Sigma Electronics Systems Display Generator 5564

Johannes Thelen johannesthelen at
Thu Mar 5 15:14:16 CST 2015

Cool find!

> One of the full-width cards is something like 'area fill'. So it does that in hardware too?

Yes, probably, it is not that big trick (in theory). Example Amiga's custom chipsets was capable for area fill (line mode), and btw, prototype of that custom chip set was made from TTL chips:

Please send some photos of that Sigma's miracle!

- Johannes ThelenFinland
Before microcomputers blog (Finnish)

> From: ard at
> To: cctalk at
> Subject: Sigma Electronics Systems Display Generator 5564
> Date: Thu, 5 Mar 2015 18:34:30 +0000
> Can anyone tell me anything about the subject: line? It seems to be a high-end graphics terminal from the 
> mid 1970s. I have found the electronics unit while unpacking here, I think I have the keyboard (with a little
> built-in joystick?) somewhere too. I don't have the monitor, but I am guessing it's TV rates.
> Pysically it's just a metal box (about the size of a 4U rack unit without flanges). There is nothing on the front
> panel. The back panel has the on/off switch and connectors for a keyboard (DA15), 'Digital Video' (ditto),
> Host and Downstream RS232 ports (DB25, of course) Host and Dowstream current loop ports (DE9), 3 video
> outputs (BNC, I assume these can be used as R,G,B), mix video output (ditto) and video input (my guess is that
> the terminal video can be overlayed on some other video signal, again a BNC).
> The top cover comes off with 2 screws. It reveals very little apart from a massive linear PSU. The interesting
> stuff is exposed by removing the front panel (4 screws) which gives access to the card cage. There are 2
> columns of half-width cards at the top, then about 7 full width ones. 2 of the half-width cards are wire-wrapped
> not PCBs. I forget what they do, one of them seems to be the video timing/sync counters. On other half-width
> cards are the processor (6800), ROMs (lots of EPROMs),Comms, video output (resistor DACs, etc) and
> a 'vector generator' which I guess is to draw lines, it's just a lot of of logic ICs, no microprocessor.
> One of the full-width cards is something like 'area fill'. So it does that in hardware too? The others -- and there
> are half a dozen of them -- are 'Pixel Store'. Each has 16K*16 of DRAM and a 16 bit ALU (4 off 74181).
> I hate to think how much this cost when new. RAM and ALUs were not cheap!
> -tony

More information about the cctalk mailing list