Aim-65 video card mystery

[Hugo Holden]

I don't recall if someone posted a pointer to the video card so here it is:
http://retro.hansotten.nl/uploads/fi...Controller.pdf
Dwight

Dwight,

Yest that is the one.

I think it is a very impressive card. I have been reading about its functions & options.

Rockwell made it so it would serve the RM-65 platform, but in addition, they were good enough to make it compatible with the AIM-65 computer. So with the adapter card (I'm working on a replica of that now, will be finished in a day or two) , it will make a wonderful addition to the AIM-65 computer, the Adapter + the CRTC video card. The functions/option of the video card are documented in the Rockwell book.

I plan to write up the project in great detail. If it is successful, it would make a great kit for AIM 65 owners. Member Dfnr2 is helping me with photos of the video card and the ROM dumps.

I will keep posting progress as I go.

My talented pcb maker can either make the pcb's or provide the gerbers, if I ask him in advance, for a particular project. We have a good relationship. I do the artwork (on a non pcb making platform as high res .jpeg images) and give him the images. He then he plays Altium (like a piano) and brings the board into reality. This is how those "dead replica" Dazzler boards were made. I have to burn the midnight oil to make the images, but it is wort it to help preserve this wonderful vintage computer technology.

Hugo.

[Hugo Holden]

I have made some progress. I have replicated the top and bottom track layout of the adapter board. I have attached an image of the overlaid tracks & components. It took some hours to do it.

I have to check it carefully for errors, before it goes off to my pcb maker. They next job is the CRTC board which will take longer as it is much more complex.

One of the more difficult parts to get is the right angle 44 way connector, plenty of straight ones out there. But I can make one out of the type intended for wire wrapping as they have long pins.

[dfnr2]

Beautiful work!

[MikeS]

Boy, you guys are really into doing it the hard way

But seriously, I do understand the satisfaction of reproducing original peripherals etc for our vintage hardware and admire the folks who come up with some of the impressive examples out there.

Here's a Rockwell app note describing a DIY video interface for the AIM65, with schematic and driver source code:
http://cini.classiccmp.org/pdf/Rockw...500n12-CRT.pdf

But for folks who only care about using and playing with the old hardware, here's what I use for video output on my AIM65s if I don't need a computer connected for loading/saving data/programs over RS-232:

https://geoffg.net/terminal.html
VGA/composite, PAL/NTSC, 24/36x80 (VGA), Graphics, and an RS-232<>USB converter as a bonus ; about $25
Needless to say, to use it as just a display you can omit some parts and just change the display vector in the AIM65 monitor.

BTW, I also use a modified version of this to display full 24x80 screen video on my 8x40 Tandy M100 portable.

For disk, RS232 and parallel printer I use this little board, originally just meant as a handwired beta version but I haven't gotten around to making a PCB yet:
5050IF3.jpg

It provides RS-232, cassette, CBM1541 disk drive and parallel printer interfaces.

[Hugo Holden]

Boy, you guys are really into doing it the hard way

But seriously, I do understand the satisfaction of reproducing original peripherals etc for our vintage hardware and admire the folks who come up with some of the impressive examples out there.

Here's a Rockwell app note describing a DIY video interface for the AIM65, with schematic and driver source code:
http://cini.classiccmp.org/pdf/Rockw...500n12-CRT.pdf

Hi Mike,

Thanks for posting the link. It is not the hard way as it turns out.

There are about three or more reasons why the RM65 video board is a much better proposition from my perspective. Partly because I'm a "hardware person" and I struggle a lot with the software side of things and I am not very good at that side of things.

In the case of the r6500n12-CRT I would have to design the pcb from scratch and that takes a lot longer than building a replica of the RM65 board, because I have good photos of the tracks of the RM65.

The RM65 CRTC does not require a program to be assembled and run, using up space in the AIM-65's RAM. The control program for the r6500n12-CRT has to be loaded into the AIM's RAM to get the video system running each time the AIM computer is booted. That program would have to come via the cassette tape or an RS-232 link to another computer( I have not managed either of those things with my AIM-65 yet !)

On the other hand the RM65 has the functions and options in firmware on its ROMs and in addition to this has more extensive video options. It is a very sophisticated board.

So the beauty of replicating the RM65 CRTC and its adapter is that is saves an item of Rockwell History, and "simply plugs and plays" on the AIM65 expansion connector.

This leaves the rest of the AIM-65 running normally without the requirement to do much, except turn on the machine and some minor setups. Making the RM65 CRTC a totally wonderful add on.

Though I guess the software for the r6500n12-CRT could be put in some ROM that replaced some of the RAM on the AIM-65 board, could be a way to do it but that would be a longer process to get working for me at least.

[dave_m]

For disk, RS232 and parallel printer I use this little board, originally just meant as a handwired beta version but I haven't gotten around to making a PCB yet:
5050IF3.jpg

It provides RS-232, cassette, CBM1541 disk drive and parallel printer interfaces.

Hi Mike,
Please tell us a little about the 1541 interface. Is it all done in firmware? Does it have its own ROM on the AIM65? Does it support only SAVE and LOAD or does it also do .seq files, etc?
-Dave

[MikeS]

Hi Mike,

Thanks for posting the link. It is not the hard way as it turns out.
...

Hi Hugo,

No, I didn't mean to imply that the Rockwell AIM65 video board was easier to build or better than the RM65 board, I just wanted to post an alternative contemporary 'official' approach from Rockwell for general interest and comparison. I should scan and publish some price lists and other literature from 'the day' listing the many add-on boards etc.; I wonder if anyone actually has a working bubble memory module kit...

As I said, I appreciate reconstructions of original hardware but for someone wanting to just use and play with the AIM65 by far the simplest way to get a full screen display using the built-in routines is by simply redirecting printer/display output to the RS-232 port; add a .95 TTL>RS-232 converter (and optional TTL inverter), change the display vector and Bob's your uncle.

If you're actually going to load/save files over RS-232 you'll probably want to connect it to a PC anyway and use its display.

Add some memory, a disk drive, a multi-language ROM and maybe an external printer and you've got a 'real computer

Have fun with your new toy and related projects!

m

[MikeS]

Hi Mike,
Please tell us a little about the 1541 interface. Is it all done in firmware? Does it have its own ROM on the AIM65? Does it support only SAVE and LOAD or does it also do .seq files, etc?
-Dave

Hi Dave,

Yes, it uses a 4K ROM at $D000 for the AIM side that adds about a dozen disk commands; the disk side is just a standard 1541 or SD card emulator and the hardware interface consists of a 7406 and 4 resistors. The manual was on line at one time but it seems to have disappeared; unfortunately it is not a 'free' project and you'll have to contact Dave at orgwood65@gmail.com for availability/cost etc.

m

[dave_m]

Hi Dave,

Yes, it uses a 4K ROM at $D000 for the AIM side that adds about a dozen disk commands; the disk side is just a standard 1541 or SD card emulator and the hardware interface consists of a 7406 and 4 resistors.

This is very impressive project.

[MikeS]

The AIM-65 is supposed to interface to the serial world via a 20 mA current loop.

However, with the addition of an RS232 transmitter buffer, it can drive an RS232 device as per the following document:

http://retro.hansotten.nl/uploads/fi...65%20RS232.pdf.

The RS232 receiver circuitry is already built into the AIM-65 (connected to J1-Y).
...
Dave

I think you might find that the circuit in that App note has trouble above 1200bd; better to use an inverter and a $1.00 RS-232<>TTL converter to go to 9600 and possibly a little higher.

m