File ctrlnet.txt, 19/10/95.

HP-PC Interface Control Net names and use
-----------------------------------------


Early Inputs To Control State Machine
=====================================
FRR		Fifo Reset Request
SRR		Status Report Request
SPCHPF		Set PC to HP (ie: status) Flag line
IMBF		Input Mailbox Full
OMBF		Output Mail Box Full
HBYTE		Byte 1 or 3 is in Input Mailbox if the word is a data word
		  otherwise the bit is don't care.
TAG[1:0]	0X -> Command Word, 10 -> Low Data Word, 11 -> High Data Word	
FF		Fifo Full
FE		Fifo Empty

Late Inputs To Control State Machine
====================================

SMP[2:0]	State Machine Parameters 

	Coding : SMP2  SMP1  SMP0    FUNCTION
        ---------------------------------------------------------------
		  1     1     1      Reset Fifo
		  1	1     0	     Send Bios Report Code
		  1	0     1	     Read FIFO to OMB
		  1     0     0      HP1000 data transfer
		  0     1     1      Not Used
		  0     1     0      Not Used
		  0     0     1	     Not Used
		  0     0     0      IDLE

Outputs From Control State Machine
==================================
BROMS		Build Register Output Side Multiplexer Select
BRIMS		Build Register Input Side Multiplexer Select
BRCE0		Build Register Clock Enable 0 (Low Byte)
BRCE1		Build Register Clock Enable 1 (High Byte & Tag)
CR		Command Reset
PCCR		PC Command Reset
BRTE		Bios Report Code Transfer Enable
MASEL		FIFO Address Multiplexer select line
FRCCE		FIFO Read Counter Clock Enable
FWCCE		FIFO Write Counter Clock Enable
FSCCE		FIFO Status Counter Clock Enable. This line is created by
		   ORing FRCCE & FWCCE at the Prom Output since Writing and
		   Reading the Fifo modifies the Fifo Status Counter. 
FSCUP		FIFO Status Counter Up/-Down
RDBOEL		Output enable (act. low) for the buffers driving the external Ram Data Bus
OMBCE		Output Mailbox Clock Enable
IMBRR		Input Mailbox Ready Reset
FR		Fifo Reset. This line is created by ANDing FRCCE & FWCCE at the Prom Output
		   since Writing and Reading the Fifo at the same time is meaningless.
PCHPLE		PC->HP Status Latch Enable
HPPCOE		HP->PC Data Buffer Enable
RCEL		RAM Chip Enable Active Low
WEL		RAM Write Enable Active Low