Lo-tech ISA CompactFlash Adapter — XT-IDE Storage Solution
The Lo-tech ISA CompactFlash Adapter is an open-source 8-bit ISA card that enables modern CompactFlash storage on IBM PC XT, AT, and compatible systems. Paired with the XTIDE Universal BIOS, it provides silent, reliable mass storage for vintage computers using inexpensive CF cards. The design uses only five through-hole ICs, making it accessible for home assembly. Originally designed by James Pearce at Lo-tech, with hardware schematics and BIOS source code freely available.
- Bus Interface
- 8-bit ISA (fits any PC/XT/AT 8-bit slot)
- Storage Media
- CompactFlash Type I/II via 40-pin IDE header
- I/O Address Range
- 300h–31Fh (300h–30Fh active)
- ROM Address
- C800h (32 KB window, directly flashable in-system)
- Flash ROM
- SST39SF010A 128KB (32 KB used) — in-system programmable
- Compatible Flash ICs
- SST39SF010A, SST39SF020A, SST39SF040, AMIC A29010
- Supply Voltage
- 5V from ISA bus
- IC Count
- 5 through-hole DIP ICs (basic build)
- PCB
- 2-layer, ISA form factor, through-hole only
- BIOS
- XTIDE Universal BIOS — GPLv2, supports up to 4 IDE controllers
- Transfer Modes
- PIO-8 (standard), PIO-8 BIU Offload, PIO-16 BIU Offload
- Max Drive Capacity
- Unlimited with MS-DOS 7.x/FreeDOS; 8.4 GB limit on DOS 3–6
Coding the scene
Typical categories
Bullet: 4k / 64k intros (size-coding) Bullet: Trackmo / demo (multi-part) Bullet: Music disk Bullet: Graphics collection
Workflow
Bullet: Choose a target and constraints (speed, memory, chipset) Bullet: Build a minimal framework (sync, input, timing, loader) Bullet: Iterate effects + transitions Bullet: Profile early, optimise late, then profile again
Notes by platform
Bullet: Amiga: copper/blitter, C2P, AGA bandwidth, timing on real hardware Bullet: C64: cycle-exact raster timing, stable IRQ, sprite multiplexing Bullet: Atari ST: sync tricks, low-level video, DMA sound constraints Bullet: PC: DOS timing, VBL sync, fixed-point, software rendering, or modern GPU