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The project so far.


Experienced Member
Dec 11, 2010
So let's talk now about the status of the project.

The status of the project is that yesterday night I finished re-checking everything and tried to create "the netlist" and see what was coming out, after a bit of a battle with some missing footprints, a couple of mis-labellings and a silly thing I got nuts for over 30 mins to find out about a strange error I was getting.

Turns out when I made the component "T11 CPU" I accidentally ( cut & paste error ) put two different pins the same number and that was making the program complain.

Initially I was thinking in going for "usual wire wrap" to make a test prototype but with some reluctances, giving the high number of connections necessary the question of "would it be faster to solder all those wires or try to make a pcb ?".

I decided to go for the PCB option, also to improve my PCB ( by hand ) routing skills.

About that ok "I am not a monster in doing PCBs", but as everyone says "the more you do the better you get" so I better continue doing it, I am quite good I'd say in actually photo-print and etch them.

Usually I buy some pre-sensitized boards, I print stuff on translucent paper using my HP Laserjet PI505 printer, I expose them using my home made UV unit ( modified flatbed scanner with 3x15W UV tubes in - 1 min 40 sec exposure time ) and then I develop using classic NaOH solution ( 10g x 150 ml water ), finally etching with sodium persulphate in a bain marie of hot water.

This time I am thinking to actually prepare some copper board my own using the photoresist in aerosol form ( spray ) I want to get an even better quality.

Of course being all "home made" this limits me to two layers only PCBs, I so far settled for 92x72 mil pads, 35 mils tracks with 15 mils for across pins and 50 mils or more with ground/power plane when possible, drilling by hand using an RS small drill.

I plan for the moment to make all this stuff fit in a 1/2 Eurocard ( 100 x 160 mm ) the components densitiy in this case is not super big yet not even that small.

I am still thinking if I should add some sort of edge connector to the thing ( so to have the possibility to connect it to a 'backplane' of some sort and then eventually add/modify some stuff in the future ) or for the moment "just to have a go at it" forget about it and do the stuff.

Thing is, adding a connector would mean lot more routing to be done to port all the signals there, I was thinking in not adding it in the schematics now but maybe add it as a component route signals "as best as they come from the PCB" and then back-annotate it and map back what I've done in the schematics.

Hum, not sure, still thinking about it.

As I tried yesteday the netlist seems to have about 103 connections, maybe I should try a components placement and see how things could start to look, however just to place the components it's going to take probably a couple of hours.

I'll post later some updated pics of the stuff.

Ah there been a bit of PM conversation about emulating a RL11 disk, basically RSX11M+ thinks it should be not too difficult, he's going to find some info for me so to understand what could be needed.

Also looks like "it would be a good thing" to someway make that UART I attached being seen as the ODT console, now this I think could be done but I need to think/experiment with the VHDL, I think actually I should do this before to continue further ( with the HW ) because I hope I won't have to change something and/or run of out "resources" in the CPLD.

I guess I'll be going to spend the next 30 mins or so trying to check that out, then we'll have to go in town, there's not only HW in this day :lol: