design is using a FPGA and currently the ST506, ST412 and ST225
disks ar supported . I decided to use the BeMicro-CV Development
Board, equipped with an Altera Cyclone®
type: 5CEFA2F23C8N. This board has 128 MB memory and thus it is
also possible to simulate MFM drives bigger than 100 MB. In my
design the MFM data is completely decoded in Real -Time,
effectively "on the fly" and stored on a Micro-SD card.
Therefore a simple HEX-Editor for example can be used for viewing
the received data. Many other design's store only the time
intervals of the MFM signals.
Problems, open issues
interface and the corresponding signals were described in detail
by the company Seagate and were widely respected.
looks quite different at data and timing format. Everything here
is incompatible. Each manufacturer has guaranteed implemented his
own track and data format which was genarated with their own
low-level format program. The following differences exist:
CRC algorithm is different, such as different preset value.
Track format: ID AM differently.
>> Track format: DATA
>> SYNC character differently.
the same manufacturer, for example, DEC. There were different
formats used . A disk , formatted with the RQDX-1 controller Disk
could not be used in a RQDX-3 environment. Furthermore, in my
design the byte order is important, big-endian (eg Motorola) or
little endian (eg DEC PDP11) and accordingly it can be selected
with a DIP switch. To be able to save the data of a still
functioning disk, the Clone Mode was also implemented. The data
from the disc will be 1:1 transfered and then saved to the
SD-Card. In the Emulator mode the data will be read from the SD
card and the disc is simulated.