This article will go more in depth on the technical details and model/generation specific quirks across the PC-9800 lineup. Partial and complete incompatibles like the hi-reso machines and the early portables (PC-98HA, PC-98LT) will not be covered.

The specifications described below are available across every official PC-9800 and compatible clone system:

• Use of an x86 processor, with full backwards compatibility back to the Intel 8086.
• Startup in Real Mode, providing a 1MB address space split into segments on a 20-bit address bus.
• A full 16-bit data bus between the processor and add-in boards, inserted into the officially dubbed "C-Bus" expansion slots.
• A full 16-bit I/O port address range.
• At least one floppy drive interface.
• Two uPD7220 (Graphics Display Processor, or GDC) video controllers, one for text generation and another for bitmap drawing, chained in a master/slave configuration where text is overlaid on top of the bitmap, and each with their own VRAM pool.
• The text GDC has at least 8KB of RAM and the graphics GDC at least 96KB.
• A pair of high resolution and low resolution character sets compliant with the JIS X 0201 standard.
• The possibility of adding, if not already built-in, an additional character ROM to supplement the high resolution character set with a double-byte encoded Kanji glyph set.
• The following display modes: 640x200/2 colors/6 pages, 640x200/8 colors/2 pages, 640x400/2 colors/3 pages, 640x400/8 colors/1 page
• A horizontal scan rate (HSync) of 24kHz, and a vertical scan rate (VSync) of 56.6Hz.
• A built-in beeper speaker or a passthrough of it's signal to a dedicated sound board.

The 1st generation of systems spans a release period between late 1982 and mid 1985, consisting of the original PC-9801 and it's derivatives: PC-9801E, PC-9801F, PC-9801M.

The technical specifications are as follows:

Misc info:

• The 8253A PIT's 2nd counter is responsible for driving the DRAM refresh timings, unlike all later generations where it controls the beeper's playback frequency. As such, the frequency cannot be controlled.
• Due to the lack of 16 color graphics, 80186 instructions, and GRCG chipset out of the box, most games from 1985 onwards will not support these models
• Kanji support requires an additional C-Bus card with the appropriate character ROM

The 2nd generation of systems spans a release period between mid 1985 and early 1988, coexisting with the subsequent two generations. The lineup consists of the PC-9801VF, PC-9801VM, PC-9801UV and their revisions.

The technical specifications are as follows:

Misc info:

• The amount of color entries at once can be increased from 8 to 16 colors with the PC-9801-24 add-in board
• The baseline for a large percentage of games, even those that would only really run at full performance on a 286 or 386 based machine

The third generation of systems spans a release period between late 1986 and late 1990. It is made up of the PC-9801VX, PC-9801UX, PC-9801RX, PC-9801EX, PC-9801DX, and their revisions.

The technical specifications are as follows:

Misc info:

• This is the last time the graphics system would receive an upgrade, until the release of the 256-color PC-9821
• The original PC-9801-26 cannot be used with this or any later generation model, since the card doesn't have it's own clock crystal and relies on the computer to drive it's clock. The card will misbehave due to the faster CPU, so the improved PC-9801-26K must be used instead.

The fourth generation of systems marks the start of the 32-bit era and spans a release period between mid 1988 and mid 1992, though some would argue that extends to 1995. The models include the PC-9801RA, PC-9801RS, PC-9801ES, PC-9801DA, PC-9801DS, PC-9801CS, PC-9801FA, PC-9801FX, PC-9801FS, PC-9801US, and their derivatives. Some would also include the BA, BA2, BX, BX2, BS2, BA3 and BX3 from 1993-1995 but they're really just the budget alternative to the then new PC-9821 series, lacking 256 color modes.

The technical specifications are as follows:

Misc info:

• The last generation of 16-color models predating the PC-9821 series.
• The oldest generation that officially supports the PC-9801-86 sound board.
• With the ability to use Virtual 8086 Mode comes support for XMS and emulated EMS memory managers, making dedicated EMS cards redundant.
• Certain games like Stormy Space, Atomic Punker, and the Touhou Project series cannot run on machines older than these. Even though they are Real Mode games, they still make use of instructions first introduced on the 386.