On Jun 28, 9:24, Robert Armstrong wrote:
> I have a KDF-11B (that's the quad sized PDP-11/23+ CPU with onboard
> serial ports and bootstrap/terminator) that's too old to know how to
> boot from MSCP (e.g. RQDX/RD5x) drives. I know later versions of
this
> board could do that and I was planning to just upgrade the EPROMs on
my
> board, but all the later EPROM images are 8K bytes - my board has
only
> 2K (2716) 24 pin EPROMS. There's no way (at least no simple way) to
> install 8K 28pin EPROMs. Actually, the EPROM sockets on my board are
so
> close together that I don't think I could get 28 pin devices to fit
even
> if I did "flying leads" for the extra 4 pins.
>
> Did the later KDF-11B boards really have 28 pin sockets? Is this
> upgrade hopeless?
(Bob and I exchanged some private email earlier, so he already knows
part of this...)
No, apparently they didn't; I checked the manuals. The later
bootstraps used Motorola 24-pin 8Kx8 EPROMs (or potentially 8Kx8 mask
ROMs, which have the same pinout, though I've never seen any DEC ones).
The ones I've got are from a PDT, I think: they're type SCM90448C.
To switch from 2Kx8 EPROMs to 8Kx8 EPROMs/mask ROMs, move the link from
J23-J24 to J22-J23.
Oh, and the DU: bootstrap that I posted to the list (following a post
by Jerome) was on Monday June 14th, if you want to dig in the archive
for "Re: Qbus hard disk controller".
--
Pete Peter Turnbull
Network Manager
University of York
Received on Mon Jun 28 2004 - 13:48:46 BST