connects to: Other

The DMAC and SDMAC are the C= custom chips that front the WD33C93A SCSI controller IC, and perform DMA transfer functions for that SCSI interface chip.  It actually presents an 8-bit PC-XT-like interface to a common PC chip like the WD33C93A, and provides custom logic glue and busmaster functions over the Amiga expansion buses.

On the A2091/A590 SCSI controlers, that bus is the 24-bit Zorro II expansion bus protocol of the original 68000-based Amiga machines.  DMAC-01 and DMAC-02 are applicable parts to these boards.  DMAC-01 has been seen mostly on early A590 products.  The DMAC-02 may be required for some 3rd party enhancements. 

In the A3000, the SDMAC can access the larger address space of the Zorro III expansion space.  

SDMAC-02 is intended for use with Ramsey-04.  DMAC-04 is intended for use with Ramsey-07. They address issues that require each other.  As per Dave Haynie (designer), "You can't mix them up".

The A4000T uses the NCR 53C710 3rd generation SCSI and DMA Controller, and is not a related chip to the DMAC/SDMAC.


Chip Name Part Number Used In
DMAC 390563-01 A590, A2091
DMAC 390563-02 A590, A2091
81-Super DMAC 390537-02 A3000D/T
81-Super DMAC 390537-04 A3000T
Page contributors: Robert Miranda (GVP Tech Support)
Updated: 1/25/2020 . Added: 12/23/2004