Mike's PCjr Page

If you wanted to give this a shot, I'll have a few devices in DIP packages here next week. Device simulators are great, but I don't really trust things until I get them on a board under a scope. So I can do that next week.

I took a quick stab at translating the schematic logic into WinCUPL HDL. As I was doing it, it occurred to me more than once that this is pretty complex for the simplistic product terms in a 22V10 but it didn't complain when I compiled and it did produce a JEDEC file. So I'll try and program a device next week and test. I know it will fit in an ATF750 but that's twice the cost (but pin compatible).

If there was going to be a one or two off proto build from wire wrap or jumpers, maybe it could be co-routed for both designs.

Lutiana wrote:Okay, so my understanding is that if we use these chips (they essentially PLCs right?) then we open up a ton of space on the board. Does this mean we can add a RTC now?

I am thinking, an IDE/RAM/RTC card would be a one stop sidecar for most, I know I would be completely set with those 3. We can just make a jumper block to enable/disable any of the 3, so people could configure the sidecar as they need it.

Yeah, I've investigated the idea of putting an RTC in. It's definitely doable, but it's something we'll need to write out own drivers for (which I might actually be able to do, after figuring out how to interface with the clock in the Booster).

Personally, it's not an issue for me to loose the Booster clock anymore, as I got Maxim to send me a couple free samples of the DS1216E (one of which is now sitting comfortably in one of my system ROM sockets).

Well guys, I just submitted another sample request to Maxim, this time for the DS1511Y+. That might be a good choice for a sidecar based RTC.

Ouch! $24.

alanh wrote:Ouch! $24.

I know, the price is terrible. If I can get a free sample, though, I'm gonna try to work with it.

I believe there are somewhat compatible cheaper RTC chips out there, though.

EDIT: Jameco has it for a little under $19.

http://www.jameco.com/webapp/wcs/stores ... 1195111_-1

I put a RTC on my ISA prototype carrier boards to evaluate and spent about $2 total not including a 2032 battery. But it was SMD. Maxim/Dallas is proud of their stuff.

Ha, yeah. Well, the chips that are multiplexed for data and address are a lot cheaper, as are the chips that aren't multiplexed but only have a 4-bit data bus. At any rate, it doesn't hurt me to get some free samples.

Here's one of the 4-bit chips I was talking about:

http://www.jameco.com/webapp/wcs/stores ... SF&CID=GMC

Alright, Alan, here's a schematic with your 22V10 in it - I'm hoping I got it hooked up in the way you intended. The symbol I found included the wrong configuration of pinout for the way you have it set up, but I haven't changed it yet.

What do you mean wrong pin out? Pin 12 is GND, 24 is +5V, 1-11 & 13 are inputs only and the rest inputs or outputs. Signal assignments are made by pin number in the code. BTW when you start routing, you can move any Pin-I/O assignment around within those constraints and then change it in the PLD file. Can often save a via or two or three...

I didn't get a chance to order samples yesterday, but I will today. I just want to wire up the circuit as it exists on XT-IDE mkII vs a PAL and truth test both with a MCU and check propagation times etc under a scope first. Should be done with that by next weekend.