2 Feb
2014
2 Feb
'14
2:44 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of emanuel stiebler
Sent: 02 February 2014 20:21
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Trouble Getting MFM Controller to Write
On 2014-02-02 15:42, Robert Jarratt wrote:
the
As you may be aware I am trying to build an
emulator for MFM disks
(mainly DEC RD5x disks) using an FPGA. Things have been going
moderately well in that I have managed to get the MicroVAX 2000
formatter (TEST 70) to recognise the appropriate RD5x disk by counting
cylinders.
>
>
>
> However, now I am at the stage when I want the controller in the 2000
> to write something. I am trying to use the formatter to write data to disk.
I have checked all of these, but when I get back to this next weekend I will
check again. I don't think the track counting would work if most of those
were not right, but it is still worth another check.
Regards
Rob
However, the WRITE GATE signal never gets
asserted.
I cannot see what is stopping the 2000 from asserting WRITE GATE. I
have implemented the Index signal which looks right on the
oscilloscope, and of course all the signals for track selection. I am
sending dummy data on READ DATA (all logical 0s as far as I can be
sure). I am as sure as I can be that I have the right pin on the
connector (32 according to the 2000's tech manual).
Just the obvious, but:
seek_complete is low?
ready is low?
track 0 is low?
index you said is OK,
write_fault is low?