Speed measuring  and some results, programs

  By hard disks we are mostly interested for transfer speed (in KB/sec) and access speed (in milliSec, ms) .
I made couple simple program for it. Both programs measure access time by measuring average time of reading 1 sector at once by random postitions on whole disk or partition. It gives more usable result than measuring access time of some track on drive, what  is shorter, but in reality we must wait for accessing required sector on track too.

Download testing programs

It is with HDDAST4.TOS - it measures speed with direct access to hardware (DMA, IDE port). May test speed of installed driver - keys D and T (only for partition C ) . If machine has blitter may execute tests B and H - they will give better speed than C test. My later drivers use blitter if can in Hog mode, so may expect  very good speeds.

Tests are made with Sandisk 2GB Compact Flash card. Therefore very good random access time under 1ms.
Relatively low transfer rate of 718 KB/sec with installed driver is result of required byte-swap, since DOS partitioned disk was measured. (Without blitter it would be some 350 KB/sec).

Same program, disk is SCSI Quantum Viking. Of course it is with modified Mega STE's ACSI-SCSI adapter, otherwise we would be limited on 1GB. As I see, Quantum SCSI drives are fastest with Atari STE (it's DMA chip). Speed of 1243 KB/sec is very close to theoretical max. speed of 1.25 MB/sec on ACSI port. Other brands as IBM and Fujitsu performed me not more than 1110 KB/sec.
Drive is connected to adapter with self made 50pin-68pin (UW) cable.. With 'regular' cable converter it worked slower.

 In 1991 it was much slower and smaller....

Another program HDSWS.TOS measures only speed of installed drivers, but for all installed partitions. Access/read time is measured inside selected partition only, and therefore is better. Very high speed is result of twisted IDE cable and blitter, together with fast drive.

     Note: KB by testing programs here is 1024 bytes. MB (for capacity) is 1048576 bytes. 1GB is 1073741824 bytes. As we may see, difference between using 1000 and 1024 base increases by using large units - from 2.4% by KB to 7.4% by GB. Manufacturers use 1000 base to get bigger numbers of GBs - 160 GB WD drive has actually 149 GB of 'binary' gigabytes.

P. Putnik,  October 2007.

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