Setup and Benchmarks of Several ESDI Hard Disks and Controller Cards

According to the manufacturer, the Micropolis 1538 is a 23 MHz disk drive, but with 41,664 unformatted bytes per track and 3,600rpm, the data transfer rate to storage media is only 20MHz. However, 894 megabytes capacity (with 70 sectors per track) was quite a few storage space in the year 1990, when a standard desktop disk drive had a capacity of 40 megabytes.

For whatever reason my 1538 supports 70 sectors per track max., while the spec sheet claims it supports 71 sectors per track. Anyway, here are the results.

Disk Drive	Controller Card	Access Time (milliseconds)	Sector Access Velocity (megabyte/s)	Burst Data Throughput (byte/s)	Sustained Data Throughput (byte/s)*	Storage Space (byte)	Translation Mode	Remarks
Micropolis 1538	Ultra 12C	29.043	5,126	1,653,952	710,667 (33,05%)	528,171,008	63-Sector-Translation
Micropolis 1538	Ultra 22CA	28.04	5,310	4,708,978	938,308 (43,63%)	528,171,008	63-Sector-Translation
Micropolis 1538	Ultra 22C	27.947	5,327	4,899,947	986,564 (45,88%)	528,171,008	63-Sector-Translation
Micropolis 1538	DTC 6295-24	26.589	5,594	2,420,206	988,933 (45,99%)	527,654,912	63-Sector-Translation
Micropolis 1538	DTC 6290-24	24.948	5,986	1,817,966	982,109 (45,67%)	528,171,008	63-Sector-Translation
Micropolis 1538	Ultra 12F24	23.488	6,339	1,559,067	1,296,160 (60,28%)	528,171,008	63-Sector-Translation
Micropolis 1538	ACB-2322D	23.255	6,396	1,519,512	1,101,471 (51,22%)	527,654,912	63-Sector-Translation
Micropolis 1538	WD1009V-SE2	23.073	6,440	1,638,226	741,203 (34,47%)	527,138,816	63-Sector-Translation	Block Mode
Micropolis 1538	Ultra 12F32	22.896	6,502	1,524,376	924,074 (42,97%)	528,171,008	63-Sector-Translation
Micropolis 1538	DTC 6282-24	22.071	6,746	1,965,410	1,878,640 (87,36%)	528,171,008	63-Sector-Translation

* in brackets percent of 2,150,400 bytes/s, the drive's theoretical sustained data throughput with 70 sectors per track

Disk Drive	Controller Card	Access Time (25.135ms=100)	Sector Access Velocity (5.977 MB/s=100)	Burst Data Throughput (2,370,764 Byte/s=100)	Sustained Data Throughput (1,054,813 byte/s=100)	Storage Space (527,964,570 byte=100)
Micropolis 1538	Ultra 12C	116	86	70	67	100
Micropolis 1538	Ultra 22CA	112	89	199	89	100
Micropolis 1538	Ultra 22C	111	89	207	94	100
Micropolis 1538	DTC 6295-24	106	94	102	94	100
Micropolis 1538	DTC 6290-24	99	100	77	93	100
Micropolis 1538	Ultra 12F24	93	106	66	123	100
Micropolis 1538	ACB-2322D	93	107	64	104	100
Micropolis 1538	WD1009V-SE2	92	108	69	70	100
Micropolis 1538	Ultra 12F32	91	109	64	88	100
Micropolis 1538	DTC 6282-24	88	113	83	178	100

As you can see, some of the 20MHz controller cards, like the Ultra 22C from Ultrastor or the ACB-2322D from Adaptec, do support drives with 23MHz too. The most fast cards use track buffering, while the caching cards are slower. Adaptec, Western Digital, Ultrastor, and Datatechnology build the most fast cards, again Datatechnology is way ahead.

23MHz drives always have more than 528,482,304 byte (528MB) storage space. In order to make use of the whole storage space under the DOS operating system, controller cards have to operate in head mapping mode. Adaptec offers a virtual drive split as a method to access the storage space above 528MB. Alas, drive split leads to two partitions on the drive and it leads to a mess, if you add a second drive to the controller card.
The following table shows the results for head-mapping-mode with the Micropolis 1538 disk drive and the next table but one shows indexed values (Index 100=Average of 10 cards).

Disk Drive	Controller Card	Access Time (milliseconds)	Sector Access Velocity (megabyte/s)	Burst Data Throughput (byte/s)	Sustained Data Throughput (byte/s)*	Storage Space (byte)	Translation Mode	Remarks
Micropolis 1538	Ultra 12C	34.510	7,300	506,963	398,261 (18,52%)	894,173,184	Head-Mapping-Mode
Micropolis 1538	Ultra 22CA	30.045	8,385	5,920,102	962,062 (44,74%)	894,173,184	Head-Mapping-Mode
Micropolis 1538	Ultra 22C	29.488	8,548	6,288,681	964,908 (44,87%)	894,173,184	Head-Mapping-Mode
Micropolis 1538	Ultra 12F24	28.646	8,795	865,148	820,466 (38,15%)	894,173,184	Head-Mapping-Mode
Micropolis 1538	Ultra 12F32	28.189	8,937	841,071	867,531 (40,34%)	893,599,744	Head-Mapping-Mode
Micropolis 1538	DTC 6295-24	27.718	9,073	3,155,461	986,415 (45,87%)	893,599,744	Head-Mapping-Mode
Micropolis 1538	DTC 6282-24	26.099	9,636	673,648	716,780 (33,33%)	893,599,744	Head-Mapping-Mode
Micropolis 1538	WD1009V-SE2	25.403	9,900	1,637,209	1,129,678 (52,53%)	893,599,744	Head-Mapping-Mode
Micropolis 1538	ACB-2322D	N/A	N/A	N/A	N/A	N/A	N/A	Drive Split Mode only
Micropolis 1538	DTC 6290-24	N/A	N/A	N/A	N/A	N/A	N/A	no support for Head-Mapping Mode

* in brackets percent of 2,150,400 bytes/s, the drive's theoretical sustained data throughput with 70 sectors per track

Disk Drive	Controller Card	Access Time (28.762ms=100)	Sector Access Velocity (8,822 MB/s=100)	Burst Data Throughput (2,486,035 Byte/s=100)	Sustained Data Throughput (855,763 byte/s=100)	Storage Space (893,886,464 byte=100)
Micropolis 1538	Ultra 12C	120	83	20	47	100
Micropolis 1538	Ultra 22CA	104	95	238	112	100
Micropolis 1538	Ultra 22C	103	97	253	113	100
Micropolis 1538	Ultra 12F24	100	100	35	96	100
Micropolis 1538	Ultra 12F32	98	101	34	101	100
Micropolis 1538	DTC 6295-24	96	103	127	115	100
Micropolis 1538	DTC 6282-24	91	109	27	84	100
Micropolis 1538	WD1009V-SE2	88	112	66	132	100

In the head-mapping-mode the Western Digital WD1009V shows it's superiority. As a caching controller card, it's able to maintain burst data transfer, but not at the expense of the access time, like most other caching controller cards do. It's even faster than the DTC 6282-24.
One caching controller card, the DTC 6295-24, with EISA interface and 2 MB cache ram is able to keep up with the track buffering cards. It reaches a very good third place.

Setup and Benchmarks of Several ESDI Hard Disks and Controller Cards

The Results - 23 MHz System