DTC 7280 16-Bit MFM RLL FDD HDD ISA Controller Card 1:1 Interleave VLSI

DTC 7280 16-Bit MFM RLL FDD HDD ISA Controller Card 1:1 Interleave VLSI

The DTC 7280 is a 16-bit ISA combo controller card that manages both MFM/RLL hard disk drives and floppy disk drives from a single expansion slot. It supports zero wait states at bus speeds up to 16 MHz and a 1:1 interleave ratio, which was the highest-performing interleave available for MFM drives and eliminated the rotational latency penalty that plagued slower controllers of the era.

Specifications & What's Included

• Model: DTC 7280
• Bus interface: 16-bit ISA (AT)
• Drive interface: MFM and RLL hard disk drives + floppy disk drives (combo)
• Interleave: 1:1
• Maximum bus speed: 16 MHz
• Wait states: Zero
• Main controller chip: VLSI VC2916-0001 (DTC 337-3, marking 00-08079-3)
• Floppy disk controller chip: Zilog Z0765A08PSC (FDC, date code 8951)
• Secondary HDD controller chip: DTC-332A (00-08075)
• Additional logic: 74LS132N, 74LS245N and other TTL ICs
• Form factor: Half-length ISA expansion card with bracket
• Card only — no cables included

Applications

The DTC 7280 was designed for IBM PC/AT-class systems and compatibles running 16-bit ISA buses — the dominant PC platform of the mid-to-late 1980s. MFM (Modified Frequency Modulation) and RLL (Run-Length Limited) encoding were the standard hard drive interface technologies before IDE/ATA took over in the early 1990s. A dedicated combo controller like the 7280 allowed builders and upgraders to connect both their MFM or RLL hard drive and a floppy drive through a single card, freeing up a slot in machines where expansion room was tight. The 1:1 interleave support was a meaningful performance feature: lower-end controllers of the period used 2:1 or 3:1 interleave, requiring the disk to make multiple rotations per track read; a 1:1 controller could read consecutive sectors in a single rotation. Cards like the DTC 7280 are today sought by vintage PC restorers and collectors maintaining XT/AT-era machines, and by hobbyists building period-correct systems around MFM drives. Compatible with IBM PC/AT and the broad range of 16-bit ISA clone systems from that generation.