{"id":6,"date":"2011-01-26T14:11:07","date_gmt":"2011-01-26T14:11:07","guid":{"rendered":"http:\/\/www.binarydevotion.com\/?p=6"},"modified":"2011-02-08T12:52:10","modified_gmt":"2011-02-08T12:52:10","slug":"archaeology-mfm-st-506-interface-reference","status":"publish","type":"post","link":"https:\/\/www.binarydevotion.com\/?p=6","title":{"rendered":"Archaeology: MFM \/ ST-506 Interface Reference"},"content":{"rendered":"

\"\"<\/a>Back in 1986, hard drives were a luxury and a damned expensive one at that.\u00c2\u00a0 The drive units themselves were large in volume and small in capacity, and quite astonishingly and unashamedly fiddly to set up. They were not mainstream, and sometimes it’s easy to forget how far we’ve come in quite a short period of time: MicroSD cards hold thousands of times more data than these things, and if the flux density achieved on the latest 2.5″ drives was translated to 5.25″ drive, well, it’d be a lot of storage.<\/p>\n

Part of the reason for this trickiness of setting up is the fact that the drives are dumb: rather than take a command to read or write a sector, they take commands to move heads, select platters and read or write data to an area of the track, and return the raw magnetic flux changes read off the disk directly to the controller card, which then has to make sense of it all. New drives return usable data, these things tell the controller the values of the magnetic flux strength and leave it up to them to work out. This is why newer drives are called IDE devices – intelligent drive electronics – the interpretation is built in.<\/p>\n

The pioneers here were Shugart Associates, later to become Seagate. The ST-506 was a 5MB full height drive that gave birth to a briefly lasting interface standard that was adopted by others such as Maxtor and Connor, to name but two.
\n
\nThe ST-506 interface relies on 2 cables: one 34-way control cable telling the drive electronics where to move to and what to do, and one 20-way data cable whose function is obvious given its name.\u00c2\u00a0 Drives typically\"\"<\/a> use an IDC edge connector, controllers typically IDC pin connectors.\u00c2\u00a0 A 5.25″ floppy cable will work as a controller cable as long as Pin1 is in the right place and the cable has no twist!\u00c2\u00a0 I dismantled a floppy cable to add the connector to another cable, making a 2 drive control cable – ensure Pin 1 is connected correctly as if you fit the connector upside down it won’t be…<\/p>\n

Up to 4 drives can be connected dependent upon the controller, cabling and power supply.\u00c2\u00a0 The control cable simply connects all drives in parallel, and a separate data cable is needed for each drive to the controller card.<\/p>\n

There is a termination resistor on each drive, too.\u00c2\u00a0 This must only be present on the last drive on the controller cable.\u00c2\u00a0 Each drive has an ID, assigned by a jumper, from 1 to 4.\u00c2\u00a0 Unless you want to corrupt disks, ensure each is assigned a unique ID!<\/p>\n

You can have drive ID 2 as the first drive in the chain without termination, so if you are adding a drive to a system you can leave the original drive alone if it’s going to be on the end of a chain: remove the terminator from the new drive, and change the ID.
\n
\nConnect it up, power it up, and hope that your drive likes your controller card.\u00c2\u00a0 I use Seagate drives (st-225 and -st251) on an Omti 5520 controller, which seems to work well.\u00c2\u00a0 If all is good, prepare it for use.\u00c2\u00a0 Bear in mind you will need to use a controller-specific utility to low level format your drive…<\/p>\n

\"\"<\/a>You will probably find that the drive is noisy: this is really to be expected from a 20 year old piece of delicate electronic equipment. Feel the weight of the thing and, if you’re brave, hold it whilst it powers up: the gyroscopic effect from those heavy platters is really quite marked! You will hear a knocking from the drive as it powers up, and the 225 will knock quietly when it powers down due to the neat autopark feature of this drive that turns the motor into a generator to power the stepper motor to move heads to the parking zone.<\/p>\n

Resources: ST-225 manual<\/a>, ST-251<\/a> manual,ST506 OEM Manual(Apr81)<\/a>,\u00c2\u00a0ST412 OEM manual(Apr82)<\/a><\/p>\n

My MFM drives live on a Spirit HDA-506 interface<\/a> on an Amiga 1000<\/a>.\u00c2\u00a0 See the Review<\/a> for more information!<\/p>\n","protected":false},"excerpt":{"rendered":"

The ST-506 from Shugart Associates, later Seagate, was the first de facto standard for hard drive interfacing. It was crude by modern standards, but showed that manufacturers could choose to ride on the wave of standard interfaces…<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,11],"tags":[30,29,19,28,26,27,25],"class_list":["post-6","post","type-post","status-publish","format-standard","hentry","category-binary-history","category-howtos","tag-30","tag-mfm","tag-omti","tag-st-251","tag-st-506","tag-st251","tag-st506"],"_links":{"self":[{"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=\/wp\/v2\/posts\/6","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6"}],"version-history":[{"count":0,"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=\/wp\/v2\/posts\/6\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.binarydevotion.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}