New subject: Upgrading a KDF-11B ROMs for MSCP Bootstrap (disassembling a bootstrap ROM?)

28 Jun 2004

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