PCMCIA Expansion
2026-02-21
Overview
The SCM ISAC2PR10 (FCC ID: MBPSCM-SBI-C2P, also marketed as the SCM SwapBox SBI-C2P) is a 16-bit ISA card that adds two PCMCIA (PC Card) slots to desktop machines. Installing it in the Compaq Portable 486c opens up the wide ecosystem of 1990s PC Cards — network adapters, flash storage, modems, SCSI controllers, and more — all designed for laptops of the era.
Card Specifications
| Attribute | Details |
|---|---|
| Part Number | ISAC2PR10 |
| FCC ID | MBPSCM-SBI-C2P |
| Manufacturer | SCM Microsystems (Identive) |
| Controller chipset | Vadem VG-469 |
| Bus interface | 16-bit ISA |
| PCMCIA slots | 2× (dual) |
| Voltage | 3.3 V / 5 V per socket (independent) |
| IRQs | 10 ISA IRQs |
| Memory windows | 5 mappable per socket |
| I/O windows | 2 per socket |
| Intel compatibility | Register-compatible with Intel 82365SL |
| Plug and Play | ISA PnP v1.0a (with EEPROM support) |
| Hot-swap | Hot insertion/removal supported |
| OS support | DOS (CardSoft/CardWare), Windows 3.1, Windows 9x |
| PCMCIA standard | PCMCIA Release 2.x / PC Card Standard / ExCA |
16-Bit PCMCIA vs 32-Bit CardBus
This adapter uses the original PCMCIA Release 2.x standard with a 16-bit data bus (Intel 82365SL-compatible via the Vadem VG-469). This is the earlier ISA-based PCMCIA interface — not the 32-bit CardBus (PCMCIA 5.0) that became common in mid-to-late ’90s laptops. CardBus is PCI-based and supports up to 132 MB/s, while 16-bit PCMCIA tops out around 20 MB/s.
In practice, 16-bit PCMCIA is plenty for the peripherals used here — WiFi adapters, CF storage, network cards, and modems all work fine. The bandwidth limitation only matters for high-throughput 32-bit CardBus devices designed for later laptops. A 32-bit CardBus card physically cannot be inserted into a 16-bit slot due to a different keying notch.
Installation
Just install it into the ISA slot!
Driver Setup
DOS: Tricky because there were different releases supporting different hardware. Finally got this working: SystemSoft CardSoft Version 3.1 with hot swapping!
Windows 3.1: SystemSoft CardSoft v3.1 & CardView for Windows 3.1
Documentation in progress.