CDC Finch Alternatives Today [WAS:RE: Evotek Winchester Harddisk]

[Oliver Lehmann]

Hi Tony,

they definity mean not SMD with "CDC" as for SMD a complete different
controller exists for the system which explicitly is for SMD drives
only.

Oliver

Tom Gardner <t.gardner at computer.org> wrote:

> The manual u cited states, "The disk controller can control either a  
> CDC or Finch drives. All drives attached to any controller must be  
> of one type."  I'm not sure what they mean by "CDC" but if u are  
> lucky it might mean "SMD."
>
> According to the 1983 Disk/Trend Finch interfaces were available on  
> the Wren 9415-32 (Finch and ST506) and the Wren 94153 (Finch only).   
> So u might look for a 94153 or a Finch variant of the 9415-32.
>
> The Finch spec data interface specs include 13440 unformatted bytes  
> per revolution using an 806 KB/sec  data rate, which are the very  
> old at that time 3330 industry standards.  There are very few small  
> drives that use this standard, not even the 94153 (10,080 @ 605  
> KB/sec) so what happens with the drive at a different frequency and  
> the controller with a possibly a different number of raw bytes per  
> track is unpredictable.   Note that 10080 x 806/605 is close enough  
> to 13440 so any 10,080 @ 605 KB/sec drive might be made to work if  
> the recording channel has margin at the higher frequency;  
> unfortunately there are not very many.
>
> A bigger problem might be the command and control interface of the  
> Finch - it is not like the ST506/412.  Off the top of my head it  
> looks like a variant on SMD.  BTW SMD data specs are exactly  
> 1.5x3330, that is 20,160 bytes @ 1.209 MB/sec so a small SMD might  
> work if the recoding channel can deal with the lower data rate,  
> perhaps the 8715 FSD.  You might want to compare pin by pin SMD to  
> Finch to see if this is even possible.   There were some small SMDs,  
> e.g. Micropolis 1403, Priam 804 but most were 14-inch.
>
> Perhaps there is a CDC SMD expert in this group that can help
>
> Tom
>
>
>
> -----Original Message-----
> From: Oliver Lehmann [mailto:lehmann at ans-netz.de]
> Sent: Monday, December 07, 2015 11:39 AM
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: Evotek Winchester Harddisk
>
>
> Tom Gardner <t.gardner at computer.org> wrote:
>
>> Sorry If I didn't make myself clear, I am suggesting one never acquire
>> an Evotek drive today other than perhaps as an historical curiosity.
>>
>>
>>
>> The Finch was a short lived 8-inch HDD that went up to 42 MB
>> unformatted BUT according to Disk/Trend It did not use an ST506
>> interface but instead came with this  variety of interfaces: Finch,
>> LDI, SMD or SA1000!  So your problem is likely to be finding a drive
>> that matches the interface of yr controller card.   Some possibilities
>>
>>           Finch interface was available on certain CDC Wren 5 -inch
>> models, e.g. 9415
>>
>
>  From what I understood in the Zilog System 8000 manuals, it is the  
> Finch interface.
>
> http://bitsavers.informatik.uni-stuttgart.de/pdf/zilog/s8000/03-3237-04_hwRef_Dec82.pdf
>
> Page 33 - Drive Performance Characterstics Page 47 - Pinout of the  
> WDC-Controller Disk Connector Page 65-69 - Describing Driver  
> Configurations
>
>
> Here are pictures of harddisks used in the System 8000:
>
> http://pics.pofo.de/gallery3/index.php/S8000/Harddisk
>
>
> And this is the so called "FINCH Adapter Board" used in the S8000:
>
> http://pics.pofo.de/gallery3/index.php/S8000/S8000_boards/FINCH-Adapter-Board