status lines, and the step of said host computer reading the packet of data from the status lines.
Claim 18
Dependent Claim
105 words
A method as recited in Claim 17, wherein the packet of data comprises a nibble of data, wherein said step of said host computer requesting a nibble of data comprises a *STROBE signal, and wherein said step of said printer indicating a nibble of data is on the status lines comprises a SLCT signal, whereby a low nibble of data may be requested via a lowered *STROBE signal and indicated ready to be transmitted via a raised SLCT signal and whereby a high nibble of data may be requested via a raised *STROBE signal and indicated ready to be transmitted via a lowered SLCT signal.
Claim 19
Dependent Claim
36 words
A method as recited in Claim 18, further comprising the step of the printer indicating to said host computer how many bytes of data are susceptible to be transmitted from said printer to said host computer.
Claim 20
Dependent Claim
52 words
A method as recited in Claim 19, where said step of said printer indicating to said host computer how many bytes of data are susceptible to be transmitted from said printer to said host computer occurs in response to said *SLCTin signal being raised and prior to said SLCT signal being lowered.
References Cited (Backward Citations)
No citation records indexed.
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