Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!pasteur!ucbvax!DHDURZ1.BITNET!V61 From: V61@DHDURZ1.BITNET (Ronald Lamprecht) Newsgroups: comp.sys.atari.st Subject: low cost HARDDISK interface Message-ID: <8808270037.AA23210@ucbvax.Berkeley.EDU> Date: 27 Aug 88 02:35:01 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 65 Subject: low cost HARDDISK interface In his article (9 Aug 88 15:07:47 GMT) icc!jlong@blackbird.afit.af.mil (Jeffrey K. Long) asked: >Could someone please post more info on the article in the German magazine that >told how to hook up a standard XT drive and controller to the ST! Several >people in my user's group are very interested in this prospect. I understand > that a circuit board and some driver software are all that is needed. I also >heard that with some patches the system could now autoboot also. So what's the >catch other than the fact that you don't have access to your DMA port? >Is this thing slower than using a Berkley board and Adaptec controller? >What magazine did it appear in (Name and Issue) and would anyone who reads >German be willing to translate the article to English? Help!!!!! The low cost solution mentioned was published in the German magazine "c't" (Verlag Heinz Heise GmbH & CoKG, D-3000 Hannover, W-Germany) issue 2/88 p126ff . It uses an OMTI 55xx controller and a small interface build up of 5 `standard' 74xx ICs. This solution occupies the whole DMA port - so you have no further access to the DMA port. In issue 5/88 p122ff a ROM patch was published which allows an autoboot. Based on the idea of using an OMTI controller I developed another small interface (9 `standard' 74xx ICs) which does not block the DMA port but provides drivers for all important DMA port signals. It uses also the OMTI controller 55xx and I have tested it with two controllers each supporting an OMTI 5527a with 2 ST277R drives (240 MB in total !). But I haven't tested the controller with Atari or foreign DMA port devices - in fact I don't believe that it will work with the Atari laser printer (I have heard that many other DMA port devices have difficulties with this printer or the software). But I wanted to keep the port clean for further self build hardware extentions and not for obscure foreign products. The controller works with no problems since April 88 - the software (not identical to that published in c't) consists of a GEMDOS driver,formatter & utilities, an OS9 driver (real multitasking) & software to access GEMDOS partitions from OS9 and vice versa. 8 partitions per Harddisk, 2 drives per controller (up to 8 controllers,...) are supported. The speed is primarily limited by the operating system (even with Fatspeed) - data transfer rate with an OMTI 5527a : Interleave 1, 512 Bytes/sector, 26 sectors/track, 60 rpm = 800 kByte/s (There is no hardware to slow down the data transfer rate !). My favorite solution consits of an OMTI 5527a and 1 or 2 ST277R (each 65 MB), but I have also used an ST238R (32MB) and an ST251 (40 MB) with an OMTI 5520a. So the costs for a 60 MB harddisk are: selfbuild controller + cabels c 50 DM OMTI 5527a c 170 DM Seagate ST277R c 850 DM --------- c 1070 DM c $580 + Power supply If there exits an real interest (several requests) I would try to explain my own solution in detail and to post the sources (c200 k), but I won't translate the c't solution (I don't know whether they would agree,...) In a limited amount I would also be able to produce and send boards for about 20 DM + postage. If there is a real great request I will perhaps snake mail a copy of the layout (2 sided) to a few persons who oblige to distribute this copy to all persons interested in it in their region. Bitnet: V61@DHDURZ1 Ronald Lamprecht UUCP: ...!unido!DHDURZ1.bitnet!V61 Theoretische Physik ARPAnet: V61%DHDURZ1.BITNET@CUNYVM.CUNY.EDU (Heidelberg, West Germany)