✓ VERIFIED

Commodore 128

C128 · 1985–1989 · desktop

Specifications

Cpu: MOS Technology 8502, 2 MHz (falls back to 1 MHz in C64 mode); plus a Zilog Z80A, 4 MHz, dedicated to CP/M mode
Ram: max: 128 KB directly addressable via bank switching; up to 512 KB with a Commodore REU (1700/1750/1764) plugged into the expansion port · base: 128 KB
Ports: Expansion/cartridge port · Serial IEC bus (disk drive, printer) · 2x joystick/control ports · Cassette port · RF and composite video (40-column, VIC-IIe) · RGBI monitor port (80-column, 8563 VDC) · User port (RS-232 with adapter)
Display: MOS VIC-IIe for 40-column, C64-compatible graphics (320x200 in 16 colors) over RF/composite; separate MOS 8563 VDC chip drives an 80-column mode (640x200 monochrome or 80x25 text) over its own RGBI monitor port
Storage: base: Commodore Datasette cassette recorder (no internal storage) · options: Commodore 1571 5.25" floppy drive (double-sided, 340 KB, serial IEC bus, also readable by CP/M mode) · Commodore 1581 3.5" floppy drive (800 KB, serial IEC bus)
Os Support: latest: Same ROM-resident BASIC 7.0 / CP/M 3.0 across the run; GEOS 128 available as a third-party GUI for C128 mode · shipped: Commodore BASIC 7.0 with three switchable modes: native C128 mode, full C64 mode (hardware-compatible), and CP/M 3.0 (via the onboard Z80)
Release Price: $299

Variants

Models

Commodore 128D1985 desktop-case variant with a built-in 1571 floppy drive and detachable keyboard, sold mainly in Europe.

Commodore 128DCRLater revision of the 128D with a redesigned mainboard and cost-reduced components; same specs.

Upgrade paths

RAM

512 KB via a Commodore RAM Expansion Unit (REU) plugged into the expansion port · Same DMA-based REU scheme as the C64: useful in native C128 mode with REU-aware software, of limited use in CP/M mode.

~$150-$200 for a 1750 REU at the time

MODERATE

storage

Commodore 1581 3.5" drive (800 KB per disk) or a 1571 for double-sided 5.25" disks readable in both C128 and CP/M mode · The 1571 is effectively required for full CP/M compatibility since it reads the double-sided format CP/M 3.0 expects.

~$250-$300 for a 1571 or 1581 at the time

EASY

display

8563 VDC video RAM from 16 KB to 64 KB for smoother 80-column scrolling and software fonts · Requires desoldering or socketing the onboard 4164 DRAMs and swapping in higher-density parts; a common hobbyist mod today, not something Commodore offered as a kit.

~$20-$40 in period RAM chips

HARD

CPU

Locked at 8502 (2 MHz) and Z80A (4 MHz) as shipped · Both CPUs are soldered to the mainboard; no official or common aftermarket speed-up path, unlike some C64 accelerator cartridges.

n/a

LOCKED