Hargle wrote:Can ethernet+CC be done in the modem slot? How many IO addresses are needed for each?
Do we need a CC if we have ethernet? I mean, wouldn't the time be updated automagically when you log into a remote computer? I thought I remember netBIOS doing that.
Eh, I'd like the ability to have my time updated without needing to be connected to another machine.
As for the ethernet, I think it would be technically possible to do it on a board for the modem slot, but you'd probably have to connect it through something like an 8255 PPI and then write a custom driver for it (I don't think any current ethernet chipsets use a small enough address space to connect through what's put through in the modem slot).
It might also be possible, if we want to stick with DIP parts (I would, since they're easier to solder), to use one of the SPI ethernet controllers that Digikey has in a DIP package along with a DIP serial controller.
I'm thinking, now, that we should seriously look at the Realtek 8019AS as an option for ethernet. I've been looking at the datasheet, and it looks like it automatically configures itself for either 16-bit or 8-bit ISA operation (and I can't find any references to interrupts being disabled).
The only way I can see for us to solder it ourselves, though, would be to use the solder paste/toaster oven reflow technique.
EDIT 2: One thing I'm a little bit confused about, though, is it mentions setting a certain bit to enable or disable DMA, but I don't see any DRQ pins on the chip... Hmm...
I thought of something that might put a damper on our ethernet fun here...
A block of MAC addresses costs $600.
I suppose you could take your chances generating a random MAC address, or use a MAC address from something else you own that will never be connected to your network again, but we'd need to plunk down that $600 if we wanted to sell any devices with MAC addresses already attached.
If we sell the devices for hobbyist use we would just tell the user not to pick a MAC address that exists on their network already. And that is easy to scan/detect. We're not going into commercial production anytime soon, but if I were independently wealthy that's what I'd be doing.
Alright. Well, in that event, we could probably save a little by having them jumper configured instead of EEPROM-configured, then just have the driver program a MAC address in when it loads.
for what it's worth, andrew lynch, our expert PCB design guy on XTIDE, has whipped up what will likely become XTIDE mkII.
This version includes the "chuck mod" which boosts the R/W performance of the card, has a 32k eeprom, and optionally supports a serial link to allow users to actually boot their PC/XT over serial link hooked up to a modern PC.
We're not going to call it the Chuck mod .. it was no rocket science to figure out that we could be doing 16 bit ops. Besides, I want ours memory mapped. ;-0
The serial port is kind of useless on the Jr - we can't drive *any* UART fast enough with this machine. That's a nice touch, but not terribly usable on a PC/XT class machine.
What about making a small PCB with an edge connector that fits in one of the front cartridge ports with a PIC32 and a USB type A connector. Maybe cut an existing cartridge case down a bit shorter so it doesn't stick out as far then size the PCB to fit. Since the ROM range decode logic is already on the main board, you can just run the address, data, strobes, and chip select lines straight into the PIC32 parallel bus port running in slave mode and serve up a register area, optional full sector buffer, and INT13 handler code all from that ROM slot. Everything you would need is already on the MCU including self booting flash. You would just need a LDO reg, the MCU, and a 24-bit level shifter.
Would allow you to plug a USB thumb drive in for your hard disk. Just a thought.
I would start working on a prototype if I had a ROM cartridge to use as a measurement reference. eBay has been pricely lately on jr stuff. Though I did buy a system unit only for $30 as-is and it booted to BASIC when I plugged it in. yay!
