Hardware / National Computer Ltd. / NDC-5027

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A simple 8 bit controller from NCL

So far I couldn't find any further manuals about this controller on the internet. There is only the usual overview on "Total Hardware 1999". Attention: This overview has a mistake! See drive 4/612 (i.e. Seagate ST-225), see below.

System Resources

BIOS

The BIOS is basically of type 2764, i.e. it is 8 KByte in size. On this card two EPROMs from MITSUBISHI (M5L2764K) are used. Sticker on BIOS: NCL 5027 CN-12-01. Sticker on second EPROM (Microcode): NCL 5027 00-00-04. The BIOS contains the following string:

NCL01 (C) COPYRIGHT SPACETECH 1984 (C) COPYRIGHT SVC 1985

Figures

NDC-5027
NDC-5027

Like the IT-805 controller, the NDC-5027 has a good low-level formatting routine, but you have to select the disk drive with the switch (SW1). You can also split the drive into 2 logical units. I did not test.

NDC-5027
NDC-5027 / Hard disk initialization
Start low level formatting with: DEBUG (ENTER) -G=C800:5 (ENTER)

In contrast to the CTT IT-805 (1:1), you can only set the interleave factor to 1:3. More is not possible. I checked it with SpinRite II.

Manuals