C H D - Q22-Bus - ATA Disk Adapter

Q22-Bus - ATA Disk Adapter - A tour around the board |
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Starting at the upper left side, the gold fingers are for the power supply. I am using a spare PC power supply to power the adapter and the drive.

The two headers are for the Q22-Bus extension cables and are equivalent to the M9405 Cable Connector. Since this is a "chassis", the resistors terminate the Q22-Bus.

Below the headers and to the left is a 32.000MHZ clock. The green LED is connected to the Qbus BSYNCL signal. Since this signal is asserted during each bus cycle, it gives a good visual indication of the bus activity. Next is a row of DS8838 Bus Transceivers. DEC seemed to prefer the DS8641, but I could not find a source for them. Further right are two 74ALS244 Tri-State Buffers. These devices connect the adapter Bus A to adapter Bus B.

In the middle of the board is the ATF1508 CPLD. The header to the left is for the In System Programming (ISP) port. One of the reasons for selecting the ATF1508 was that it was in system programmable and the the programming tools were readily available, in other words free.

At the lower end of the board is the IDE connector. Next to that is the drive activity LED.

Q22 ATA Adapter - Component Side

Revised: 30 Dec 2001
© MMI CHD