Arbiter and Mode Control

Ogus 416184

Dove Workstation Technical Review - April 9, 1984

Bus Arbiter and Mode Control

• Bus arbitration is needed since there are three external (to lOP 80186) bus masters, viz. rigid disk DMA

controller, Ethernet controller, and PCE 80186

• Bus mode control is needed to switch between the lOP 80186 and the PCE 80186 execution

• Arbitration functions:

Field HOLD requests from rigid disk and Ethernet controllers Determine highest priority device (Ethernet - 1, rigid disk- 2) Pass HOLD request to Mode Control

Pas$ HOLDA from Mode Control to controller being granted the bus Suspend rigid disk DMA acrivity when Ethernet requests service

• Mode control functions:

Determine which of the 80186s should be bus master

Pass HOLD request from Arbiter to current 80186 bus master Pass HOLDA from bus master to Arbiter

lOP to PCE switch is under lOP control (output instruction)

PCE to lOP switch is caused by any interrupt, PCE 1/0 trap, or RESET

ENetHoldReq .... ENetHoldAck ....

,,-

,,-

ARBITRATION

RDCHoldReq .... ^CONTROL

,,-

AllowRDCCmd' ....

RDCHoldAck ....

".

"'i" "'~

NMI .... Stop Ridgid

IntReqPending: Disk DMA

FDCDmaReq ::: ACKNOWLEDGE.. REQUEST

Switch To

:::

ExpDmaReq IOP186

rI"

---

~,.

PCE186 HOLDAck ....

PCElntrIOP' :: PCE186 HOLDReq ....

AllowPCCmd' ~

rI'"

MODE CONTROL IOP186 HOLDAck

"""-

rI'"

IOP186 HOLDReq ....

HoldlOPCmd' ....

rI'"

o

o

o

o

o

MAJOR FLOW CONTROL

Arbitration Control Fields Hold Requests from Ethernet and Ridgid Disk Arbitration Control Generates Hold Request to \'lode Control

]\'lode Control Generates Hold Request to Current 186 Bus Master

Current 186 Bus l\laster :\otifies Mode Control Through Hold Acknowledge

\\[hen Bus l\-'lastership is Treminated

'lode Control Passes Hold Acknowledge to Arbitration Control

Arbitration Control Acknowledges Highest Priority Requesting Oelke Priority # 1 = Ethernet

Priority # 2 = Ridgid Disk

KEY FEATURES

'lODE CO:\TROL

o

When Commanded By AllowPCCmd', Hold IOP186 Then Grant Bus 'Iastership to the PCE186

" Terminate PCE186 Bus \lastership When It Executes an 1/0 Instruction

o

When Commanded By HoldIOPCmd', Hold the IOP186 Until Arbiter :\otification to Release the Hold

.\RBITR.-\ TIO~ CONTROL

o

Terminate Ridgid Disk Bus \Iastership \Vhene\er Ethernet Requests Sen ice

(l

When Commanded By AllowRDCCmd'. Honor Ridgid Disk Hold Requests

(l

When the Following Conditions are True. :\otify the Arbitration Control and \Iode Control

* :\on l\1askable Interrupt

* ^An~' Pending Interrupt

* Floppy Disk Requires DMA Senice

* Expansion Slot Requires 0\1.-\ Senice

"

2

PUe

~IO~P~H~ld~a~T~0~A~r~b

~12~~~~ ~

} o-a-'"

G"1,-!1_.-:.:IO~P~/~P..:C::.:H.:.:I.:::;da~

~12

PCEHlda 13 Ir~~/;; f.a'

~~..:.:::.:::...---..:.:::.V lIel65d

8MHzClk' - 11 LS74

~~~~---~C Q,,~a~ ____ ~IO~P~/~PC~H~ld~a~D~IV~'~

PUe

l3t""

__ ~IO~P~R~e~se~t.:.:ln~' ____ ~

ENetHoldReq 2

+.

-:~~~~~---~D Q~5~~E~N~e~tH~01~d~_

8MHzClk' 3 LS74 1

r---..

~~~~---~C Q,~6~~E~N~e~tH~0~I~d~' ________ ~r-__________________________ ~~ __ ~1~3~ILS2~12 ENetHoldAck

IOPResetln' RstENetCtlr'

+

(Note: if ENet is not installed, keep this signal L to prevent false ENe' bus request),

PUe

ROCHoldAck 14

r1L

....:.;.;.:::.:..:..:::.:..:.;"""-~---"-"'iJ 0 10 OKToAckENet'

~8~M~H~Z~C~lk~' ____________ ~129C. LS109

RDCHold 13 , O'~

....:.;=:.:..:..::~---~ ~ ~' II el5 5 b IOPResetln'

"NOTE:

Once the ROC State sees a true state on the RDCHoldAck line, it MUST BLOCK samples

until the DMA xfer begins.

ENetHold 4

r---..

--':.:..:..::.:..:.;==---"'-OII

LS32 \. 6 ReaRDCToStoD

ENetHoldAck 5 I~"'''''r

L--""~~Q6

~_....:4'-01UII ^{el5 5 b} --':.:..:..::.:..:.;=::..:::.:::!!..----':'..OIL./ II el65 b

PUe

, L

StopRDC' 2 S'

~===;:":::'---'""'"IJ 0 6 R DC Hold

~8~M~H~z~C~lk~' ____________ ....;4~ C LS 1 09 3 0' 7 RDCHold'

r'\r

~R~D~C~H~O~ld~R~eQ~·

~I~ __ ~

(pull down to disable)

AllowRDCCmd'

IOPNMI 4

12

~

o

ChO FDCDmaRea 10 S260 6 StooRDCCond' Ch 1 ExoDmaRea 9

RunRDC' 11 J lIel85b

~8~M~H~Z~C~lk~'~----~~--' 11 LS74

~~~~---~C 0' 8 RunRDC'

~ lIel75b IOPResetln' 13\

~~~~~---~

XEROX

SOD

Dove A rbitration Logic plOP20.sil

9

D!).:8~

~O:.!::K~T~0:!.:R~u~nw:R:"!'O!.lC""'"

~Dlle165 C

Designer Rev Date

R. Knauss A 6/06/84

Page

20

ChO Ch1

XEROX

SDD

All ow PCC d' m

10PNMI IntrReaToArb FDCDmaRea ExoDmaRea RunlOP186 8MHzClk'

10PResetln' PCElntrlOP'

HoldlOPCmd'

IOPNMI Int rReaToA rb FDCDmaRea ExoDmaRea KeeplOPHeld' 8MHzClk'

PCEHldaToA rb

AllowPCCmd'

Project

Dove

1 2 12

3 13

4 8 10

9 11

t

ENetHold' 5.-- RDCHold' 4

4 2 520 6 A rb Hold PCE

2 """'57"' 10PHIdaToA rb

5260 5 10PWantBus' RunPCE1B6

1 U#dZ76a

o

#ef85a

3 574

I ,r-

9

508 8 ModeReset' 100 #e165c

10 5260' 6 GiveUolOPHold' 12 '"'""'S'":-

#ef85b

o ofi

---?.~

574 IOPHeld'

11 508 6

I

t

10PResetln'

13.-- ENetHold' 12

1 RDCHold' 10 520 8 ArbHoldlOP

LS32 11 PCEHlda 9U#CZ76b

13

#ef65d

PUe "NOTE:

L4-

the PCE reset is released before the AllowPCCmd' is executed. If

o ofi

3 L574 the arbiter WILL FAIL to function

PCHack properly.

C _Q' 6 10PResetln'

+

File Designer Rev Date Page

Mode Control Logic plOP21.sil R. Knauss A 6/04/84 21