RT-11 / RX-01 issues ... "almost" boots ...

The original RAM configuration is outlined below. It was used this way, and booted just fine from RK-05's in days gone by. An M7847 with 16KW A Motorola board with 6 rows of 9 4116 chips (for a total of 48KW) A Mostek board with eight rows of 9 4116 chips (for a total of 64KW) The Motorola board was originally set to the lowest 48K, the M7847 after that, and the Mostek for the highest 64KW addresses ... I reconfigured when I checked these out (I lack the actual docs on the Motorola and Mostek boards but there are only eight DIP switches so it was easy enough to guess and just verify the range via the front panel ... bus error when a non-existent address is deposited). I think I goofed on the original size of the Mostek board ... it sports two banks of 4 rows by 9 of 4116 chips (64KBytes each bank). As for the RX11 interface (M7846), I could not find config info except for a photo of a board on the web (checked bitsavers but can't find that board). My jumpers are as follows: V2 V4 V5 V7 N1 A7 A8. All other jumpers are snipped off. Power Supply: after the long-term storage in the garage that was the first thing I checked. Once had a 5V supply put out 7V so I'm paranoid about that now! The 5V and +/- 15V supplies are all good. Cheers .... Mark Professor Mark Csele, P.Eng. Niagara College, Canada 300 Woodlawn Rd., L-23 Welland, ON, L3C 7L3 (905) 735-2211 x.7629 E-Mail: mcsele at niagarac.on.ca URL: http://technology.niagarac.on.ca/people/mcsele Author of "Fundamentals of Light Sources and Lasers", Wiley, 2004 The console will geneate 2 iterrupt vectors (60 and 64 I think) for transmit and receive. They cannont be set separately, so if the DL11-W is working properly, that's OK. The RX11 will also generate interrupts. What's it set to? Hang on a second. You've got 16Kw + 48Kw + 96kw there. That's 160Kw total. The PDP11/34 (it is an 11/34 IRIC) has 18 bit addressing and can access a total of 128kw. 4Kw are used for the I/O space, so you have have a maximum of 124kw of memory (practically, most memory boards wil lautomatically disable themselves in the I/O space, so you could fit a pair of 64Kw boards, say,m without problems). But with your configuration you must have some locations addressing 2 boards, which is not a good thing. Is it? Remeebr the address show is the 16 bit program counter address. If the MMU is disabled (which it will be on power-up, and nothing is going to enable it), addresses starting 16 or 17 are mapped to the I/O space at 76 or 77. So that address is 773764. Which I think is in the bootstrap ROM. That sounds OK. Yes, The reason is that memroy boards are MUD (Modified Unibus Device) boards and take their signals from connectors A,B (this matters on machines like the 11/44 which have a 22 bit address bus, and where the addres lines on A,B are not the same as those on E). Device controllers (SPCs -- Small Peripheral Controller) take their signals from C-F. On slot 9, the A/B conenctors are the Unibus output to the next backplane (or for a terminaotr) and are not qurie the same signals as the ones on an MUD slot. In fact I think on some machines you can short out a power rail by putting an MUD card in the Unibus Out slot or a termintor in an MUD slot. I've never heard of that being a problem... Silly question... Whenever I hear of a PDP11 wit flaky memeory I think of the time I was led a merry dance by my 11/45. It turns out the problem ther was power supply related (one ofthe 5V lines was sitting at 4.4V). Have tyoy checked all the power supply voltages with the machine in operation? -tony