To make a long story short: this is a 65816 system using an ATX board as platform. It should be able to use PC ISA cards. My C64 had no problems with various cards, including the MDA and CGA video card. As a teaser:



Why an ATX board? Cases, power supplies, keyboards, drives and cards in abundance. Now I only have to focus on the board.

More details you will find on: http://www.baltissen.org/newhtm/65816atx.htm

Here you will also find the full schematics as PNG. If interested, the Eagle 7.7.0 schematics are free, just email me.

I am not going to produce the boards yet. I first want to optimize the layout yet.

For Dieter aka ttlworks: the reason I asked you if you card can be tweaked to handle VGA is simple: I want a VGA card for this system. I have various option:
- hack an existing VGA card. Advantage: it is only a matter of software. Disadvantage: will probably work only for this type of card.
- build one from scratch starting with Ben Eater's very good explanation: https://eater.net/vga
- use a bit more sophisticated design: http://debuginnovations.com/TTL_Terminal/home.html
- use a MCU that generates a simple VGA text screen and that uses RS-232 as input
- hack a MDA card (maybe my favorite)
Ideas and designs are welcome!

Have a look and then shoot.

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I built one of these, which produces 80×24 VGA. I posted something about it here.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

I know, that's how I found about it in the first place. And I was quite amazed that a MCU could do that. This would be the quickest solution of all options.

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Initially for my 6502 project, I used an ATmega 1284p to generate 320x220x1 PAL composite video, and if you want colour VGA, then have a look at this project:

http://quinndunki.com/blondihacks/?p=1154

The generic stuff for Arduino is called ArduTv, or TVout if you want to do searching for them too.

-Gordon

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--
Gordon Henderson.
See my Ruby 6502 and 65816 SBC projects here: https://projects.drogon.net/ruby/

Thanks! I was just wondering if those two little text files were all the code that was needed. Hey, the file is calling testRender1, 2, 3 and 4 and they are nowhere to be found!

There is a disadvantage: it is graphics only. IMHO you loose to much time when you only want to output some text because you have to calculate in one or another way the position of every pixel. But I like the simplicity of the design, particularly the interface with a system.

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I'm a little put off by Ben Eater's design—it uses a lot of hardware for what it does. Geoff Graham's design, being essentially single-chip, would be much easier to integrate into a 6502 project. Plus, as discussed in my topic on the build, if you don't like VT-100 emulation you can change it to something else.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Not knowing if my board works at all, VGA has not my priority. If I would use it, I would build an ISA card base on this design. As interface between the MCU and the board I would use a 6551 or a 16550.

Question: is the PS/2 connector needed? I can imagine that it is maybe needed for a first setup. Connecting a keyboard to the MCU for one time I can understand.
OTOH a setup can be configured into the binary that is loaded into the MCU. I hope you can enlighten me on this. TXS!

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Having the keyboard available is useful for loop-back testing the serial-in connection.


There are defaults that are loaded when first powered. I see no reason why they couldn't be changed to whatever you want. It should be a simple matter of editing the relevant source file and compiling a new binary.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

Ruud, the PCB layout looks nice, and I think that routing it took you some time.

Unfortunately, when resorting to PC related stuff, there are some drawbacks:
The hardware simply evolves too fast (ISA: 1981, PCI:1993, bitserial PCI_Express:2003).
Good old parallel ATA from 1986 went replaced by bitserial SATA in 2000.
Remember the simple 72 pin SIMM DRAM modules ?

If you buy ISA cards, they might be "used and of obscure origin", and for properly initializing them (please forgive me this heresy),
one probably might need an 8086 emulator running on a 6502 (as in "compatibility", 'compatibility', and compatibility).

Nowaday, one would need at least "USB2.0 master" and Ethernet functionality.
Keyboards and mice eventually wouldn't support PS\2 anymore, it's going to be "USB only" at some point.

Building your own graphics card with a DVI\HDMI port later would be going to be quite a challenge.


Please don't get me wrong:
I'm not trying to discourage you, I'm just listing what prevented me from building something like an ATX 6502 board.

BTW:In the long range, replacing the battery by using a solder iron every time would limit the fun.
There are clips for CR2032 batteries, for instance Mouser has the Renata VBH2032-1.

Very neat! I'll be keeping an eye on this one

A week? Spare hours, not continiously.


I have "tons" of them.


That would be the case with VGA cards. And I first had my doubts being able to use one of them, because of the onboard ROM. But all cards should be IBM's first VGA card compatible AFAIK and that should enable me to write software that should work on almost all cards for the "simple" 640x480 mode. "3*should" says it all.
CGA, MDA, FDC, HDD, LPT and COM cards should be no problem. But I have no idea so far how to handle network cards. If it is simple, fine. If it isn't, I won't miss it.


I consider it as a lot of fun and that is the most important part of any project, isn't it?


Of course I mean to use a clip and I thought it was one. But having a second look, I see that you are right. I'll search the library again and otherwise I'll create one my self. Thank you for pointing me to this!

If you have any remarks on the wiring, please tell me! That's the only point I'm not sure about.

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I think for non-trivial cards (NICs, etc.) your best bet would probably be to look at older freenix sources, since they had to A. support a reasonable swath of contemporary PC hardware, and B. run without relying on real-mode ROM/BIOS functions.

Can't tell much about the wiring, sorry.
Ruud, your schematics are a bit _big_, and it's easy to lose the overview.
But now some more (hopefully constructive) comments:


That VT82C42 heyboard\mouse controller seems to be very exotic.
For instance, PIC18F452 has a parallel slave port, but PIC coding ain't fun.
BTW: I would put 100 Ohm resistors between the PS\2 connectors and the chip, and add protection diodes to the chip.

DS12885 real time clock is a bit "outdated", and the bus interface isn't a nice one.
Try DS1511Y instead (5V, narrow DIP28). //DS1511W is 3.3V, take care.

To me the 29F010 EEPROM looks a bit small.
Mouser has Microchip SST39SF010A, SST39SF020A, SST39SF040: PDIP32, 70ns, 5V.

FTDI has some chips with USB host functionality.
Vinculum can interface to a USB mouse, but when it comes to handling USB sticks it can only open one file at a time.
We were not pleased with the Vinculum II IDE, and of course the chip is completely different from the Vinculum.
Maybe you should take a look at the FT313.

For Ethernet, take a look at the ENC28J60 section of Daryl Rictor's homepage.
Microchip ENC28J60 does 10BASE-T, PHY already on_chip, the SPI is sort of a drawback.
When using the shift register of a 6522 and a 74164, something could be improvised. BTW: 74LVC245 makes a neat 5V\3.3V level translator.
But one needs to be a bit paranoid about the SCK to rising edge /CS timing (when doing something wrong there, all registers on the chip could be read/written except the PHY registers).
//Another option to "6522 + 74164" would be using 65SPI for implementing the SPI.

74LS154 seems to be out of production, and it's hard to tell how long 74HCT154 would stay in production.
Would suggest to replace the 74154 by two 74138, maybe this also gives a nicer PCB layout.

Speaking of it, to me the PCB signal traces at the ISA connectors look a bit thin.
I had that habit of making the last segment of a trace 32 mil wide or such when routing it to a connector.
//We could assume that plugging/unplugging an ISA card causes some mechanical stress to the PCB traces.

Out of paranoia, I would suggest to add an uni_directional TVS (transient voltage supressor) diode between +5V and GND close to the power supply connector.
Something like SMDJ5.0A.
If anything goes wrong with your switchmode power supply (already had this), it increases the chance that the chips on the PCB might survive.
//Whetter adding TVS diodes to +12V, -12V and -5V or not is debatable.

On a 2 layer PCB, you probably don't have a chance for distributing GND and +5V in a different way.
Using a 4 layer PCB (with GND and +5V at the inner layers) would increase signal integrity and reliability a lot... but it also would increase cost.
Let's see... ATX is 305mm * 244mm.
multipcb: 2 layers 4WD 121€ (2 layers 13WD 100€), 4 layers 5WD 200€ (4 layers 13WD 166€). //'WD' means 'workdays'.
Edit: dang: "We sell solely to business customers and public institutions"

Hmm... if you should be running out of PCB space, there are 5V TTL oscillators in DIP8 form factor at DigiKey,
for instance ACH-8.000MHZ-EK and ACH-14.31818MHZ-EK.

BTW: At ca. 30€, Meanwell RQ-125B doesn't seem to be much more expensive than a new ATX power supply at ebay.
+5V\11A, +12V\4.5A, -5V\1A, -12V\0.5A. Would it make sense to have screw terminals on the motherboard ?

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?