Date: Sun, 1 Jun 86 13:08:56 PDT From: Ya'akov_Miles To: info-ibmpc Subject: Adaptek turns 20 megs into 30 (SPELLING IS ADAPTEC) Having heard rumours of a miracle hard disk controller that changed 20 megabyte winchesters into 30 megabyte winchesters, I finally tracked down and bought an Adaptek ACB-2070A controller. This controller uses RLL (Run-length-limited) encoding, as opposed to MFM encoding which was employed by my old CMS controller My observations on the Adaptek ACB-2070A are as follows: (1) My Seagate ST-225 now has 32 megabytes of formatted capacity instead of 20 megabytes with the CMS controller. (2) My Seagate ST-225 now seems to load programs 1.5 times as fast Maybe it is bceause there are now 25 sectors/cylinder with RLL as opposed to 17 sectors/cylinder with MFM. (3) The Adaptek ACB-2070A controller handles up to two hard disks of different sizes. It allows the creation of multiple logical disks out of one physical disk (but only if you want to do it) (4) No special diskettes were necessary. The format program is resident in EPROM, and is conversational. Very thorough error checking (retries inhibited) is performed. My year-old Seagate had no errors, even though it had been operated sideways, etc. (5) The manual supplied with the Adaptek controller was excellent It was a big improvement over the inaccurate, incomplete, misleading document that CMS supplied on cheap newsprint... ******************************************************************************* THE FOLLOWING IS COURTESY OF BOB SCHNIEBOLK, CONSULTING TECHNOLOGIES' 301-840-0360 NOTE: THIS DATA AS FAR AS IT GOES IS SOMEWHAT MISLEADING. WARNING TO ALL, THE ST-225 IS AN OXIDE COATED DRIVE. SEAGATE SPECIFICALLY WARNS THAT IT NOT, NOT, NOT, NOT BE USED WITH THE 2070A CONTROLLER. FILE LOADING WILL BE APPROXIMATELY 1.5 TIMES AS FAST BECAUSE THE EQUIVALENT TRANSFER RATE WITH RLL-ENCODING IS 7.5MHZ AS OPPOSED TO THE MORE STANDARD 5MZ DMA RATE. ACTUALLY, THE INTERLEAVE IS SET SO THAT YOUR PC WILL NOT BE OVER- WHELMED WITH DATA. THE NEW CORE TEST WILL SHOW AN INCREASE IN YOUR DATA TRANSFER RATE. SUITABLE DRIVES FOR THE ADAPTEC CONTROLLER INCLUDE THE SEAGATE ST-238 WHICH IS THE SAME WHOLESALE PRICE AS AN ST-225, BUT SPECIFICALLY DESIGNED WITH PLATED PLATTERS, MOST CMI DRIVES, MINISCRIBE, AND TULIN. BY THE WAY MANY ADAPTEC'S ARE SHIPPED WITHOUT MANUALS. THE ENTRY POINT TO THE LOW LEVEL FORMAT ROM BIOS ROUTINES IS DEBUG G=C800:CCC DO NOT ACCEPT THE DEFAULT PARAMETERS AS THEY ARE FOR THE PRESET DRIVES SELECTED BY MEANS OF THE JUMPERS ON THE ADAPTEC. INSTEAD, ENTER NO, AND TELL IT YOUR DRIVE PARAMETERS (#HEADS,#CYLINDERS). USE A STEP RATE OF 3 AND AN INTERLEAVE OF 3. THE BAD TRACK TABLE FORMAT CAN BE EITHER RLL OR MFM, AND THE ORDER CYL-HEAD OR HEAD-CYL SHOULD BE THE SAME AS THE BAD TRACK PLATE ON YOUR DRIVE (IT'S NOT THE END OF THE WORLD IF YOU GET IT WRONG) REMEMBER THE DOS LIMIT IS 32 MEGABYTES (ACTUALLY ABOUT 33.45 MILLION BYTES). THEREFORE YOU MAY NEED TO MAKE TWO LOGICAL DRIVES IF YOUR NEW DRIVE IS BIGGER THAN 33 MEGS. YOU CAN CALCULATE THIS AS FOLLOWS: DRIVE SIZE=512*#OF CYLINDERS*#HEADS*25 NOW AS FAR AS THE NUMBER OF CYLINDERS, YOU MIGHT WANT TO ADD 10 TO THE SPEC ON YOUR DRIVE AND TRY THE FORMAT. IF IT DOESN'T VOMIT, YOU'VE JUST RECLAIMED THE SPARE TRACKS WHICH ARE ON MANY DRIVES AND USED FOR BAD TRACK ALLOCATION DURING MANUFACTURER'S TEST. THE ADAPTEC ACTUALLY FORMATS EACH TRACK INTO 26 SECTORS AND USES ONLY 25. IF IT ENCOUNTERS A BAD SECTOR, IT REFORMATS THE SAME TRACK AND TRIES TO USE THE 26TH SECTOR INSTEAD OF THE BAD SECTOR. IF THERE ARE STILL BAD SECTORS, THE TRACK IS ELIMINATED. (ANSWER WITH CR'S TO THE NAME OF THE BAD TRACK FILE -LAST TWO QUESTIONS IN FORMAT CYCLE). ANOTHER, AND FINAL NOTE. IF YOU START WITH 2 LARGE PHYSICAL DRIVES AND END UP WITH 4 OR MORE, FDISK (IBM VERSION) MAY NOT SEE THE LAST TWO DRIVES. IN ORDER TO USE FDISK, REMOVE YOUR C: DRIVE (DRIVE #1), REPLACE IT WITH DRIVE #2. RUN FDISK, AND FORMAT THE TWO LOGICAL DRIVES. THEN REMOVE THE DRIVE #2. PUT DRIVE #1 BACK IN. RUN FDISK ON THE C: AND D: DRIVES AND FORMAT THEM. THEN, PLUG DRIVE # 2 INTO THE D:DRIVE SLOT ON THJE CONTROLLER. REMEMBER TO ADD A LASTDRIVE COMMAND TO CONFIG SYS (DEFAULT IS ONLY 5 DRIVES INCLUDING FLOPPIES). EOF --------------------------------------------------------------RJS 06/16/86