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RCA Spectra 70 Series

Chuck(G) said:
The Spectrolas were notable for being fodder for custom microprogramming.
Click to expand...
I dug back through the documentation, and I don't see a user microprogrammable hardware option. The hardware docs I have just show machines with 53 bit ROM
Were the small models like the 360/25 where microcode existed in core, and was vertically microprogrammed?
 
Well, you might see one working in the future. Currently fixing the Power Supply of a Siemens 4004/15 which is a rebranded Spectra 70/15 with 16k memory option.
As such I am in dire search of any hardware documentation. No way to know yet what else might be broken...

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what we have probably won't be of much help except for the channel information
the 70/15 is a 16-bit machine that looks roughly equivalent to a 360/20
 

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I got:
4004/15C with 16kB RAM
4004/551 with Interface for CDC
2x CDC 4004/564 without Media
4004/216 Interface and Teletype
4004/243-10 Printer
4004/234-10 Card Punch
missing the 4004/4235 Card Reader, still looking for it
And missing ALL the external cables...

Currently fixing the PS in the /15 - no pos. Voltages, neg. 30 and 42 out of range (Power Transistors BC seems shorted, Getting at it, should be possible to fix without Documentation. Of course, DC Plugs to System are currently Disconnected.

I made many pictures but have not cut ans resized them to a more suitable file size yet.
 
I got quite some information down to the "User/Programmer" level that came with the system and from Bit-savers, but nothing deeper. The Connector Signal Assignments of the "RCA Spectra 70 Standard Bus" would be very helpful and should be the same for all the 70 series models, right?
I know that the bus has 9 data out lines, 9 data in lines and a handful of control lines. The functional description I got is very thorough.
 
One more Picture. In the CHM texts it is mentioned that side panels are missing. Well, they are missing by design, the cabinets were usually placed in a row and bolted together, thus there are only two side panels in total...
 

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Update:

by now the Power Supply and its Sequencing has been fixed and is working.
One or a few bits in the MAR seem stuck 'ON'. They cannot be Reset with Clear MAR.
M seems to work fine, one can display and set the Registers.
Core Memory sometimes seems to work, mostly not.
Peculiar: Whether Core Memory works or not, is determined at Power-On. Also which bits of MAR are stuck.

Most Transistors are NPN Silizium, but a few Germanium are there, probably due to an availability issue. NPN Germanium seems a bit odd.
 
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