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Article View: comp.sys.zenith.z100
Article #350

Hard Disk controllers for ANY S100 Computer

#350
From: Eric Liber
Date: Wed, 11 Nov 1987 15:37
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Hi, 
I have been away from usenet for a while and when i get back what do you
think?  a z100 news group!  will wonders never cease?  Anyway, i have a z100
(8mhz,768k,2 5.25" drives 18' drive 32meg hd [actually a 40 meg q540], printer
[rx80], plotter (rs 6 pen)). I am currently running dos 2.18 9i know i should
upgrade to 3.2(.3?) but i spent a lot of money on 2.1 and the pup and a like
to get my money's worth.  I also would like to get windows so i could 
experiment with windows apps and get a jump on some things i am going to
have to do at work ...but i digress. 
The main reason for this posting is to inquire if anybody is interested
in a home brew hard disk system design.  Here is what i have done:
I acquired a hd (originally a 5meg st506 then st412 then q540) and a 
xebec s1410 controller card.  I built my own sasi adapter card and wrote my
own diskdriver ffor msdos.  This whole thing has been incredibly cheap for
me because of some unbelievable deal, but even you can do it cheaply if 
yyou shop carefully.  There are a couple of limitations to tthe system:
1) you cannot boot directy from the hd.  I boot from a floppy and then 
   transfer to the hd for the autoexec.bat
2) it is not as fast as a heath controller since i do not do DMA.  The 
   interface is a parallel type and does byte programed transfers (read:
   gets a byte at a time).. still it is about as fast as the original pcxt
   hard disk (that is a 5mh z100 = 4.77 mh xt  at 8mhz it is a little faster)
   so it is not too bad.
3) you cannot have multiple partitions.  There is one 32 meg drive for msdos.
   This is largely a function of the driver and the way i address thhe disk in 
   the driver and could be fixed.. i simply do not need it.

The hardware requirements are (in general):
   1) a winchester disk with st506 type interface.
   2) a xebec s1410 or s1410a controller card (depending on the need for
      requirements for an "embeded servo type drive"
   3) a power supply capable of 5v at about 3amps and 12 v at 3 amps (depending
      on the winchester).. This could come from inside the h/z100 but i
      used an external supply.  
   4) a box to house  the drive controller and p.s.  - i tried to mount the
      damn thing inside the low profile 100 and couldn't do it without 
      giving up on 5.25 drive so it is mounted in a handmade plexiglas case.
   5) an s100 prototyping card (vector etc)
   6) 12 integrated circuits (all common) 
   7) miscellaneous connectors, cable and hardware.

All parts are common and available from mail order suppliers.  the s1410(a)
controller is available periodically from various suppliers (halted, computer
surplus, etc) which advertise in mags such as NUTs and VOLTS.
All of this will cost ??? well here is my best guess from current prices:

	drive  $150 (10 meg)
	s1410   100
	proto	 25
	ic's	 10
	misc     30
	power	 30

	total  $345
this of course depends upon your junk box and access to surplus.  (if you live
in the sunnyvale area you are in fat city).

If anyone is interested i would be willing to provide a package of info on
this system including driver listing (send me a disk and i will send you the
ssource and com files for a couple of popular drives).  I would ask tthat you
send me $10 to cover duplication and mailing costs (believe me i won't make 
any thing on it). 
If you are interested yoou could post to this news group or get to me via
mamail at pitt!darth or you can call be at 412-374-7774 (work) or 412-367-7308
(home) between 7:30 and 10pm weekdays and weekends by sheer luck.

This system has been use for a year and a half with NO PROBLEMS (astounding!)
and was a direct response to the ridiculous price heath wants for a hard disk
system.

eric
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From: liber@darth.UUCP (Eric Liber)
Newsgroups: comp.sys.zenith.z100
Subject: Hard Disk controllers for ANY S100 Computer
Message-ID: <310@darth.UUCP>
Date: Wed, 11-Nov-87 10:37:20 EST
Article-I.D.: darth.310
Posted: Wed Nov 11 10:37:20 1987
Date-Received: Sat, 14-Nov-87 02:36:48 EST
Organization: Darth Software, Allison Park, Pa.
Lines: 72