24 Sep
2021
24 Sep
'21
1:19 p.m.
On Tue, Sep 21, 2021 at 12:15:12PM -0400, Paul Koning wrote:
The MFM emulator can't transfer data faster than the 5 Mbit/second,
625k Byte/sec of the ST-506 standard.
Seek time isn't zero due to overhead in moving the data in the Beaglebone
to where the PRU processors can access it. Think its around 0.6ms/head. An
entire cylinder is transfered on each seek. Additional time if cylinder
was written to. Each track written needs to be moved also. Most ST-506
drives are slower. I'm faster than average seek for RD54 but it wins for
single track seek at 4ms with 15 heads.
On Sep 21,
2021, at 12:00 PM, Jonathan Stone via cctalk <cctalk at classiccmp.org> wrote:
The RD53s in both Microvax 2000s are dead. I'm reluctant to buy more 30+ year old
rotating media.
If I'm going to buy a disk emulator, I'd much prefer SCSI to MFM, for the obvious
performance reasons.
Emulators presumably act, performance wise, like SSDs. Given that, an MFM emulator will
significantly outperform a SCSI hard drive since it has no seek delays.
David Gesswein's MFM emulator works impressively well and is inexpensive, too.