12 Aug
2019
12 Aug
'19
11:35 p.m.
On 8/12/19 8:16 AM, Nigel Johnson via cctalk wrote:
Another consideration with the TC02 is the small
buffer. I don't know
what tape speed your drive runs at, but we lost a lot of sales to Dilog
because of buffer overflow on some of the faster CDC dirves.? When we
came out with the TC03, it had a larger buffer to handle this.
The Qualstar drive is a *slow* drive. 50 ips in 1600 PE mode and a
whopping 12.5 IPS in 6250 GCR mode. Transfer rate in either is about
80KB/sec. Qualstar doesn't have a mechanical buffer (spring arms or
vacuum column) like most drives; it's all handled by the reel servos.
It's wonder that it works at all. I doubt that it will overwhelm a
PDP11. It probably doesn't overwhelm an IBM PC XT. The SCSI version
of the drive does have a 256KB buffer, but I'm uncertain what the Pertec
interface model has.
--Chuck