28 Jun
2004
28 Jun
'04
9:48 a.m.
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