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Claims  |
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What is claimed is:
1. An information processing system having a CPU and a main program and
data storage unit, comprising:
auxiliary storage interface means for transferring data between said CPU
and auxiliary storage devices, being configured to access at least one
auxiliary magnetic storage device;
semiconductor storage means connected to said auxiliary storage interface
means, for receiving, storing, and retrieving data and programs;
BIOS storage means coupled to said CPU and said semiconductor storage means
for storing at least a portion of a BIOS that controls said semiconductor
storage means so as to respond to said auxiliary storage interface means
in the same manner as said auxiliary magnetic storage device;
determination means, coupled to said semiconductor storage means, for
determining a storage capacity of said semiconductor storage means and for
outputting one of a first and second signal indicative of said
determination;
detection means, coupled to said determination means, for detecting when
said semiconductor storage means is to be treated as one of a floppy disk
type and hard disk type magnetic storage, said detection means, upon
receiving said first signal from said determination means, detecting that
said semiconductor storage means is to be treated as said floppy disk-type
magnetic storage, and said detection means, upon receiving said second
signal from said determination means, detecting that said semiconductor
storage means is to be treated as said hard disk type magnetic storage;
and
ID information storage means, connected to said semiconductor storage means
and said detection means, for storing ID information used by said BIOS
storage means to initialize and configure said semiconductor storage means
in one of a plurality of predetermined storage formats corresponding to
the type detected by said detection means.
2. The information processing system according to claim 1 wherein said
semiconductor storage means stores a program including an access request
to said auxiliary magnetic storage device memory means.
3. The information processing system according to claim 2 wherein said
semiconductor storage means has a read-only memory and an erase/write
memory, said information processing system including means for copying a
portion of contents of said read-only memory to said erase/write memory.
4. The information processing system according to claim 3 further
comprising means for translating between physical addresses of source and
target memory locations when access is made to said semiconductor storage
means.
5. The information processing system according to claim 2 wherein access to
said semiconductor storage means is accomplished using translation means
for translating an address for said auxiliary magnetic storage device to
an address for said semiconductor storage means.
6. The information processing system according to claim 5 wherein said
semiconductor storage means stores track ID information designated for
said auxiliary magnetic storage device, said translation means employing
said track ID information to make said address translation.
7. The information processing system according to claim 1 wherein access to
said semiconductor storage means is accomplished using translation means
for translating an address for said auxiliary magnetic storage device to
an address for said semiconductor storage means.
8. The information processing system according to claim 7 wherein said
semiconductor storage means has a read-only memory and an erase/write
memory, said information processing system including means for copying a
portion of contents of said read-only memory to said erase/write memory.
9. The information processing system according to claim 8 further
comprising means for translating between physical addresses of source and
target memory locations when access is made to said semiconductor storage
means.
10. The information processing system according to claim 7 wherein said
semiconductor storage means stores track ID information designated for
said auxiliary magnetic storage device, said translation mens employing
said track ID information to make said address translation.
11. The information processing system according to claim 10 wherein said
semiconductor storage means has a read-only memory and an erase/write
memory, said information processing system including means for copying a
portion of the contents of said read-only memory to said erase/write
memory.
12. The information processing system according to claim 1 wherein said
semiconductor storage means has a read-only memory and an erase/write
memory, said information processing system including means for copying a
portion of the contents of said read-only memory to said erase/write
memory.
13. The information processing system according to claim 12 further
comprising means for translating between physical addresses of source and
target memory locations when access is made to said semiconductor storage
means.
14. The information processing system of claim 1 further comprising:
address translation means for translating auxiliary magnetic storage
addresses to corresponding semiconductor storage addresses for accessing
said semiconductor storage means.
15. The information processing system of claim 14 wherein:
said auxiliary magnetic storage addresses correspond to values for a total
number of cylinders, heads, and sectors, a desired sector being addressed,
and a sector length; and
said address translation means translates to addresses in said
semiconductor storage means corresponding to the value of a product of the
number of magnetic storage sectors and twice the cylinder number added to
the number of heads and then added to one less than the sector number
being addressed all multiplied by 128 and by a factor of 2 raised to the
power of the desired sector length, and further summed with a
predetermined minimum offset value determined by a memory size for storing
track ID information.
16. The information processing system of claim 15 wherein the value of the
sector size is first doubled prior to said translation.
17. The information processing system of claim 1 further comprising:
memory translation means for translating between read-only and erase/write
memory physical addresses when access is made to said semiconductor
storage means.
18. Semiconductor storage for use in an information processing system
having a CPU, a main storage for programs and data, and configured to
access auxiliary storage devices, comprising:
auxiliary storage interface means for transferring data between said CPU
and auxiliary storage devices, being configured to access at least one
auxiliary magnetic storage device;
semiconductor storage means connected to said auxiliary storage interface
means, for receiving, storing, and retrieving data and programs;
BIOS storage means coupled to said CPU and said semiconductor storage means
for storing at least a portion of a BIOS that controls said semiconductor
storage means so as to respond to said auxiliary storage interface means
in the same manner as said auxiliary magnetic storage device;
determination means, coupled to said semiconductor storage means, for
determining a storage capacity of said semiconductor storage means and for
outputting one of a first and second signal indicative of said
determination;
detection means, coupled to said determination means, for detecting when
said semiconductor storage means is to be treated as one of a floppy disk
type and hard disk type magnetic storage, said detection means, upon
receiving said first signal from said determination means, detecting that
said semiconductor storage means is to be treated as said floppy disk-type
magnetic storage, and said detection means, upon receiving said second
signal from said determination means, detecting that said semiconductor
storage means is to be treated as said hard disk type magnetic storage;
and
ID information storage means, connected to said semiconductor storage means
and said detection means, for storing ID information used by said BIOS
storage means to initialize and configure said semiconductor storage means
in one of a plurality of predetermined storage formats corresponding to
the type detected by said detection means.
19. A method for providing semiconductor type auxiliary storage for an
information processing system having a CPU and a main program and data
storage unit, the method comprising the steps of:
providing an auxiliary storage interface for transferring data between said
CPU and auxiliary storage devices, said auxiliary storage interface being
configured to access at least one auxiliary magnetic storage device;
connecting at least one semiconductor memory device to said auxiliary
storage interface for receiving, storing, and retrieving data and
programs;
providing a least a portion of a Basic Input/Output Operating system (BIOS)
in communication with both said CPU and said auxiliary storage interface
for controlling said semiconductor memory device so as to respond to said
auxiliary storage interface in the same manner as said auxiliary magnetic
storage device;
determining a storage capacity of said semiconductor memory device and
outputting a first and second signal indicative of said determination;
detecting when said semiconductor memory device is to be treated as one of
a floppy disk type and hard disk type magnetic storage, wherein upon
receiving said first signal being outputted in said determining and
outputting step, detecting that said semiconductor memory device is to be
treated as said floppy disk type magnetic storage, and wherein upon
receiving said second signal being outputted in said determining and
outputting step, detecting that said semiconductor memory device is to be
treated as said hard disk type magnetic storage;
storing ID information comprising predetermined operating parameters for a
plurality of magnetic storage formats corresponding to the type detected
in said detecting step; and
initializing said semiconductor memory device using said BIOS so as to
configure said semiconductor memory device in one of said plurality of
storage formats based upon the type detected in said detecting step.
20. The method of claim 19 further comprising the steps of:
translating addresses requested for said auxiliary magnetic storage device
to semiconductor memory addresses when data transfers are effected through
said auxiliary storage interface; and
executing the translated request.
21. The method of claim 20 wherein said addresses are translated by adding
an offset value, so as to reserve upper memory addresses for storage of
said ID information, to a product of the sector size in bytes for the
magnetic storage device being accessed and a quantity equal to the number
of tracks prior to a current track being accessed for said magnetic
storage device times the number of sectors per track which is then summed
with one less than the sector number being addressed on the current track.
22. The method of claim 21 wherein the value of the sector size is adjusted
to correspond to a desired size for storage media in said auxiliary
magnetic storage device prior to said translation.
23. A method of utilizing semiconductor type auxiliary storage in an
information processing system while permitting the utilization of existing
software configured for use with conventional magnetic storage memory,
comprising the steps of:
providing a semiconductor storage device for receiving, storing, and
retrieving data and programs and having ID information stored therein
corresponding to memory format structures for said conventional magnetic
storage memory;
determining a relative storage capacity for said semiconductor storage
device and providing a first and second signal indicative of said
determination;
selecting a predetermined one of said memory format structures based on
said ID information for said semiconductor storage device in response to
the determined capacity by treating said semiconductor storage device as a
floppy disk type magnetic storage when said first signal is provided in
said determining and providing step, and treating said semiconductor
storage device as a hard disk type magnetic storage when said second
signal is provided in said determining and providing step;
initializing said semiconductor storage device to configure said
semiconductor storage device in one of said memory format structures based
upon the memory format structure selected in the selecting step;
capturing access requests for said conventional magnetic storage memory;
translating addresses in the access requests to addresses for said
semiconductor storage device by employing said ID information; and
executing the translated access requests.
24. The method of claim 23 wherein said address is translated by adding a
predetermined offset value, which reserves upper memory storage for said
ID information, to a product of the sector size in bytes for the type of
magnetic storage being accessed and a quantity equal to the number of
tracks prior to a current track being accessed for said magnetic storage
times the number of magnetic storage sectors per track and then added to
one less than the sector number being addressed on the current track.
25. The method of claim 24 wherein the value of the sector size is adjusted
to correspond to a desired size for storage media in said auxiliary
magnetic storage device prior to said translation. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
This invention relates generally to an information processing system of a
relatively small size such as a personal computer, and more particularly
to an information processing system having compact high speed auxiliary
storage for data and programs.
A conventional information processing system is generally configured as
shown in FIG. 14. Such a system comprises a central processing unit (CPU)
1 which is the heart of the system. CPU 1 is connected through system bus
26 to main storage 2 where programs and data transferred from the
auxiliary storage and intermediate results of program execution are
stored, read-only memory (ROM) 3 which stores a basic input/output system
(BIOS), keyboard 4 which functions as an input device to the system,
display 5 which functions as an output device, a hard disk 6, and a floppy
disk 7 which function as auxiliary storage for programs and data.
When power is applied to the system, the system is reset and initialized
and CPU 1 executes an initial load program (ILP) stored in BIOS ROM 3 to
transfer other programs from hard disk 6 or the floppy disk 7 to main
storage 2. Thereafter, CPU 1 executes programs transferred to main storage
2 to accomplish the objectives of the programs.
Magnetic storage such as hard disk 6 or floppy disk 7 which are employed as
auxiliary storage has a limit in terms of its possible size, weight and
power consumption reduction. As a result, the presence of magnetic storage
imparts a large restriction on the realization of a compact information
system featuring actual portability.
Since the prior art floppy disk or hard disk drives include a mechanical
rotary portion and a mechanical operation for moving a read/write head
relative to a magnetic medium, access time can be necessarily long and the
operation of the drive slow. Further, the mechanical operation involved
during the access operation is noisy.
Beside the forgoing disadvantages, it is known that magnetic storage is
relatively weak with respect to strong magnetic field and high temperature
and humidity environments.
In order to avoid the problems encountered with magnetic storage, attempts
have been made to use semiconductor based storage by following two
different approaches. In the first approach, an application program, i.e.,
a data processing program which allows a user to visually interact with
the program and confirm results, switches banks of the semiconductor
auxiliary storage and access to the semiconductor auxiliary storage is
accomplished deemed as a part of the main system storage. In the second
approach, the access is made through a device drive program, i.e., a
device driver, as a specific auxiliary storage and functions as a part of
the operating system (OS).
However, in the first approach, the application program is designed to have
a high dependency on a particular type and kind of memory. An existing
application program is usually created and prepared on the assumption that
a hard or floppy disk is employed as the auxiliary storage. Thus, it is
necessary to modify the application program so that it may be employed
with semiconductor type auxiliary storage.
In the second approach, after the device driver is activated, the
semiconductor storage device is set in its activated condition. A BOOT
program is stored in semiconductor device and the main body or software
cannot be set up as part of establishing an active condition. Therefore,
it is not possible to store the OS itself in semiconductor auxiliary
storage, nor to incorporate a medium copy program, i.e., copied into such
storage, or from a floppy disk to floppy disk and, further, is dependent
on a BIOS which is highly dependent on the OS.
It is an object of the present invention to solve the above mentioned
problems.
It is another object of this invention to provide a compact, light weight,
highly reliable, and high speed information processing system while
permitting the utilization of existing software applications and programs
created and written for use with particular conventional memory devices,
such as floppy disk or hard disk magnetic memories.
SUMMARY OF THE INVENTION
According to this invention, an information processing system constructed
according to the present invention employes a semiconductor type auxiliary
storage. A basic input/output program stored in the main body of the
system accesses the semiconductor auxiliary storage when it receives an
address request for magnetic type auxiliary storage or memory devices,
which request originates from the execution of one or more host programs.
The accessing is accomplished by translating the address for the magnetic
storage into an address for the semiconductor auxiliary storage. The
address translation is in turn accomplished by utilizing ID information
for the magnetic storage which has previously been written into a
predefined portion of the semiconductor auxiliary storage. The basic
input/output program converts the access request for magnetic storage
received from application software or a disk operating system (DOS) into
an access request for semiconductor auxiliary storage and executes the
request. An address for the semiconductor auxiliary storage is obtained by
reading out corresponding ID information based on the address for the
magnetic storage and processing the ID information and the address for the
magnetic storage into a predetermined mathematical relationship.
It is preferred that the semiconductor auxiliary storage contains both
read-only storage and erase/write storage capability and that the
information processing system includes means for copying a portion of the
contents of the read-only storage of the semiconductor auxiliary storage
area into the erase/write storage. When an access is made to the
semiconductor auxiliary storage having a portion of the contents of the
read-only storage copied into the erase/write storage, it is preferred
that the information processing system includes elements for translating
physical addresses of a source area to a physical address of a target
area. When the portion of the contents of the read-only storage in the
semiconductor auxiliary storage has been copied into the erase/write
storage and an access request is issued to the ROM source area, access is
effected by employing a sum of the base address and a value determined by
the capacity of the copied into area as a physical address for the
erase/write area. In this manner, access is effected for the target
storage area. Further, when an access is made to the semiconductor
auxiliary storage, means may be provided for determining whether the
semiconductor auxiliary storage is to be handled as floppy disk type or
hard disk type magnetic storage based on a determination of the capacity
of the semiconductor auxiliary storage.
It is preferable that the semiconductor auxiliary storage be constructed
for easily removable mounting in the information processing system.
Other objects and attainments together with a fuller understanding of the
invention will become apparent and appreciated by referring to the
following description and claims taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of one embodiment of an information processing
system comprising the present invention.
FIG. 2 is a block diagram of an internal configuration of semiconductor
auxiliary storage employed relative to this invention.
FIGS. 3A, 3B, 3C illustrate stored capacity information by memory type in a
control register.
FIG. 4 is a hierarchy block diagram of the system configuration for the
embodiment shown in FIG. 1.
FIG. 5 is a flow chart of read and write processing for the BIOS to a
software interrupt INT1H.sub.H from a DOS.
FIG. 6 illustrates a stored ID information.
FIG. 7 is a memory space in the semiconductor auxiliary storage.
FIG. 8 is a flow chart of read and write processing for the BIOS to the
software interrupt INT1B.sub.H from the DOS for selecting a processing
procedure based on the capacity of the semiconductor auxiliary storage.
FIG. 9 is a flow chart of a process for determining a capacity for each
memory type of semiconductor auxiliary storage.
FIGS. 10A, 10B, 10C illustrate a relationship among a data format, a memory
type, and a logical address in the memory space of semiconductor auxiliary
storage.
FIG. 11 is a flow chart of a copy process.
FIG. 12 is a flow chart of a translation process from a logical address to
a physical address.
FIG. 13 is a flow chart of a format track process.
FIG. 14 is a block diagram of a prior art information processing system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1 an information processing system 1 constructed
according to this invention is shown comprising CPU 1A, main storage 2,
BIOS ROM 3, keyboard 4, display 5, semiconductor storage 9, expansion
floppy disk 10 and expansion hard disk 11 all connected to system bus 26.
Main storage 2 and BIOS ROM 3 are sometimes referred to collectively as
the main storage of system 1 but they are referred to separately herein.
CPU 1, main storage 2, keyboard 4, and display 5 are identical to those
employed in the conventional information processing system shown in FIG.
14. The physical structure of BIOS ROM 3 is also identical to a
conventional BIOS but the program contents stored therein differs in part
because of the necessity to drive and control semiconductor auxiliary
storage 9 instead of hard disk 6 and floppy disk 7 as in a conventional
system. Expansion floppy disk 10 and expansion hard disk 11 may be added
as required in order to support the operation of semiconductor auxiliary
storage 9. For example, these expansion disks may be added when
semiconductor auxiliary storage 9 is insufficient alone for meeting the
memory capacity required for implementing auxiliary storage. On the other
hand, these expansion disks are not always necessary.
FIG. 2 is a block diagram of an internal configuration of semiconductor
auxiliary storage 9. Semiconductor auxiliary storage 9 comprises memory
circuit 21 including a semiconductor integrated circuit, data register 22,
address register 23, and control register 24. Memory circuit 21 contains
two types of memories: a read-only memory (ROM) and an erase/write memory
(RAM). Semiconductor auxiliary storage 9 is physically supported on a
structure generally referred to as an IC card. It has a card-like plate
structure, and when it is plugged into a connector 25 connected to system
bus 26, electrical connection is made to system bus 26. In FIG. 2, only
one semiconductor auxiliary storage 9 is illustrated for purposes of
simplification but a plurality of such storage structures are usually
provided so that a large amount of data may be stored among semiconductor
auxiliary storages, or separate semiconductor auxiliary storages are
employed for storing software programs as well as for storing data.
The functional operation of auxiliary storage 9 is generally as follows.
Address register 23 designates an address in memory circuit 21. A start
address for use by CPU 1 in accessing memory circuit 21 is set by CPU 1 in
address register 23 through system bus (I/O bus) 26. After the start
address has been set in address register 23, data is written to data
register 22 and the data is automatically written into that address in
memory circuit 21. When the data is written into data register 22, address
register 23 is automatically incremented so that data can be written to
the next address. Similarly, when the start address is set in address
register 23 and data is read from data register 22, the data is
automatically read from that address of memory circuit 21. When the data
is read, address register 23 is automatically incremented and data can be
read out from the next address.
Control register 24 stores an identification code or device information
indicative of the memory type of semiconductor auxiliary storage 9. FIG. 3
shows a storage of contents status in control register 24 of the memory
capacity by memory type which is a portion of the relevant device
information for semiconductor auxiliary storage 9. FIG. 3A shows a type
register which indicates the memory type for memory circuit 21. When bit 0
(MK0) of the register is "1", this indicates that the memory type for
memory circuit 21 is a RAM. Similarly, bit 1 (MK1) indicates a mask ROM,
bit 2 (MK2) indicates a P-ROM, and bit 3 (MK3) indicates an EEPROM.
FIG. 3B shows a capacity register which indicates an erase/write memory
capacity for memory circuit 21. When bit 0 (WC0) of the register is "1",
this indicates that the erase/write capacity is 64 kilo bytes (KB).
Similarly, bit 1 (WC1) indicates 128 KB, bit 2 (WC2) indicates 256 KB, bit
3 (WC3) indicates 512 KB, bit 4 (WC4) indicates 1 MB, bit 5 (WC5)
indicates 2 MB, bit 6 (WC6) indicates 4 MB, and bit 7 (WC7) indicates 8
MB.
FIG. 3C shows a capacity register which indicates the read-only memory
(ROM) capacity of memory circuit 21. When bit 0 (VC0) of this register is
"1", this indicates that the ROM capacity is 64 KB. Similarly, bit 1 (UC1)
indicates 128 KB, bit 2 (UC2) indicates 256 KB, bit 3 (UC3) indicates 512
KB, bit 4 (UC4) indicates 1 MB, bit 5 (UC5) indicates 2 MB, bit 6 (UC6)
indicates 4 MB, and bit 7 (UC7) indicates 8 MB. The contents of those
registers are detected by reading out a specific I/O port address of the
information processing system 1 and the memory type and the memory
capacity of semiconductor auxiliary storage 9 which is currently loaded
can be determined based on the contents of these registers.
As previously indicated, semiconductor auxiliary storage 9 is removably
mounted onto system bus 26 through connector 25. Auxiliary storage 9,
therefore, may be exchanged for use relative to each program or data
stored in auxiliary storage 9 as in the case of a conventional floppy
disk. Since auxiliary storage 9 is of a card shape, by utilizing
semiconductor integrated circuits for memory storage, it is easy to
transport and handle. Since a ROM is used entirely or partially in memory
circuit 21, a single piece of software may be copied in volume as compared
to one-to-one copy in the case of a floppy disk. Accordingly, this
approach is effective for the distribution of software.
The operation of information processing system 1 according to the present
embodiment will now be explained.
FIG. 4 shows a hierarchy type block diagram of the system configuration of
system 1 relative to operation in a file access mode. Application software
41 exists at the top level of the hierarchy. Next is disk operating system
(DOS) 42 which handles software interruptions due to file input/output
requests from application software 41. Below DOS 42 is a basic
input/output system (BIOS) 43 which is firmware that controls the lower
level input/output operations relative to operation of hardware 44. The
general configuration of hardware 44 is shown in FIG. 1. CPU 1 may, for
example, be an Intel 16 bit microprocessor 8086. DOS 42 may be Microsoft
MS-DOS. BIOS 43 may be one of the input/output systems of the disk
requested by the software interrupt INTIB.sub.H from DOS 42. BIOS 43 is
stored in BIOS ROM 3 together with an IPL and it operates under the
control of CPU 1. DOS 42 and application software 41 are generally stored
in semiconductor auxiliary storage 9 and they are transferred to main
storage 2 and executed by CPU 1. DOS 42 may be stored in BIOS ROM 3.
When the information processing system shown in FIG. 1 is started, CPU 1
executes the IPL stored in BIOS ROM 3 and transfers DOS 42 stored in
semiconductor auxiliary storage 9 to main storage 2. Then, CPU 1 transfers
application software 41 also stored in semiconductor auxiliary storage 9,
to main storage 2, and the application software is executed under the
control of DOS 42.
Application software 41 and DOS 42 are prepared on the assumption that the
magnetic storage, such as the floppy or hard disk, is employed as
auxiliary storage. Accordingly, BIOS 43 is requested by DOS 42 or
application software 41 to access the floppy disk or hard disk. However,
BIOS 43 converts the access request for magnetic storage to an access
request for semiconductor auxiliary storage 9 in the following manner.
Accordingly, DOS 42 and application software 41 see the auxiliary storage
as the magnetic storage but, in fact, it is semiconductor auxiliary
storage 9. In other words, in the present system, semiconductor auxiliary
storage 9 is treated as if it is the magnetic storage or memory means. As
a result, information processing system 1 makes use of existing
application software without any need or requirement for changing its
contents including any adaptation to interface with semiconductor
auxiliary storage 9.
FIG. 5 is a flow chart of the read and write processing of BIOS 43 for
software interrupt INT1B.sub.H from DOS 42. When application software 41
issues a file input/output request to DOS 42, DOS 42 determines what drive
is associated with that file and issues the software interrupt,
INT1B.sub.H, to BIOS 43. DOS 42 requests BIOS 43 for access to either the
floppy disk or the hard disk. BIOS 43 determines the drive associated with
the request (step 101), i.e., it determines a drive number and determines
if the request is to semiconductor auxiliary storage 9, which is treated
as if it were the floppy disk or the hard disk, or to expansion floppy
disk 10 or to expansion hard disk 11. If the request is for access to
expansion floppy disk 10 or expansion hard disk 11, the normal read/write
process for software interrupt INT1B.sub.H is executed (step 106). If the
request is for access to semiconductor auxiliary storage 9, the contents
of the ID information stored in semiconductor auxiliary storage 9 are
examined to determine if the correct ID information has been formatted
(step 102). The ID information is track ID information which would
normally be written in a magnetic auxiliary storage or memory means. It is
the information necessary for BIOS 43 to translate the disk address to an
address in semiconductor auxiliary storage 9. If the ID information has
not been formatted, the address translation cannot be carried out and an
error process is carried out (step 105) instead. The ID information will
be explained in detail later. If the ID information has been correctly
formatted, the disk address (cylinder number, surface number and sector
number) is translated into an address in semiconductor auxiliary storage 9
based on the contents of the ID information stored in semiconductor
auxiliary storage 9 (step 103), and input/output processing is carried out
(step 104). The address translation in step 103 will be explained in
detail later.
Using a discrimination function to determine whether or not BIOS 43
requests access to semiconductor auxiliary storage 9 and the address
translation and input/output functions for semiconductor auxiliary storage
9 by reference to ID information, application software 41 and DOS 42 need
not be concerned that semiconductor auxiliary storage 9 is employed as the
auxiliary storage rather than conventional magnetic storage memory
elements. It can be treated as if the floppy disk or the hard disk is
employed as the auxiliary storage.
Referring to FIG. 6, the track ID information for the magnetic storage is
now explained. In this particular example, semiconductor auxiliary storage
9 is treated as a 640 KB floppy disk. FIG. 6 shows a format for the ID
information stored in the first 1 KB area of conductor auxiliary storage
9. The ID information includes four bytes, one byte for each cylinder
number (C), surface number (H), number of sectors (R) and length of a
sector (N) for each track. The cylinder number (C) is usually written in
an ID area in one sector of one track of a floppy disk, and the surface
number (H) is also written in the ID area of the floppy disk. The surface
number "00" indicates a front surface and "01" indicates a rear surface.
The number of sectors (R) indicates the number of sectors in a track. In
the present embodiment, the number of sectors is eight for each track. The
sector length (N) indicates the sector length in accordance with a sector
length code as shown in Table 1. Bit 7 indicates whether the disk
designated as single density or double density. In the present embodiment,
each track is configured as single density and has 512 bytes.
TABLE 1
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N 0 1 2 3 4
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SECTOR LENGTH
128 256 512 1024 2048
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N 5 6 7 8 OR LONGER
______________________________________
SECTOR LENGTH
4096 8192 16384 32768
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In FIG. 6, numbers in the leftmost column indicate the top address of the
ID information for the respective tracks. As many 4-byte ID information
designations for the tracks are provided as are needed to match the number
on tracks of virtual floppy disk, and entire track ID information 61
having the same data content as that of last track ID information 60 is
stored in the last four bytes of the top 1 KB of memory. The top address
(hexadecimal 27C in the present illustration) of last track ID information
60 can be calculated based on entire track ID information 61 using the
following relationship:
(C.times.2.times.H).times.4 Top Address.
By letting the cylinder number C=4F and the surface number H=1, the result
is:
(4F.times.2+1).times.4=27C.
The translation from a standard disk address to an address on semiconductor
auxiliary storage 9 is explained next. Memory space on semiconductor
auxiliary storage 9 is allocated as shown in FIG. 7. The ID information
shown in FIG. 6 is stored in the top 1 KB of the auxiliary memory and data
is stored in subsequently designated areas in order of track number.
The translation of a disk address to an address on semiconductor auxiliary
storage 9 by BIOS 43 is carried out in the following manner after
verifying that ID information stored in the top 1 KB of semiconductor
auxiliary storage 9 memory has been correctly formatted. First, based on
parameters Ci and Hi relating to the cylinder number and the surface
number, which are portions of the disk address delivered from the software
interrupt INT1B.sub.H, the top address of the ID information of the
corresponding track is calculated according to the following relationship:
(Ci.times.2+Hi).times.4 Top Address
For example, by setting Ci=1 and Hi=1, which represent the third track the
value "DOC" is obtained. Then, based on a parameter Ri relating to the
sector number, which is also a portion of the disk address delivered from
the software interrupt INT1B.sub.H, the cylinder number (C), the surface
number (H), the number of sectors (R) and the sector length (N) are all
obtained by accessing the top address of the ID information which is
calculated in accordance with the above relationships. An input/output
address of semiconductor auxiliary storage 9 corresponding to the disk
address is then calculated in accordance with one of the following
relationships (1) or (2):
DA400H+{(C.times.2+H).times.R+Ri-1}.times.128.times.2.sup.n (1)
DA400H+(C.times.2+H).times.R.times.128.times.2.sup.N
.times.2+(Ri-1).times.128.times.2.sup.N (2)
Formula (1) applies to double density disk while formula (2) applies to
single density disks. The single and double density disks can be
distinguished using bit 7 of the sector length, as previously described.
In formulas (1) and (2), 400H (where H represents a hexadecimal number)
indicates the top 1 KB in which the ID information is stored,
(C.times.2+H) indicates the number of tracks positioned before the track
in question, based on the assumption that there are two surfaces,
(C.times.2+H). R indicates a sum of the number of sectors positioned
before the track in question, and 128.times.2.sup.N indicates the sector
length in bytes in accordance with Table 1. The difference between
relationships (1) and (2) is that the number of sectors (R) for single
density is one half that of double density.
In the present embodiment, semiconductor auxiliary storage 9 is employed as
a floppy disk. It may also be employed as a hard disk in accordance with
the same philosophy. In this latter case, the ID information for a hard
disk is written into semiconductor auxiliary storage 9. When an access
request to the hard disk is issued for BIOS 43, BIOS 43 accesses
semiconductor auxiliary storage 9 to deliver the fetched data to DOS 42 or
application software 41 as if it is the requested data from the hard disk.
Semiconductor auxiliary storage 9 is removable through use of connector 25
as explained in connection with FIG. 2. As a result, a semiconductor
auxiliary storage of an appropriate capacity may be selectively loaded
depending on the specific application. Usually, a hard disk has a larger
capacity than a typical floppy disk. Thus, when semiconductor auxiliary
storage 9 has a relatively large capacity is employed as a hard disk and
when semiconductor auxiliary storage 9 has a relatively small capacity it
is employed as a floppy disk. In processing the software interrupt
INT1B.sub.H of BIOS 43, whether the semiconductor auxiliary storage is to
be treated as a hard or floppy disk is determined by the capacity of
semiconductor auxiliary storage 9.
FIG. 8 is a flow chart of steps used in processing software interrupt
INT1B.sub.H of BIOS 43. When application software 41 presents a file
input/output request to DOS 42, DOS 42 issues the software interrupt
INT1B.sub.H to BIOS 43. BIOS 43 determines which device the request was
issued from in order to determine whether or not it is to semiconductor
auxiliary storage 9 (step 201). If it is not to semiconductor auxiliary
storage 9, then normal INT1B.sub.H processing is carried out (step 205) as
is known in the art. If the interrupt request it is directed to
semiconductor auxiliary storage 9, the capacity thereof is examined to
determine if it is less than 1 MB (step 202). If the capacity is less than
1 MB, an input/output process to treat semiconductor auxiliary storage 9
as a floppy disk is carried out (step 203). The step 203 in FIG. 8
corresponds to the process steps designated by dotted line box 110 of FIG.
5. In step 202, if the memory capacity is determined to be more than 1 MB,
an input/output process is carried out to treat semiconductor auxiliary
storage 9 as a hard disk (step 204).
FIG. 9 is a flow chart of steps used in determining the storage capacity by
using the memory type for semiconductor auxiliary storage 9 which is
determined in step 202 of FIG. 8. As a preliminary steps to determining
the memory type, the flags for indicating the memory type, i.e., a ROM
flag and a RAM flag are each cleared to zero (step 301 and 302). Then, a
determination or examination is made as to whether or not the RAM contents
have been loaded into semiconductor auxiliary storage 9 (step 303). If the
RAM has been loaded, the RAM capacity is determined by an erase/write
capacity register (step 304), as described in connection with FIG. 3B, and
the RAM load flag is also set (step 305). The RAM capacity can be
calculated by multiplying the contents of the erase/write capacity
register by 64 KB. Then, the memory type register is again examined to
determine whether the ROM contents have been loaded into semiconductor
auxiliary storage 9 (step 306). If the ROM has been loaded, the capacity
of a ROM is determined by the non erase/write capacity register (step
307), as described in connection with FIG. 3C, and a ROM load flag is also
set (step 308). In this manner, the capacity for each memory type used in
semiconductor auxiliary storage 9 can be ascertained.
When memory circuit 21 of semiconductor auxiliary storage 9 is configured
as ROM only memory, it is not possibl | | |
