What we claim is:
1. A zoom lens system comprising in order from an object side of said zoom lens system:
a first lens group having positive refracting power,
a second lens group that has negative refracting power and moves from an object side to an image plane side of said system during zooming from a wide-angle end to a telephoto end of said system,
a third lens group having positive refracting power, and
a fourth lens group that has positive refracting power and is movable during zooming, wherein:
said first lens group comprises two lenses, a negative lens and a positive lens, or one positive lens alone,
said third lens group comprises three lenses, a positive lens, a positive lens and a negative lens, or two lenses, a positive lens and a negative lens, and
said third lens group has at least one aspherical surface therein,
provided that said zoom lens system satisfies the following condition (10):
2.5 mm<fB(min)<4.8 mm(10)
where fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
2. The zoom lens system according to claim 1, wherein the positive lens and negative lens in said third lens group are cemented together.
3. The zoom lens system according to claim 1 or 2, wherein said third lens group moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end.
4. The zoom lens system according to claim 1, wherein said first lens group remains fixed during zooming.
5. The zoom lens system according to claim 1, wherein said second lens consists of two lenses, a negative lens and a positive lens from the object side.
6. The zoom lens system according to claim 1, wherein said fourth lens group consists of one positive lens alone.
7. The zoom lens system according to claim 1, which satisfies the following condition (a):
0.3<L3L2<1.0(a)
where L2 is an amount of said second lens group from the wide-angle end to the telephoto end, and L3 is an amount of said third lens group from the wide-angle end to the telephoto end.
8. The zoom lens system according to claim 1, wherein said second lens group has at least one aspherical surface therein.
9. The zoom lens system according to claim 1, wherein said fourth lens group has at least one aspherical surface therein.
10. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming, and satisfying the following conditions (1) and (10):
0.5<F2F3<1.2(1)2.5 mm<fB(min)<4.8 mm(10)
where Fi is a focal length of an i-th lens group, and fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
11. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming, and satisfying the following conditions (2) and (10):
0.49<L3L2<1(2)2.5 mm<fB(min)<4.8 mm(10)
where Li is an amount of movement of an i-th lens group from the wide-angle end to the telephoto end, and fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
12. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming,
provided that said zoom lens system satisfies the following conditions (3) and (10):
2<(F3, 4W)IH<3.3(3)2.5 mm<fB(min)<4.8 mm(10)
where (F3, 4W) is a composite focal length of said third and fourth lens groups at the wide-angle end, IH is a radius of an image circle, and fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
13. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group having positive refracting power, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group having positive refracting power and a fourth lens group that has positive refracting power and is movable during zooming, wherein:
said third lens group comprises, in order from an object side thereof, a positive lens convex on an object side thereof and a doublet consisting of a positive lens convex on an object side thereof and a negative lens concave on an image side thereof, and peripheries of object side-directed convex surfaces of both said object-side positive lens and said doublet in said third lens group are held by a lens holder barrel while said convex surfaces are abutting at said peripheries or some points on said lens holder barrel, provided that said zoom lens system satisfies the following condition (10):
2.5 mm<fB(min)<4.8 mm(10)
where fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
14. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said system, a third lens group that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming,
provided that said zoom lens system satisfies the following conditions (1), (2) and (10):
0.5<F2F3<1.2(1)0.49<L3L2<1(2)2.5 mm<fB(min)<4.8 mm(10)
where Fi is a focal length of an i-th lens group, Li is an amount of movement of an i-th lens group from the wide-angle end to the telephoto end, and fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
15. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said system, a third lens group that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming,
provided that said zoom lens system satisfies the following conditions (1), (3) and (10):
0.5<F2F3<1.2(1)2<(F3, 4W)IH<3.3(3)2.5 mm<fB(min)<4.8 mm(10)
where Fi is a focal length of an i-th lens group, (F3, 4W) is a composite focal length of said third and fourth lens groups at the wide-angle end, IH is a radius of an image circle, and fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
16. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming,
provided that said zoom lens system satisfies the following conditions (2), (3) and (10):
0.49<L3L2<1(2)2<(F3, 4W)IH<3.3(3)2.5 mm<fB(min)<4.8 mm(10)
where Li is an amount of movement of an i-th lens group from the wide-angle end to the telephoto end, (F3, 4W) is a composite focal length of said third and fourth lens groups at the wide-angle end, IH is a radius of an image circle, and fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
17. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming,
provided that said zoom lens system satisfies the following conditions (1), (2), (3) and (10):
0.5<F2F3<1.2(1)0.49<L3L2<1(2)2<(F3, 4W)IH<3.3(3)2.5 mm<fB(min)<4.8 mm(10)
where Fi is a focal length of an i-th lens group, Li is an amount of movement of an i-th lens group from the wide-angle end to the telephoto end, (F3, 4W) is a composite focal length of said third and fourth lens groups at the wide-angle end, IH is a radius of an image circle, and fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
18. The zoom lens system according to any one of claims 10, 11, 12, and 14 to 17, which satisfies the following condition (4):
0.6<F2F3<1(4)
where Fi is a focal length of an i-th lens group.
19. The zoom lens system according to claim 17, wherein said fourth lens group moves along an optical axis direction for focusing.
20. The zoom lens system according to claim 17, which satisfies the following condition (5):
0.3<F3F4<0.8(5)
wherein Fi is a focal length of an i-th lens group.
21. The zoom lens system according to claim 17, which satisfies the following condition (6):
0.4<2T<1(6)
where 2T is a lateral magnification of the second lens group of the telephoto end of said system.
22. The zoom lens system according to claim 17, wherein said fourth lens group consists of one positive lens.
23. The zoom lens system according to claim 17, wherein said third lens group consists of three lenses, a positive lens, a positive lens and a negative lens in order from an object side thereof.
24. The zoom lens system according to claim 17, wherein at least one surface in said third lens group is an aspherical surface.
25. The zoom lens system according to claim 17, wherein at least one surface in said fourth lens group is an aspherical surface.
26. The zoom lens system according to claim 17, wherein at least one surface in said second lens group is an aspherical surface.
27. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming, wherein said first lens group consists of one positive lens, and a lens in said second lens group that is located nearest to an object side thereof is a negative lens,
provided that said zoom lens system satisfies the following conditions (7) and (10):
21<40(7)2.5 mm<fB(min)<4.8 mm(10)
where 21 is an Abbe’s number of said negative lens located nearest to the object side of said second lens group, and fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
28. The zoom lens system according to claim 27, which satisfies the following condition (8):
21<35(8)
29. The zoom lens system according to claim 17, which satisfies the following condition (7):
21<40(7)
where 21 is an Abbe’s number of the negative lens located nearest to the object side of said second lens group.
30. The zoom lens system according to claim 17, which satisfies the following condition (8):
21<35(8)
where 21 is an Abbe’s number of the negative lens located nearest to the object side of said second lens group.
31. The zoom lens system according to claim 17 or 27, wherein said third lens group comprises, in order from an object side thereof, a positive lens convex on an object side thereof and a doublet consisting of a positive lens convex on an object side thereof and a negative lens concave on an image plane side thereof, and peripheries of object side-directed convex surfaces of both said object-side positive lens and said doublet in said third lens group are held by a lens holder barrel while said convex surfaces are abutting at said peripheries or some points on said lens holder barrel.
32. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves constantly from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming, wherein said third lens group comprises a doublet consisting of a positive lens and a negative lens, and said fourth lens group comprises one positive lens,
provided that said zoom lens system satisfies the following condition (10):
2.5 mm<fB(min)<4.8 mm(10)
where fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
33. The zoom lens system according to claim 32, wherein at least one surface of the positive lens in said fourth lens group is an aspherical surface.
34. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves constantly from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming, wherein each of said second and third lens groups comprises a doublet consisting of a positive lens and a negative lens,
provided that said zoom lens system satisfies the following condition (10):
2.5 mm<fB(min)<4.8 mm(10)
where fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
35. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves constantly from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that has positive refracting power and is movable during zooming, wherein said third lens group comprises, in order from an object side thereof, a positive lens, and a doublet consisting of a positive lens and a negative lens,
provided that said zoom lens system satisfies the following condition (10):
2.5 mm<fB(min)<4.8 mm(10)
where fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
36. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power and a fourth lens group having positive refracting power, wherein during zooming, a space between said first and second lens groups, a space between said second and third lens groups and a space between said third and fourth lens groups vary independently, said third lens group comprises, in order from an object side thereof, a double-convex positive lens, and a doublet consisting of a positive meniscus lens convex on an object side thereof and a negative meniscus lens, and said fourth lens group comprises a double-convex lens having a large curvature on an object side surface thereof,
provided that said zoom lens system satisfies the following condition (10):
2.5 mm<fB(min)<4.8 mm(10)
where fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
37. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power and a fourth lens group having positive refracting power, wherein during zooming, a space between said first and second lens groups, a space between said second and third lens groups and a space between said third and fourth lens groups vary independently, said first lens group comprises one positive lens, said second lens group comprises three lenses or, in order from an object side thereof, a single lens and a doublet consisting of a negative lens and a positive lens, said third lens group comprises three lenses or, in order from an object side thereof, a single lens and a doublet consisting of a positive lens and a negative lens, and said fourth lens group comprises one positive lens,
provided that said zoom lens system satisfies the following condition (10):
2.5 mm<fB(min)<4.8 mm(10)
where fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
38. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power and a fourth lens group having positive refracting power, wherein during zooming, a space between said first and second lens groups, a space between said second and third lens groups and a space between said third and fourth lens groups vary independently, said first lens group comprises two lenses or a positive lens and a negative lens, and said second or third lens group comprises a doublet consisting of at least one set of a positive lens and a negative lens,
provided that said zoom lens system satisfies the following condition (10):
2.5 mm<fB(min)<4.8 mm(10)
where fB(min) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is minimized in an overall zooming zone.
39. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group that has positive refracting power and remains fixed during zooming, a second lens group that has negative refracting power and moves from an object side to an image plane side of said zoom lens system during zooming from a wide-angle end to a telephoto end of said zoom lens system, a third lens group that has positive refracting power and moves constantly from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group that comprises one lens component, has positive refracting power and is movable during zooming, wherein each of said second and third lens groups comprises a doublet consisting of a positive lens and a negative lens, and said third lens group or said fourth lens group has at least one aspherical surface therein.
40. A zoom lens system comprising, in order from an object side of said zoom lens system, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power and a fourth lens group having positive refracting power, wherein during zooming, a space between said first and second lens groups, a space between said second and third lens groups and a space between said third and fourth lens groups vary independently, said first lens group comprises one positive lens, said second lens group comprises three lenses or, in order from an object side thereof, a single lens and a doublet consisting of a negative lens and a positive lens, said third lens group comprises three lenses or, in order from an object side thereof, a single lens and a doublet consisting of a positive lens and a negative lens, said fourth lens group comprises one positive lens, and said third lens group or said fourth lens group has at least one aspherical surface therein.
41. The zoom lens system according to any one of claims 1, 10 to 17, 27, and 32 to 40, which satisfies the following condition (11):
2.5 mm<fB(max)<4.8 mm(11)
where fB(max) is a value obtained when a length, as calculated on an air basis, from a final surface of a powered lens in said zoom lens system to an image plane is maximized in an overall zooming zone.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of performing an emulation of an operation of a target computing system, said method comprising:
interpreting a target instruction;
recognizing an unused capacity of a host system when said host system is interpreting said instruction, as a single thread on said host system, using a plurality of concurrently-operating functional units of said host system; and
performing a translation of said instruction, in said single thread, without increasing a time of interpreting said instruction by utilizing said recognized unused capacity.
2. The method of claim 1, wherein said interpreting uses an indirect threaded interpreter in which an instruction millicode fragment comprises essential instructions required to reproduce the effect of a target instruction, and a remainder of said millicode fragment comprises instructions relating to such tasks as computing an address in a host memory or effecting a branch to a next sequential target instruction, said performing said translation comprises storing, at a new location, only the essential instructions from a host millicode.
3. The method of claim 2, wherein said millicode comprises host system instructions employed to execute intent of a single target instruction.
4. The method of claim 3, wherein each said millicode includes an instruction sequence necessary to compute an address of, and a branch to, a millicode fragment for a next target instruction to be executed,
wherein translating is performed by appending the host instructions for each target instruction onto a string of previously translated host instructions.
5. The method of claim 1, wherein said performing said translation includes utilizing empty slots in a scheduling of said instruction.
6. The method of claim 1, wherein said recognizing is performed by a scheduler.
7. The method of claim 1, wherein said performing said translation results in translated code which is created as an interpretation is performed of said instruction,
wherein a crossover between execution modes occurs only while emulation of a target branch instruction is occurring,
wherein the host system instructions included in a millicode for a branch instruction, perform operations including hashing into a profile table, and determining whether a translation has already been performed for the instructions at a location of a taken path, and, if so, then an address of the translation is stored in the profile table, and interpreting proceeds by branching to that location, and
wherein, if no translation has occurred, then the profile table returns an address of an appropriate millicode fragment, and before branching to the location, a profile table entry corresponding to a beginning of a current block for which the branch designates an end, is located, and an address of the completed translation is placed therein.
8. The method of claim 1, wherein said performing said translation produces a translation which includes a plurality of sections including a header which checks a precondition, and falls back to an interpretation if it is false, and otherwise copies in an interpreter state required for correct execution of the translation, code to effect an intent of a target instruction, and a trailer section for restoring the interpreter state and returning control to an appropriate millicode fragment,
wherein said interpretation is performed by an indirect threaded interpreter such that no loop control is performed.
9. The method of claim 1, further comprising executing said translation across branches and falling back to interpretation only when a branch exits translated code.
10. The method of claim 1, wherein in a first interpreting of said target instruction, essential instructions and other overhead instructions are stored, and in subsequent runs, only said essential instructions are accessed.
11. The method of claim 1, wherein said performing a translation of the instruction is interleaved with interpretation of the instruction such that said translation has no effect on an overall time of interpretation.
12. The method of claim 1, wherein each instruction is implemented by a fragment of millicode code which performs a plurality of tasks including at least one of:
execution of intent of a target instruction;
computation of an address of a next target instruction to be executed;
fetching of the target instruction at that address; and
lookup using the fetched target instruction as an index into a table of addresses to find a next action address and branching to the address.
13. The method of claim 1, further comprising:
using a slack time of instructions to couple together previously translated portions of code and a translated target instruction stream.
14. The method of claim 1, wherein with said translation having been performed, a shorter sequence of host instructions is stored, and subsequently when a same instruction is to be executed again, the shorter sequence is branched to in lieu of branching to the instruction action routine.
15. The method of claim 1, wherein on a first call to an instruction, the instruction is interpreted and translated, and, in subsequent calls to the instruction, the translation of the instruction is branched to.
16. The method of claim 1, further comprising:
determining, by an interpreter, whether an instruction has been interpreted, thereby to determine what mode the interpreter should be in,
said mode comprising one of an interpretive mode and a mode of executing a translation.
17. The method of claim 1, further comprising:
inserting said translation into millicode of said instruction to optimize an emulation thereof.
18. The method of claim 1, wherein said recognizing comprises exploiting said unused capacity.
19. The method of claim 1, further comprising:
enabling seamless transition between interpretation and translation by interweaving instructions for said interpretation with instructions for said translation.
20. A method of emulating an operation of a target computing system using an indirect threaded interpreter in which an instruction millicode fragment comprises essential instructions required to reproduce the effect of a target instruction, and a remainder of said millicode fragment comprises non-essential instructions relating to such tasks as computing an address in a host memory or effecting a branch to a next sequential target instruction, said method comprising:
on a host system, determining whether a translation of a millicode has been performed in accessing said millicode of an instruction having been fetched from the target computing system; and
if said translation has not been performed, then performing a translation of said millicode and arranging for access of said translation in a subsequent encounter of said instruction, such that each subsequent encounter accesses only the essential millicode of said translation.
21. A system having a processor for performing an emulation of an operation of a target computing system, said system comprising:
a recognition unit, as executed by a processor on a computer, for recognizing an unused capacity of a host system when said host system is executing an instruction as a single thread on said host system; and
a translator, as executed by said processor, for performing a translation of the instruction, in said single thread, without increasing a time of executing said instruction by utilizing said recognized unused capacity.
22. A non-transitory storage medium embodying a program of machine-readable instructions executable by a digital processing apparatus to perform a method of performing an emulation of an operation of a target computing system, comprising:
interpreting a target instruction as a single thread on a host system;
recognizing an unused capacity of said host system when said host system is interpreting said instruction; and
performing a translation of the instruction, in said single thread, without increasing a time of interpreting said instruction by utilizing said recognized unused capacity.
23. A non-transitory storage medium embodying a program of machine-readable instructions executable by a digital processing apparatus to perform a method of emulating the operation of a target computing system, using an indirect threaded interpreter in which an instruction millicode fragment comprises essential instructions required to reproduce the effect of a target instruction, and a remainder of said millicode fragment comprises instructions relating to such tasks as computing an address in a host memory or effecting a branch to a next sequential target instruction, said method comprising:
on a host system, determining whether a translation of a millicode has been performed in accessing said millicode of an instruction having been fetched from the target computing system; and
if said translation has not been performed, then performing a translation of said millicode and arranging for access of said translation in subsequent encounter of said instruction, such that each subsequent encounter accesses only the essential millicode of said translation.