User:Electron9/Commodore D9060



The Commodore D9090 Hard Disk was the first and last family of Hard Drive that Commodore made for both the home and business market. The electronics is identical in the D9090 and the D9060 unit. The only difference is the size of the installed hard drive mechanism. And a jumper set on the DOS board to distinguish between 4 or 6 disk heads.

Technical data

 * on the D9090 25% of the hard disk is never used

Internally the system was made up of Four major parts:
 * 1) CBM DOS 3.0 PCB
 * 2) SASI Controller
 * 3) Hard drive
 * 4) Power supply

Input voltage: 100, 117, 220, 240 V AC

Power supply
4-pin plug & cable - wiring and voltages follow world standard for large drive power cables, but colours are not standard.

CBM DOS 3.0 PCB


This DOS PCB is made up of several major electronic components: Disk system buffer = 4 kB (8 x 2114 SRAM chips) Commodore device number selectable between 8 - 11 (on IC 7H : 6532)
 * 3 x ROM's (Two for CBM DOS communication with host computer, One for SASI communications for Hard Drive formating- Track & Sector layout, 4 or 6 heads.)
 * 4 or 6 heads is selectable only by a hardware jumper located on the front of the DOS PCB.
 * 2 x MOS 6502 Microprocessors
 * 2 x 6532 RIOT I/O Chip
 * 1 x 6522 I/O chip

Connecting 2 hard drives to one (SASI) controller
Capable of managing 2 x MFM hard drive mechanisms, which is communicated to the user as two combined directories, with one header number = 0 and the other header number = 1 Which is strange because most Commodore drives of this era required each separate disk directory to be called individually with a command LOAD"$",8,0 and LOAD"$",8,1 for the two drives that reside in device 8. As a result it looks like the DOS was never fully completed by Commodore, which is evident when you save to the hard drive only to find that the two directories overlap for the one device and the number of blocks free is only displayed as if only one hard drive is in use.

SASI controller


The main brain driving this controller is the AMD 'AM2910' (a high-Performance 8-bit Slice Microprogram Sequencer) The SASI Technology was invented by SHUGART that became SEAGATE. SASI which eventually became standardized and is known today as SCSI. They also went on to create the company Adaptec.

Hard drive


Internally the system had a transfer rate of 5.0 MB/s from the hard drive to the CBM DOS 3.0 Controller PCB. TANDON became Western Digital (WD).

Cylinders = 153 (per hard disc) 6 head drive contains 3 x hard discs, 4 head drive contains 2 hard discs.

Sectors per Cylinder = 192 (D9090) Sectors per Cylinder = 128 (D9060)

Sectors per track = 32

Bytes per sector = 256

IEEE 488 bus
[24 wire parallel cable] IEEE 488 (transfer rate 1.2 K per second from D9090/D9060 to Computer - 8 Data lines) D9090/D9060 Hard Drives can be daisy chained, the same as the Commodore serial bus used on the 1541, 1571, 1581 Family of floppy drives.

PET
The D9090 & D9060 were designed for usage primarily on the Commodore PET Family of computers, but because these Metal cased family of machines were obsoleted by the VIC-20 and the Commodore 64. The greatest demand for these drives came from the biggest home computer user market in the world at the time, ie - The Commodore 64 user. As a result, Several companies built interfaces that effectively give a VIC-20 and Commodore 64/128 an IEEE-488 Port. Commodore created a VIC-20 IEEE 488 cartridge with model number "VIC-1112".

IEEE-488 for Commodore 64/128
The Commodore 64 IEEE-488 Cartridges were made by various companies, but Commodore themselves never made one for the Commodore 64/128 family.

Some other Interfaces, no pictures available:
 * E-LINK Serial ot IEEE Interface. (contains 65C02, 6522 and 4 kB ROM)
 * Buscard II Interface. (contains a 6532, 6821 (PIA) and 8 kB ROM, and a 256 byte PROM)
 * INTERPOD - An Interface box, that converts IEEE-488 to CBM (IEC) serial & RS-232 serial.

Commodore 64/128 usage
The D9090 & D9060 Hard Drive was highly sought after in the early 1980s by the huge number of people using the Commodore 64 and Commodore 128 who wanted to taste the luxury of having all their utilities and games in one place, and being able to load these files and games at high speed, with an overall loading speed 5 times faster than the standard drive that most people were using Commodore 1541 with "664 BLOCKS FREE" (166 kB). Where as a D9090 hard Drive has 29 162 BLOCKS FREE !!! (7290 kB). Which is why many bulletin board systems (BBS) were set up using these hard drives because they could access information so fast and could hold so much information compared to the 1541 disk drive which could only access 170 kB on one side of one disk at one time. By the late 1980s, the Commodore 64 had obsoleted all other Commodore 8-bit machines mainly because of the sheer number of users world wide and also the market support from so many 3rd party software & hardware companies. As a result, the older IEEE-488 Disk Drives & Hard drives were being acquired by large numbers of C64 owners to connect to their computer using an IEEE-488 Interface. This has put pressure on the supply of these devices as now a days they are wanted by both Commodore 64/128 users and also needed by people using the PET family of machines, that these drives were specifically designed for.

Partitions and sub directories
Due to the structure of the onboard DOS 3.0, there is only one main Partition which contains the directory and all the saved files. There are no sub directories so eventually you run in to trouble when you type LOAD"$",8 and LIST, the directory list fills the screen and then scrolls away. You can pause the directory listing as with any Commodore computer. But if you have 100 files saved. Then you have to wait some time until the directory listing reaches the bottom.

Price when new
The oldest price list I found was titled "Commodore Price List 1-september 1983"
 * D9060 Hard Disk Drive 5 Megabytes  =  $4648 (Australia),  £1995 (UK)
 * D9090 Hard Disk Drive 7.5 Megabytes = $5813 (Australia),  £2495 (UK)

Internal explained
Any 4 or 6 head MFM drive mechanism can be used as a replacement mechanism.

Formatting

 * D9090 (6 heads) Formatting takes 1 hour and 20 minutes !!! so be very very very very patient...
 * D9060 (4 heads) Formatting takes about 1 hour !!! so again you need to be very patient...

Software, drivers & Technical support
Commodore 64 based software for drive management, file transfers & repair diagnosis is available from the SPACE_TAXI website.

A program and cable exists which lets you use a common IBM compatible PC as a Virtual IEEE-488 hard drive, from here: baltissen.org/htm/cbmhd.htm