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blog:pc98_hdd [2019/07/29 10:21] – [Tools and Utilities] johnblog:pc98_hdd [2020/03/28 12:11] (current) – john
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 PC-98 A-Mate series (Ae, Ap, An) all have a limited BIOS which supports IDE drives up to 540MB, some later machines support up to 4.3GB. SCSI controllers and disks can go bigger, up to 30GB-ish in some cases. PC-98 A-Mate series (Ae, Ap, An) all have a limited BIOS which supports IDE drives up to 540MB, some later machines support up to 4.3GB. SCSI controllers and disks can go bigger, up to 30GB-ish in some cases.
  
-However, support for anything bigger is just not possible on the stock system, such as [[https://targetearth.dyndns.org/vgdb/system/86|my PC-9821AN]]. Fortunately someone has developed a custom ROM overlay that replaces the standard BIOS routines that interface with the IDE drive to support up to 120GB (the limit of LBA28 or CHS addressing).+However, support for anything bigger is just not possible on the stock system, such as [[https://www.target-earth.net/vgdb/system/86|my PC-9821AN]]. Fortunately someone has developed a custom ROM overlay that replaces the standard BIOS routines that interface with the IDE drive to support up to 120GB (the limit of LBA28 or CHS addressing).
  
 It is technically possible to write this ROM to an unused card on the PC-98 C-Bus and have it initialised at boot time. The most common method would be something like a SCSI card, where the SCSI functions are not needed. It is technically possible to write this ROM to an unused card on the PC-98 C-Bus and have it initialised at boot time. The most common method would be something like a SCSI card, where the SCSI functions are not needed.
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 ---- ----
  
-==== Generating a custom ROM image ====+===== Generating a custom ROM image =====
 Install DOS to a supported hard drive, or make a DOS boot floppy and then extract the contents of [[http://hp.vector.co.jp/authors/VA012947/software/exide486.lzh|exid486.lzh]] to it.  Install DOS to a supported hard drive, or make a DOS boot floppy and then extract the contents of [[http://hp.vector.co.jp/authors/VA012947/software/exide486.lzh|exid486.lzh]] to it. 
  
 Boot the PC-9821Ap/As/An and run <code>exide486.com</code> and you should get a screen as follows: Boot the PC-9821Ap/As/An and run <code>exide486.com</code> and you should get a screen as follows:
  
-{{:blog:setexide486.gif?640|}}+{{:blog:setexide486.gif?400|}}
  
 Select which mode you want the ROM to run in (consult the [[http://hp.vector.co.jp/authors/VA012947/exiderom/exide486.html|table]]). The only option if you want to use the full capacity of a drive up to 120GB is **option 1** (how to partition and use that capacity is another exercise for later). Select which mode you want the ROM to run in (consult the [[http://hp.vector.co.jp/authors/VA012947/exiderom/exide486.html|table]]). The only option if you want to use the full capacity of a drive up to 120GB is **option 1** (how to partition and use that capacity is another exercise for later).
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   * EXIDE486.R01 - half of the 4KB image, for writing to the high bank of a dual EPROM board   * EXIDE486.R01 - half of the 4KB image, for writing to the high bank of a dual EPROM board
  
-==== Selecting a host card for the ROM ====+===== Selecting a host card for the ROM =====
  
 In my case I am testing the replacement IDE BIOS ROM on the following SCSI boards (the fact that they're SCSI doesn't matter - it just needs to a board that maps its BIOS into a standard ROM slot in memory; in fact a network card could work too): In my case I am testing the replacement IDE BIOS ROM on the following SCSI boards (the fact that they're SCSI doesn't matter - it just needs to a board that maps its BIOS into a standard ROM slot in memory; in fact a network card could work too):
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 ---- ----
  
-==== Tools and Utilities ====+===== Tools and Utilities =====
  
 The native utilities in PC-98 MS-DOS 6.2 or lower won't work with large drives; they may be okay with drives appropriate to the original BIOS capacities (512MB, 4GB, 8GB, etc) but they simply don't work with anything bigger. The native utilities in PC-98 MS-DOS 6.2 or lower won't work with large drives; they may be okay with drives appropriate to the original BIOS capacities (512MB, 4GB, 8GB, etc) but they simply don't work with anything bigger.
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 That's saying something about not being able to write the boot sector or something along those lines... it's the same regardless of disk. Also notice that it picks up the incorrect size of the partition, in the above image it should be showing a entire-drive partition from a 60GB disk... but it doesn't. That's saying something about not being able to write the boot sector or something along those lines... it's the same regardless of disk. Also notice that it picks up the incorrect size of the partition, in the above image it should be showing a entire-drive partition from a 60GB disk... but it doesn't.
  
-What you actually need to use is a tool called FORMATX which cannot be found on the web any more but can still be found via archive.org, at the links below or, alternatively, download a local copy from here: [[https://targetearth.dyndns.org/static/VGDB-images/pc98/fmtx128.lzh|fmtx128.lzh]]+What you actually need to use is a tool called FORMATX which cannot be found on the web any more but can still be found via archive.org, at the links below or, alternatively, download a local copy from here: [[https://www.target-earth.net/static/VGDB-images/pc98/fmtx128.lzh|fmtx128.lzh]]
  
 [[https://web.archive.org/web/20150303004824/http://hp.vector.co.jp/authors/VA012947/soft_disk.html|Archive.org copy of the HD disk software page]] - with links to other tools (for reference, the current page is [[http://hp.vector.co.jp/authors/VA012947/soft_disk.html|here]] and has no reference to FORMATX any more). [[https://web.archive.org/web/20150303004824/http://hp.vector.co.jp/authors/VA012947/soft_disk.html|Archive.org copy of the HD disk software page]] - with links to other tools (for reference, the current page is [[http://hp.vector.co.jp/authors/VA012947/soft_disk.html|here]] and has no reference to FORMATX any more).
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 And this is how FORMATX works: And this is how FORMATX works:
  
-{{:blog:img_20190728_221814.jpg?200|}}+{{:blog:img_20190728_221814.jpg?300|}}
  
 Run the tool and it scans for available devices - select the one you want to format - just a single IDE device in the example above. Run the tool and it scans for available devices - select the one you want to format - just a single IDE device in the example above.
  
-{{:blog:img_20190728_221814.jpg?200|}}+{{:blog:img_20190728_221814.jpg?300|}}
  
 Select the device and choose the partition you want to format - just a single partition in the example above. Select the device and choose the partition you want to format - just a single partition in the example above.
  
-{{:blog:img_20190728_221838.jpg?200|}}+{{:blog:img_20190728_221838.jpg?300|}}
  
-The formatting begins and you can see (blocks/sectors/megabytes?) being initialised. You then get a little synthesised speach fanfare when it finishes!+If you have selected a partition that can support multiple cluster sizes, then a menu is shown where you can select the size - anything over 60GB is forced to use 32KB clusters of course, so goes the downside of using huge FAT32 filesystems: 
 + 
 +{{:blog:img_0267.jpg?300|}} 
 + 
 +The formatting begins and you can see (blocks/sectors/megabytes?) being initialised. You then get a little synthesised speech fanfare when it finishes! 
 + 
 +Once the partition has been formatted, you can use the Windows 98 SE emergency boot disk to SYS the drive and make it bootable. 
 + 
 +You may want to create a DOS directory and copy over the contents of the Win 98 boot floppy, as well as extracting the EBD.CAB cab file which contains additional Win 98 SE DOS commands (edit, format, etc). 
 + 
 +=== IBM/PC Compatible Partitions === 
 + 
 +The PC-98 partition table is //not// compatible with Windows/Linux by default, even though the filesystems contained in those partitions //is//. However, once you've fully formatted the disk using FORMATX in PC-98 DOS, you then run a utility named CONV98AT.EXE to make a PC-compatible partition table: http://hp.vector.co.jp/authors/VA012947/hduty/conv98at.html 
 + 
 +{{:blog:img_0271.jpg?300|}} 
 + 
 +The image above shows the utility running on the fully partitioned and formatted 80GB IDE drive from the tests below. After this step, the above partition is dual-use and can be used fully in both PC-98 and in Windows and Linux on standard PC hardware.
  
 ---- ----
  
-==== Testing Large Drives ====+===== Testing Large Drives ===== 
 + 
 +  * Model: Hitachi 5K500,B-120 
 +  * Type: 2.5" SATA (using cheap SATA to IDE bridge board) 
 +  * Capacity: 120GB 
 +  * Result: **FAILURE** 
 + 
 +The drive is detected on the ROM screen. 
 +Disk initialisation fails, FDISK freezes during partitioning. Cannot be formatted. 
 + 
 +----
  
   * Model: Toshiba MK1255GSX   * Model: Toshiba MK1255GSX
   * Type: 2.5" SATA (using cheap SATA to IDE bridge board)   * Type: 2.5" SATA (using cheap SATA to IDE bridge board)
   * Capacity: 120GB   * Capacity: 120GB
 +  * Result: **FAILURE**
  
 The drive is detected on the ROM screen. The drive is detected on the ROM screen.
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   * Type: 2.5" SATA (using cheap SATA to IDE bridge board)   * Type: 2.5" SATA (using cheap SATA to IDE bridge board)
   * Capacity: 120GB   * Capacity: 120GB
 +  * Result: **FAILURE**
 +
  
 Drive is detected, but the ROM screen freezes and never attempts to boot from disk. Drive is detected, but the ROM screen freezes and never attempts to boot from disk.
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   * Type: 2.5" IDE   * Type: 2.5" IDE
   * Capacity: 60GB   * Capacity: 60GB
 +  * Result: **SUCCESS**
  
 The drive is detected on the ROM screen. The drive is detected on the ROM screen.
  
-Disk can be initialised. Initialised disk appears in fdisk and can be partitioned. New drive letter (c:) available within DOS, however, the Win 98 SE FORMAT tool errors out at 100% exclaiming that the boot sector cannot be written.+Disk can be initialised. Initialised disk appears in fdisk and can be partitioned. New drive letter (c:) available within DOS.  
 +The FORMATX tool runs correctly and successfully formats the entire partition (60GB). The newly formatted space appears and can be SYS-ed and booted from. 
 + 
 +{{:blog:img_0269.jpg?400|}}
  
 ---- ----
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   * Type: 2.5" IDE   * Type: 2.5" IDE
   * Capacity: 80GB   * Capacity: 80GB
 +  * Result: **SUCCESS**
  
 The drive is detected on the ROM screen. The drive is detected on the ROM screen.
  
-Disk can be initialised.+Disk can be initialised. Initialised disk appears in fdisk and can be partitioned. New drive letter (c:) available within DOS. The FORMATX tool runs correctly and successfully formats the entire partition (80GB). The newly formatted space appears and can be SYS-ed and booted from. 
 + 
 +Once processed with CONV98AT the drive also shows up normally within Linux and Windows on a PC. Excellent! 
 + 
 +{{:blog:img_20190728_222526.jpg?400|}}
  • blog/pc98_hdd.1564392090.txt.gz
  • Last modified: 2019/07/29 10:21
  • by john