MAR Progress
Starting tonight by wiring up the MAR, I’m going with two 74hc377’s. Why? Because that’s what I’m using. I had some reason, it’s either on a previous day or what someone else used.
Either way, time to hook them up. I had started with the MAR on top of the rom&ram, but I decided to swap that around to hopefully help a bit with the wiring, so I don’t have as many wires crossing over chips. That’ll help with neatness as well. Heh, I need that.
current progress
End of day update. It’s late, I need some sleep, etc
I hooked up the MAR’s 377 outputs to the ram chip, as well as running the common io lines of the ram chip to the right side of that breadboard. I changed my mind a couple times while doing this, the fact that the ram&rom chips are both 3-state certainly helps, so they’re each like buffers.
I don’t have the rom chip yet, it’s supposed to arrive sometime this next week(the 27th), but I’m going to pre-wire it up. I’ve decided to go with 4k rom/28k ram. That technically leaves 32k of space on the table, but I think this is good enough for now. I can always find space somewhere nearby(perhaps on that spare clock board) if I want to add another 32k, but I don’t think I will. 32KB of ram is plenty, especially for a 8/16 bit computer. I think I’ll get rid of the memory LEDs on that breadboard, since that’s now 3-state and not active all the time.
Gn