Z67-IDE Manager

Z67-IDE Controller Multi-Drive Boot Support In the late 70’s, Heathkit introduced the Z67 Winchester Disk Drive as shown below. It cost about $5800.00 dollars and its storage capabilities were about 11 megabytes unformatted.

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Z67-IDE Manager

Today we have the Z67-IDE Controller which replaces the original Heathkit Z67 storage solution at a cost less than a $100.00 with unlimited storage capacity. The Z67-IDE controller presents itself to the H8/H89 Heathkit computers as a Z67 Winchester Hard Drive. It employs two IDE Hard Drives or CF cards with respective IDE adapter and supports up to “32 bootable logical drives” per hard Drive or CF card for a total of 64 virtual drives on two 8GB CF cards. For HDOS the total available storage capacity is 15MB (243 cylinders * 240 sectors * 256 bytes = 14,929,920) times 8 drives x (512 bytes/256 bytes) = 240MB. For CP/M the total storage capacity is 8MB times 15 partitions times 8 drives x (512 bytes/256 bytes) = 1920MB. Because we support CP/M on both cards, then the minimum storage capacity supported is 2GB per drive for 8 logical drives per CF card.

Z67-IDE MultiDisk CF Capacity

Logical Drives Supported

2GB

8

4GB

16

8GB

32

IDE drives have a sector size of 512 bytes while the H8/H89 CP/M and HDOS OS’s support 256 bytes per sector. To avoid the time consuming calculation of LBA and sector offset for every block number, the Z67-IDE Storage Controller was designed to support two linear logical drives of 256 bytes per sector. Therefore the space required on the hard disk must be twice the nominal volume size. Since only half of the space was being used, there was room for an entire drive in the second half of the 512 byte sector. This could be managed by treating each 512 byte sector as two pages of 256 bytes. The 0 pages (the first 256 bytes) were assigned to the even numbered systems (0, 2, 4 and 6) and the 1 page (the second 256 bytes) were assigned to the odd systems (1, 3, 5 & 7). From the host's point of view, each logical drive is a different hard disk, but as there is only one physical interface, only one logical drive can be accessed at a time. The logical drives are implemented by adding an offset to the logical block number. Logical drive 0 (Drive0) LBA starts at 0x00000000 + offset on the hard drive assigned at page 0 (first 256 bytes of sector 0). Logical drive 1 (Drive1) LBA starts at 0x00000000 + offset on the hard drive assigned at page 1 (second 256 bytes of sector 0), and so on.

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Z67-IDE Manager

IDE-Z67 Multi-Disk Implementation

Hard Drive 0+n - LBA

Sector X = 256 bytes Page0

Writing to Drive0+n or Drive1+n

n=2 512 bytes

Hard Drive 1+n - LBA

Sector X = 256 bytes Page1

n=2

Reading from Drive0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30 Sector X = 256 bytes Page0 Hard Drive 0+n - LBA

Hard Drive 0+n - Data n=2

512 bytes

n=2

Sector X = 256 bytes Page1

Reading from Drive1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31 Sector X = 256 bytes Page0 Hard Drive 1+n - LBA

512 bytes

n=2

Sector X = 256 bytes Page1

Hard Drive 1+n - Data n=2

Never change the volume number using the BCD switch while the drive is mounted! Always do a System reset to change the drive number, and then boot the OS (CP/M or HDOS). The safe way is to reset the computer to set the BCD switch to the new volume number and reboot the Heathkit Computer.

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Z67-IDE Manager

The following drive configurations are supported:

As shown above, BCD Switch bit 0 is used to control the Page number and bits 1 and 2 are used to control the drive number. For selecting the page and volume and to increase the security of the hard drive data, the following operating controls are provided:  BCD Switch to select the active drive. The switch is read at power-on and when reading and writing to the hard drives to calculate sector offset.  Write-Protect Switches. These switches are read before performing a sector write operation on the hard drive. If the switch is enabled, it will ignore the write and will report to the OS that the operation was unsuccessful by sending a sense request indicating that the drive is write-protected. It is up to the application to let the user know if the write was successful or not.  Replication Jumper or Switch. The switch is read at power-on and if enabled it will do the following; o Master Drive:  Image Drive0 to Drive1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18, 19,20,21,22,23,24,25,26,27,28,29,30,31. o Slave Drive:  Image Drive0 to Drive1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18, 19,20,21,22,23,24,25,26,27,28,29,30,31. Note: The replication routine assumes that the user “only” created a bootable Drive0 system on each IDE hard drive with all required files. This is a time saving routine for HDOS which it takes about 45 minutes just to format a single 16MB partition. 4|Page

Z67-IDE Manager

Z67-IDE Manager GUI for Windows

After configuring the serial port, click on the “Is Z67-IDE on-line” switch to detect the presence of the Z67-IDE Disk Controller that is attached to your Heathkit Computer. Make sure the Z67IDE serial port is connected to your PC serial COM port. Once the Z67-IDE board is detected then all the tabs will be visible to manage the Z67-IDE hard drive controller.

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Z67-IDE Manager

Z67-IDE is online with the Z67-IDE Manager Application. Also it displays the status of the write protect switches. In order to avoid polling the Z67-IDE for such status, the switch must be use to get latest status on the Z67-IDE and on the WP switches. This is to avoid slowing down the Z67-IDE hard drive controller while is reading and writing to the hard drives. The Z67-IDE uses three interrupts; INT0 – for hard drives reads and writes INT1 – to TX characters to the terminal INT2 – to RX characters from the terminal The Z67-IDE manages all three interrupts while reading and writing to the disk. Getting a status from the Z67-IDE while formatting, reading or writing a HDOS or CP/M partition is supported, but the operation might be slow because the hard drives has the highest interrupt and the serial port has the lowest interrupt.

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Z67-IDE Manager

The Backup/Restore tab allows the user to backup or restore the IDE hard drive contents into a file. This process is over the serial port at 9600bps and it is going to take hrs to complete each task. The progress indicator will give the user an indication on how much % has completed.

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Z67-IDE Manager

The Format tab allows the user to erase the whole contents of each hard drive. This task is time consuming and it may take several hrs to complete per hard drive.

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Z67-IDE Manager

The HD’s Information tab displays the vendor hard drive information and the total capacity in bytes for each hard drive. This is to verify that both IDE hard drives are on-line. Note: Display both hard drives vendor information at the same time, instead of one at a time.

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Z67-IDE Manager

The Read LBA# tab is used for debugging purposes. Sometime there is a need to verify that the correct information is written to the proper sector after writing a known pattern (E5).

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Z67-IDE Manager

The Image HD’s tab is used to create an exact copy of the Master Hard Drive. Once it is enabled, it will copy all the information from the Master Hard Drive into the Slave Hard Drive. Make sure that the correct Hard Drive is set as the master and not the other way around.

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Z67-IDE Manager

The RTC tab is use to control the DS1307 RTC. It allows to setup the correct time on the calendar clock.

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Z67-IDE Manager

The Replication tab (in progress) allows the user to replicate the contents of boot System 0 on both hard drives into all supported partitions. In HDOS it takes about 45 minutes to format a single partition. Once a single bootable partition is available, then it replicates itself across all partitions available depending on the hard drive capacity. It is normal to see error messages during this process due to probing to find out the boundaries of the supported storage device.

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Z67-IDE Manager

References: 1. http://koyado.com/Heathkit/Z67-IDE_files/Z67-IDE%208%20drives%20support.pdf a. Configuration for 8 logical drives 2. TBD a. Configuration for 32 logical drives

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