THE ADAPTEC  ACB-2070A
                       5 1/4" Winchester Disk Controller
              ==================================================

Overview:
A High Performance 5 1/4" & 3 1/2" Winchester Disk Controller for the IBM-PC
or XT and equivalent computers. It is fully hardware & software compatible
with the IBM XT hard disk controller.

The controller's most outstanding feature is it's use of RLL (Run Length
Limited) encoding to provide approximately 50% more hard disk capacity than
available with standard MFM encoding methods.  This is accomplished by
formatting the drive with 25 sectors per track versus the 17 sector per track
scheme used in MFM encoding. This controller will also efficiently utilize 3
to 1 interleaving of the disk as opposed to the 6 to 1 standard in most hard
disk controllers. This achieves the maximum rate of DMA transfers thet the
IBM-PC bus can accept. For even more flexibility, the interleave can be user
varied from 3 to 9.

An on-board primary (low-level) format utility is included in the card's ROM.
no additional utilities are needed except the standard DOS FDISK & FORMAT.

The controller will support any two type ST-506 Winchester Drives, they need
not be the same capacity or manufacturer.  Wedge servo type drives such as
Syquest and Microscience International are also supported without the need to
order special controller firmware.

Below is a list of Drives currently known to function correctly with the
Adpatec ACB-2070A.

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       According to Adaptec, the ACB-2070A has been successfully tested
                      by them with the following drives:

Drive Model			Capacity (RLL Format)

  Seagate		ST-238		31MB

  Rodime		RO352		15MB
         	RO202E 		31MB
        		RO203E		47MB
        		RO204E		63MB

 Tandon		TM502		15.6MB
       		TM755		62MB

 MicroScience	HH-325		31MB

 Miniscribe	3425 		31MB

NEC		3126		31MB
   		5126		31MB

Mitsubishi	MR522		31MB

Priam (Vertex)	V150		62MB
             		V170		90MB

Syquest		SQ319		15MB
       		SQ357		45MB

Tulin		TL226		31MB
       TL326		31MB
     		TL240		48MB
     		TL340		48MB

Toshiba		MK56FA		105MB

MicroStorage	MS212	 	15MB

Lapine		Titan		31MB

Okidata		OD526 		31MB
       		OD540		48MB

Bull		D530		38MB
    		D550		63.2MB
    		D570		88.4MB
    		D585		104.5MB


The Adaptec controller board has been successfully tested in
the following personal computers:

IBM-PC
IBM-XT
Compaq Portable
Compaq Deskpro
Compaq 286 Portable (Note 1)
Compaq 286 Deskpro (Note 1)
AT&T 6300 (Note 2)
Leading Edge (Note 1)
Sanyo
PC's Ltd. Turbo PC (both 4.77 & 7mhz)
Eagle

Notes:

1. ACB-2070A requires product P/N 401400 Revision C or later.

2. Requires AT&T motherboard ROMS version 1.21 or later.

This information is furnished per Adaptec letter dated 4/18/86

PLEASE NOTE!  THE ADAPTEC ACB-2070A WILL NOT WORK IN AN IBM-AT OR 80286 BASED
              MACHINE.  It also, at this time, suffers from poor compatibility
              with PC type machines using a "Turbo" board with the 80286 CPU.
              It is believed that Adaptec will correct the problem with the
              "Turbo" boards, but at this time, nothing is for sure.
believed that Adaptec will correct the problem with the
              "Turbo" boards,