I remember NetWare's IPX/SPX network stack used a similar async mechanism. The caller submits a buffer for read and continues to do whatever. When the network

I remember NetWare's IPX/SPX network stack used a similar async mechanism. The caller submits a buffer for read and continues to do whatever. When the network card receives the data, it puts them in the caller's buffer. The caller is notified via a callback when the data is ready. All these were fitted in a few K's of memory in a DOS TSR. All the DOS games at the time used IPX for network play for a reason. TCP was too "big" to fit in memory.