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Microvax KA630 cpu

DavidEngland

New Member
Joined
Mar 23, 2021
Messages
9
Location
Braystones, Cumbria, UK
I am trying to test a KA630 CPU card for a customer.
I have a BA23 chassis with PSU and console terminal unit.
The board fails on "C" on the display indicating memory error, and hence no console.
Am I correct in assuming that the board should boot to the console without any other items in the rack?
Or am i missing something?
 
C means searching for RAM, you should probably install some KA630 memory boards. There is 1MB on board, but it could be faulty perhaps?
 
C means searching for RAM, you should probably install some KA630 memory boards. There is 1MB on board, but it could be faulty perhaps?

Correct. More RAM is expected otherwise you get a "C".Install any amount of additional RAM and repeat the test.
-Alon.
 
David,

Welcome to VCFED - as this is your first post.

And I would be in Lancaster (enjoying a curry somewhere) if it wasn't for COVID-19!

Dave
 
Correct. More RAM is expected otherwise you get a "C".Install any amount of additional RAM and repeat the test.
IIRC, there's a 5-connector memory ribbon cable that connects the CPU to up to 4 expansion memory boards. So it isn't sufficient just to have the CPU and memory board - you need to have that memory cable as well. Most of the Q-bus MicroVAXen used similar cables, until the CPU bay of the chassis (in the BA440) changed over to high-density connectors instead of the normal ABCD Q-bus and there were enough pins there.
 
On a MicroVAX II, it is a 3-connector ribbon cable for connecting up to 2 RAM boards.
-Alon.
 
Thanks everone for the replies, I have worked my way through the circuit and the system does not access the on board memory, (No CAS signal on the DRAM chips) or the CAS signals on the extented memory plug. It seems to come down to the LO16MB signal is never active, so it will not access memory in the first 16MB address space. I,ll have to see if I can obtain a memory board and cables and try that. I am also waiting for another "working" KA630 from the states, so Ill see how that goes.
 
Enjoy the title while you can!

I assume you are aware that there is a DEC Legacy Event that meets from time to time in Windermere? We take over a Village Hall and fill it with DEC machines of all kinds!

Dave
 
Enjoy the title while you can!

I assume you are aware that there is a DEC Legacy Event that meets from time to time in Windermere? We take over a Village Hall and fill it with DEC machines of all kinds!

Dave

Can't wait for the next one. If David still has problems by the time of the next one I can bring along enough MicroVAX II spares to help work out what the problem is.
 
Can't wait for the next one. If David still has problems by the time of the next one I can bring along enough MicroVAX II spares to help work out what the problem is.

I am hoping to build this BA23 chassis into a fully working system, with disk drive and controller. So it would be good to find out what is available, at the moment I am stuff from Ebay, some form the states, and it is not cheap.
 
AndyG organised the NASCOM event at the retro computer museum.

I am thinking about organising an event in Worcester at some point (Boris permitting) - but I don’t want to compete with the others.

Dave
 
I'm hoping to attend one of the next UK events, I have a VT420, a VT510 or VT520, VS4000/60 and VS4000/90 that I'd like to swap. I'm not downsizing I just have several of each. I'm looking for a VT525 and some parts/cables to get my Decstation 5000 up and running.
 
Hi, everone, I've just received the KA630 from the states, powered it up on its own and afer the ususal countdown, went into console mode. So it turns out that the board will boot without external memory, just the local. I have a 8MB memory board on the way just in case the "faulty boards" are looking for something else, I live in hope.

Its nice to see some text on the terminal (Windows XP laptop running Hyperterminal)

Now I have a set of running boot roms, I am going to copy them and try them in the "faulty" ones, see what happens.

FYI, I have a universal device programmer that will do the usual PROMS, EPROM, etc as well as PALs, GALs if anyone has the need.
 
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