Re: Read-speed of SCSI CD-rom players

[spec@vax2.concordia.ca (Mitchell Spector)]

In article CUTjefbla@bconnex.net (Jeff Blakeney) writes...

>On 28 Dec 1998 09:42:45 GMT, buggie@ben16.unm.edu (stephen e buggie)
>wrote:
>
>>I've been shopping for a used low-cost SCSI external CD-rom player.  The
>>main variable
>>that affects price is speed: 1x, 2x, 6x, 32x etc.
>>
>>How important would this be for Apple IIgs or for Mac SE or Classic?  I'd
>>expect that the main use would be for reading in the software.  But why
>>would speed matter for that application?
>
>Well, keep in mind that a single speed CD-ROM drive has a max data
>transfer rate of 150 kB/s and that the fastest IIgs' SCSI cards that
>are currently available can only transfer data at a maximum of 1 - 3
>MB/s.

    Actually the maximum (peak) transfer rate of the Apple HS SCSI
and RamFAST SCSI is 1 MB/sec. In general use you will get no where
near that peak rate, probably half that or even less. This is when
talking about the Apple IIgs, the peak rate on a IIe starts off at
around 500k/sec and drops off significantly for general usage.

>This means that having anything faster than a 6x CD-ROM drive
>(900 kB/s) would be a bit of a waste.

    I still think anything more than a 4x drive is overkill on the
IIgs, especially when you consider peak and average transfer rates.
Simply because the SCSI card is capable of transferring data at up
to 1 megabyte per second, doesn't mean you'll be able to attain
that transfer rate.

>You will notice a huge difference between using a single speed and a
>six speed drive even on a IIgs.  This will mean much faster file
>transfers from the CD-ROM drive no matter what you happen to be doing
>with it now or in the future.

    In my opinion, 1x drives on a IIgs should be quite respectable,
with a 2x being more preferrable if you can get one. 3x, 4x and 6x
drives are nice if you can get them for around the same cost as a
slower drive, but would be more for gee-whiz value than practical
use.

>At present, unless my brother gives me his old single speed SCSI
>CD-ROM drive, I'll be shopping for a 4x or 6x drive but wouldn't turn
>down a 2x or 8x if the price were right.  :-)

    Heh, my brother has a mountain of dead or flakey CD-ROM drives,
although most are IDE (a 1x, a 16x, and three 2x's). One of them is
a NEC SCSI 2x drive, though it'd probably be cheaper to replace it
than repair. They're useful as fancy looking 5.25 bay port covers. :)

Mitchell Spector
spec@vax2.concordia.ca