From f36ce539e38fbfe7de00a7790fb9c9c4a73c9cb2 Mon Sep 17 00:00:00 2001 From: "Curt J. Sampson" Date: Thu, 6 Feb 2020 17:02:06 +0900 Subject: [PATCH] Bus: Pinout and a little description of RC6502 bus --- Bus.md | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 Bus.md diff --git a/Bus.md b/Bus.md new file mode 100644 index 0000000..27fd04d --- /dev/null +++ b/Bus.md @@ -0,0 +1,44 @@ +RC6502 Bus +========== + +The RC6502 system uses a 39-pin bus; the physical layout is a single +row of 0.05" square header pins on 0.1" centers. Conventionally the +boards have a male right-angle connector on one edge and these are +plugged into a [backplane] with female connectors. + +The pinout is as follows. The signal directions (input or output from +the point of view of CPU and peripheral boards, respectively) are +guidelines, and a specific board might have a different direction. For +signals where both are marked `in`, both CPU and peripheral boards are +usually capable of using the signal as an input, but it's expected +that one board in the system will be generating the signal. + + Signal Pin CPU Periph + Name No. Dir. Dir. Notes + -------------------------------------------------------------- + A15 1 out in + … … + A0 16 out in + GND 17 in in + Vcc 18 in in + Φ2out 19 in in + /RESET 20 in in Must be actively controlled by one board + Φ0in 21 in in + /IRQ 22 in in Pull-up req'd; usually provided by CPU board + Φ1out 23 in in Sometimes called EX0 + R/W̅ 24 out in + RDY 25 in out + SYNC 26 out in + D0 27 ↔ ↔ + … … + D7 34 ↔ ↔ + TX 35 ? ? + RX 36 ? ? + /NMI 37 in out Pull-up req'd; usually provided by CPU board + × 38 Also known as EX1 + × 39 Also known as EX2 + + + + +[Backplane]: ./RC6502%20Backplane/