NEC Retro:Determining PC-9800 computers

As a continously evolving platform, the PC-9800 series creates a number of documentation issues for NEC Retro.

Different publishers took different approaches to classifying their software, often making assumptions about the state of the market at the time of release. NEC supporting the platform for nearly twenty years, and its often confusing naming scheme means mistakes are often made, and as all PC-9800 series computers are expandable, it is fully possible to upgrade an older machine to the point where it matches newer machine specifications.

NEC Retro categorises software by the minimum required specifications; typically the earliest computer that can load and run the software as intended. We define computers by how they were originally sold (i.e. in an unexpanded state); if a piece of software can be successfully loaded and run (as expected) on an unexpanded machine, it is deemed as "made for" that machine.

Why not treat the PC-9800 series like IBM PC compatibles?

Perhaps the closest match to the PC-9800 range is that of the IBM PC, which after gaining traction in Western nations, would become the dominant computing format worldwide. The IBM PC was also a continously updating machine, however unlike the PC-9800 series, its creator, in this case IBM, did not fully control the market. "IBM PC compatibles" were made available from third-party manufacturers as early as 1982, who would take it upon themselves to offer computers with specifications different to IBM.

As such, it is unrealistic to categorise IBM PC games by defined sets of standards. Once a range of computers were made available, customers purchasing PC games would be expected to compare individual hardware requirements with their system, e.g. CPU, RAM, disk space, media type etc. The Retro family of wikis typically choose to make a distinction between older games designed for MS-DOS and those for Microsoft Windows operating systems, but the specifications problem continues to persist with PC games to this day

NEC, meanwhile, did release defined sets of standards for its PC-9800 series, and publishers usually targeted those standards. This means, while choosing to class every piece of software as "PC-9800 series compatible" is valid, there are thousands of games, and as most are incompatible with earlier devices, it makes sense to group games into sub-categories based on NEC's defined standards.

The PC-8800 series theoretically also has differing standards, however in this case is it much easier to follow as significant upgrades were rare.

Determining standards

A large percentage of PC-9800 series software will clearly state which computer it is targeting on its box, others will only give clues, some are deliberately vague and occasionally a box will be flat-out wrong. Tips for determining standards are as follows:

The name on the box/manuals/media

In most cases, PC-9800 series games will specify their target platform on either the box, physical media or any documentation that shipped with the product. We can safely assume "PC-9801 F" means the game is compatible with the PC-9801 F.

While theoretically software could target any machine, those most likely to be targeted are as follows:

• The original PC-9801 (which can be assumed for any software made before October 1983, as there were no other computers in the range).
• PC-9801 F
• PC-9801 M
• PC-9801 U
• PC-9801 VF (though this is rare)
• PC-9801 VM
• PC-9801 UV
• PC-9801 VX
• PC-9801 UX

This list is in date order, e.g. the PC-9801 M came before the PC-9801 VM, thus a game that lists both computers is classed as a PC-9801 M game.

Any numbers listed at the end of name (for example, "PC-9801 U2" or "PC-9801 VM2") can be safely ignored; NEC often sold variations of computers with differing disk or hard drive configurations which are determined with numbers, but the core technical feature set across these variations is usually the same.

In some cases, later hardware revisions were released with upgraded technical specifications. In the interests of simplicity, NEC Retro is ignoring the following machines:

• The PC-9801 F3 (1984-10), which has 256KB of RAM as rather than the 128KB of the F1 and F2.
• The PC-9801 VM21 (1986-11) and PC-9801 VM11 (1988-11), which have 640KB of RAM rather than the standard 384KB in other VM machines.
• The PC-9801 UV21 (1987-06) and PC-9801 UV11 (1988-03), which have 640KB of RAM rather than the standard 384KB in other UV machines.

Some publishers talk about "series". Typically this means:

• "F series": PC-9801 F
• "M series": PC-9801 M
• "U series": PC-9801 U
• "V series": The PC-9801 VF or the PC-9801 VM. Further checks may be required.

Specialised computers in the PC-9800 range, such as the high-end machines, laptops, notebooks and all-in-one devices such as the PC-9801 CV either did not receive games or are earlier desktop machines sold in different form factors, so can also be safely ignored.

If multiple formats are being listed, this rule may not be a sufficient way of determining the target platform, as the publisher is taking into account potential upgrades to a computer (which we do not).

The type of media

If the above test fails, the next plan is to check the type of media. No (unexpanded) PC-9800 series computer is compatible with every type of media games were sold as; if a game cannot be physically loaded into a computer, it is clearly not compatible.

NEC Retro only makes one exception to this rule; the original PC-9801. For a full year, it was impossible to buy a PC-9800 series computer that came with a means of interfacing with game media straight out of the box, so unless we were to disregard a more than a year's worth of software, the above rule cannot apply in this case. This is the only exception; in the eyes of NEC Retro, the PC-9801 E which also lacked these features, has no dedicated software library.

NEC Retro assumes PC-9800 series floppy disk drives came in pairs. While some games demand two disk drives, it was very much possible to buy computers with just one, thus the game is technically incompatible. However in all cases were a single drive was an option, the two drives were also an option (e.g. the PC-9801 VM0 (no drives) launched at the same time as the PC-9801 VM2 (two drives) - we class both as under the same PC-9801 VM format).

Similarly, later games, much like the IBM PC, need to be installed to a hard drive in order to function (i.e. they cannot be played straight off the disk). Not all PC-9800 computers shipped with a hard drive, but the option to do so was offered as early as 1984/1985.

Types of media

Compact cassette

Unlike the PC-8800 series, games sold on cassette are very rare and typically only existed within the first year (i.e. prior to the launch of the PC-9801 F). Unless the box says otherwise, we can assume that these are original PC-9801 games.

8-inch floppy disk

When the original PC-9801 computer was launched, the only floppy disk drives available were sold as part of the PC-9881 (or a PC-8881, which is also compatible), which utilises 8-inch floppy disks. This format was expensive and quickly abandoned after the launch of the PC-9801 F; unless the box says otherwise, games sold on this format are almost certainly original PC-9801 games.

While there are multiple types of 8-inch disk, at the time of the PC-9801's launch, most were (double sided) single density "2D" disks, and as the PC-9881 can read all 8-inch formats, all are treated the same.

5¼-inch floppy disk

Note that these disks were also marketed as "5-inch".

"Single density" (2D) and "Double density" (2DD) (640KB formatted)

The PC-9801 F in 1983 shipped with 5¼-inch 2DD drives, and was the only machine to do so until July 1985. Any games released on this format before this date are PC-9801 F games.

2DD drives can read 2D disks, and while it is not thought many (if any) games were released on the single density format, these too are classed as PC-9801 games before this date.

"High density" (2HD) (1MB formatted)

The PC-9801 M in 1984 shipped with 5¼-inch 2HD drives which can only read 2HD disks, meaning games released on this format before July 1985 are PC-9801 M games.

Dual-format 2DD and 2HD drives

The PC-9801 VM introduced dual-format 5¼-inch drives which can read both 2DD and 2HD disks; a feature that would be included for all 5¼-inch floppy drives from that point on. As such, "density" is no longer a factor for determining software released after July 1985.

3½-inch floppy disk

"Double density" (2DD) (640KB formatted)

The "slimline" PC-9801 U uses 3½-inch 2DD floppy disks, and was the only machine to do so until June 1986. Any games released on this format before this date are PC-9801 U games.

"High density" (2HD) (1MB formatted)

The PC-9801 UV uses 3½-inch 2HD floppy disks, and was the only machine to do so until October 1987. Any games released on this format before this date are PC-9801 UV games.

Compact disc

Compact discs were not included as standard until the PC-9801 BX4 in July 1995.

RAM requirements

If the above is not enough to determine the platform, RAM comes next. Every PC-9800 series machine comes equipped with at least 128KB of RAM.

• Games that require more than 128KB of RAM are incompatible with the original PC-9801, PC-9801 F (1 and 2) and PC-9801 U.

• Games that require more than 256KB of RAM are incompatible with the PC-9801 M and PC-9801 VF.

• Games that require more than 384KB of RAM are incompatible with the PC-9801 VM and PC-9801 UV.

• Games that require more than 640KB of RAM are incompatible with the PC-9801 VX and PC-9801 UX.

CPU

A game may specify a certain processor be available. It is unlikely, but not impossible, that the user has upgraded their processor rather than purchased a new system:

• If a V30 is specified, the game is incompatible with the original PC-9801, PC-9801 F and PC-9801 M.

• If a 286-class processor is specified, the game is incompatible with the PC-9801 U, PC-9801 VF, PC-9801 VM and PC-9801 UV.

• If a 386-class processor is specified, the game is incompatible with the PC-9801 UX and PC-9801 VX.

If all else fails

The only way to determine the format is all other checks have failed is to test on the actual hardware.

Table

Media	RAM	CPU	Computer
Compact cassette	128KB	8086	PC-9801
8-inch floppy disk	128KB	8086	PC-9801
5¼-inch 2DD floppy disk	128KB	8086-2	PC-9801 F
5¼-inch 2DD floppy disk	256KB	V30	PC-9801 VF
5¼-inch 2HD floppy disk	256KB	8086-2	PC-9801 M
5¼-inch 2DD or 2HD floppy disk	384KB	V30	PC-9801 VM
5¼-inch 2DD or 2HD floppy disk	640KB	80286	PC-9801 VX
3½-inch 2DD floppy disk	128KB	V30	PC-9801 U
3½-inch 2DD or 2HD floppy disk	384KB	V30	PC-9801 UV
3½-inch 2DD or 2HD floppy disk	640KB	80286	PC-9801 UX

Other issues

PC-9800 compatibles

By the early 1990s, Epson's PC-9800 compatible machines may also be specified. While these may provide clues, NEC Retro uses NEC's standards to define categories.

Windows PC games

Games designed for Microsoft Windows (of which versions were authored for the PC-9800 series) are classed as Windows PC games and are outside the scope of NEC Retro.