JJackson%SpaceSys%SwRI15@d15vs178a.space.swri.edu (02/22/91)
Well, I just happened to have the article requested... tried to E-mail
directly... bounced. (I know, you've heard that before)...
***** ATTACHMENT: d:haynie1.txt *****
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga.hardware
Subject: A2630 Daughterboard Information
Message-ID: <9823@cbmvax.commodore.com>
Date: 26 Feb 90 18:23:45 GMT
Reply-To: daveh@cbmvax.cbm.commodore.com (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 293
References:
I've had lots of requests for information on the A2630 Coprocessor Card's
daughterboard connector pinout. Here's the revised version of the bit I
wrote on it for last summer's DevCon. Knowledge of the 68030 CPU bus is
necessary to get much out of this.
-Dave Haynie
---------
THE A2630 DAUGHTERBOARD SPECIFICATION
by Dave Haynie
The A2630 is a basic asynchronous 68030 system running at 25MHz.
The A2630 supports up to 4 megabytes of 32 bit wide memory on-board, similar
in fashion to the A2620 memory. The main difference is that the A2630
on-board memory is always autoconfigured memory; it cannot be relocated even
with some PAL changes.
The A2630 does support 32 bit memory expansion, in the form of a
daughterboard which can contain a considerable amount of 32 bit memory.
The daughterboard is specifically intended for the addition of a single
memory board to the A2630; it is not a general purpose 32 bit expansion bus
of any kind, and should not be expected to exist as-is on future 32 bit
Amiga system. The daughterboard is connected via two 64 pin DIN
connectors, and a mechanical drawing of this connector is suppied in the
appendix.
The pinouts are as follows:
CN300 CN301
1 GND 2 D0 1 GND 2 GND
3 GND 4 D1 3 CPUCLK* 4 CPUCLK
5 GND 6 D2 5 VCC 6 VCC
7 GND 8 D3 7 A0 8 DSACK0*
9 GND 10 D4 9 A1 10 DSACK1*
11 GND 12 D5 11 A2 12 STERM*
13 GND 14 D6 13 A3 14 CBACK*
15 GND 16 D7 15 A4 16 GND
17 GND 18 D8 17 A5 18 BERR*
19 GND 20 D9 19 A6 20 NORAM*
21 GND 22 D10 21 A7 22 GRESET*
23 GND 24 D11 23 A8 24 ECS*
25 GND 26 D12 25 A9 26 GND
27 GND 28 D13 27 A10 28 DBEN*
29 GND 30 D14 29 A11 30 AS*
31 GND 32 D15 31 A12 32 DS*
33 GND 34 D16 33 A13 34 R/W
35 GND 36 D17 35 A14 36 GND
37 GND 38 D18 37 A15 38 SIZ0
39 GND 40 D19 39 A16 40 SIZ1
41 GND 42 D20 41 A17 42 BGACK*
43 GND 44 D21 43 A18 44 GND
45 GND 46 D22 45 A19 46 FC0
47 GND 48 D23 47 A20 48 FC1
49 GND 50 D24 49 A21 50 FC2
51 GND 52 D25 51 A22 52 GND
53 GND 54 D26 53 A23 54 CBREQ*
55 GND 56 D27 55 A24 56 EXTERN*
57 GND 58 D28 57 A25 58 IREFREQ*
59 GND 60 D29 59 VCC 60 VCC
61 GND 62 D30 61 A26 62 EXTSEL
63 GND 64 D31 63 GND 64 GND
NOTE: In the A2630 prototype, the CPUCLK* and EXTSEL pins were reversed. All
production units, however, have the correct pinout shown here.
The signals description follows (note that most of the signals are standard
68030 bus signals, which are more fully described in various Motorola 68030
secifications). Unless otherwise specified, each signal supplied by the
daughterboard should be driven by an F-series or equivalent TTL output, and
each input should present no more than one F-series or equivalent AC or DC
load. As usual, these are the guidelines we're writing the specifications
to; you ignore them at your own risk.
POWER GROUP
VCC This is the +5V supply from the A2630. This supply
has to travel a long way to get here; most daughterboards
will use a different supply (like from a disk drive power
cable) rather than the supplied +5V here.
GND This is the ground in common with the A2630's digital
ground. Grounding is very important for noise immunity!
MEMORY CYCLE GROUP
Most of these signals are used in the basic definition and
qualification of a memory cycle, and can generally change on a cycle by
cycle basis. Some are provided by the 68030/A2630, some by the
daughterboard memory logic.
CPUCLK,CPUCLK* These are the inverted and non-inverted versions of
the clock signal used to drive the 68030, and perhaps the
68882, on the A2630 board. It is recommended that these
be buffered very close to the edge connector of the daughter
board; they are perhaps the most critical signals in the
system.
EXTSEL This is an active-high input to the A2630 indicating
that the daughterboard is responding to the current bus
address. This should be driven based purely on address
(including the address space as specified by the function
codes) and qualifiers such as BGACK*, NORAM*, BERR*, GRESET*,
etc, as appropriate. It should not include any AS* qualifier,
and the maximum address to EXTSEL delay should be no longer
than 10ns for reliable operation. Asserting EXTSEL at the
wrong time (eg, when you're trying to access on-board or
68000 resources) will cause the daughterboard to "overlay"
the other resource. This may actually be the desired effect,
for things such as cache boards.
ECS* This is the 68030 "External Cycle Start" line,
passed unbuffered. Some DRAM refresh arbiters can make use
of this line.
DBEN* This is the 68030 "Data Buffer Enable" line, passed
unbuffered. It may be of use for driving the required data
bus buffers, though as stated by Motorola, it will not be
fast enough for zero wait state synchronous memory cycles.
AS* This is the 68030 "Address Strobe" line, passed
unbuffered. It is the one and only valid indicator of what
constitutes a memory cycle. Note that asserting EXTSEL
will disable the 68000 compatible address strobe that's
normally created by the 68030 for offboard memory cycles.
DS* This is the 68030 "Data Strobe" line, passed
unbuffered. It indicates valid data from the 68030 on a
write, and the earliest that data may be placed on the
data bus during a read.
R/W This is the 68030 "Read/Write" line, passed
unbuffered. It's high for a write, low for a read, just
as you'd expect.
BGACK* This is the 68030 "Bus Grant Acknowledge" line,
which is asserted when an external device has mastered the
A2630 bus. While no DMA is possible to memory boards that
sit outside of the Zorro II/68000 24 bit address space,
daughterboards must still qualify with BGACK* to assure
that an invalid address isn't supplied (since A24 is not
driven by a DMA device).
CBREQ* This is the 68030 "Cache Burst REQuest" line,
passed unbuffered. This is asserted by the 68030 to indicate
that it's capable of a synchronous cache line burst.
CBACK* This is the 68030 "Cache Burst ACKnowledge" line.
This is asserted by the daughterboard in response to a CBREQ*
from the 68030, as outlined by the Motorola documents. This
line should be driven by a tri-state or open collector/drain
output, and left in the appropriate quiescent state when the
daughterboard is not responding to the current address.
IREFREQ* This is a refresh request signal create by the
memory logic on the A2630, and it may optionally be used to
by the refresh logic on the daughterboard. The creation
of this signal is a little weird; it's based on a timer
which runs off the 7MHz A2000 clock, and sampled on the
rising edge of the CPUCLK. It's recommended that the refresh
"go-ahead" signal on any daughterboard DRAM circuitry sample
this on CPUCLK; it's guaranteed to stay valid for at least
one 25MHz clock period, and may actually stay valid for
several.
EXTERN* This is an output from the A2630, used to indicate
that an "external" device is responding to an address. There
are two external devices; the 68882 and the daughterboard.
Asserting EXTSEL will in turn result in EXTERN* being driven
by the A2630 logic. Most daughterboard circuits will not
use this line.
SYSTEM GROUP
These signals are system configuration, startup, or error signals,
and will rarely change. They may have an effect on what's done during a
memory cycle.
NORAM*
This is the direct output of the NORAM* jumper
(J303) on the A2630. It is passed unbuffered.
BERR* This is the 68030 "Bus Error" line, passed
unbuffered. This is used by the A2000 system to indicate
a bus collision of some kind, by the A2630 to generate
F-line exceptions when a math chip isn't present, and by
the MMU to indicate bus faults. The current memory cycle
is aborted when BERR* is asserted.
GRESET* This is a buffered version of the "Global" reset
line, used on the A2630 to indicate a full system reset.
Full system reset occurs on either a power-up or a keyboard-
generated reset. The RESET instruction will not assert.
GRESET*.
BUS SIZING GROUP
These signals, actually an integral part of the memory cycle logic
of any design, are used to match the desired bus size to the actual bus
size. I don't anticipate any daughterboards with anything other than 32
bit ports, but I suppose it's possible.
SIZ0,SIZ1 These are the bus sizing indicators from the 68030,
passed unbuffered. For a memory location to be cachable,
it must always read it's full port size (eg, probably 32
bits), regardless of the state of the sizing bits. For a
write, the size bits are important. This is explained in
detail in Motorola's 68030 documentation.
A0,A1 These are the lowest two address lines, which are
actually more part of the bus sizing mechanism than real
address lines when you're talking about a 32 bit port. As
with the SIZ bits, these are explained fully in the 68030
manual.
DSACK0*,DSACK1* These are the lines used to terminate a 68030
asynchronous cycle; they go directly to the 68030. These
serve to encode the size of the memory port you're dealing
with; the normal 32 bit port will assert both of them. The
minimum asynchronous cycle is three CPUCLKs, or 120ns at
the A2630's standard 25MHz. The 68030 will sample the DSACK
lines on the falling edge of the CPUCLK and latch the data on
a read on the next falling edge. The nice thing about the
asynchronous mode is that you don't have too much worry about
setups and holds -- if both DSACKs miss the sampling edge,
they'll be caught safely on the next sampling edge, just like
on the 68000. Also, the data on a read need only be held
until DS* is negated. These lines should be driven by open
collector/drain or tristate drivers, and left in the quiescent
state when the daughterboard isn't being selected.
STERM* This is the line used to terminate a 68030
synchronous cycle; it goes directly to the 68030. All
synchronous cycles are by convention 32 bits wide. The
minimum synchronous cycle is two CPUCLKs, or 80ns at the
A2630's standard 25MHz. The 68030 will sample the STERM
line on the rising edge of the CPUCLK and latch the data on
the following falling edge. The nice thing about the
synchronous mode is speed -- the basic cycle can go 1 clock
faster, and it can also exploit data cache line burst loads.
However, all signals must be guaranteed stable at their
sampling points within the Motorola specified setup and hold
times, or the 68030 could see some metastability and end up
behaving unexpectedly (eg, you crash or, even worse, mungle
some data). This line should be driven by an open collector,
open drain, or tristate output, and it should be left in the
appropriate quiescent state when the daughterboard isn't
being selected.
BUS GROUP
These are the basic 68030 system buses.
FC(2:0) These are the 68030 function code outputs, passed
unbuffered. Any memory system on a daughterboard must make
sure it ignores any CPU space accesses (FC2:0 = 111) or a
collision between daughterboard memory and the CPU may
take place. It's possible to hook up additional 68030
style coprocessors to the daughterboard bus, bus full bus
decoding is absolutely required. The A2630 uses the two
standard coprocessors, the MMU (number 0) and the FPU
(number 1).
A(26:2) The unbuffered 68030 address bus. As mentioned,
this MUST be buffered, and it's recommended that the buffers
live as close to the daughterboard connector as possible.
Daughterboard memory should not be placed in the $0000000
through $0ffffff range, as that's reserved for main Amiga
resources (of course including A2630 on-board memory).
D(31:0) The unbuffered 68030 data bus. As mentioned, this
MUST be buffered and it's recommended that the buffers
live as close to the daughterboard connector as possible.
--
Dave Haynie Commodore-Amiga (Systems Engineering) "The Crew That Never Rests"
{uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy
Too much of everything is just enougheachus@aries.mitre.org (Robert I. Eachus) (03/14/91)
In article <dhansen.6776@amiganet.chi.il.us> dhansen@amiganet.chi.il.us (Dave Hansen) writes:
Regarding the request for the A2630 daughter board memory expansion,
I can see why Commodore has not considered it a high priority for
manufacturing...If it were possible to break the 9MB addressability
barrier on the A2000, the desirability for additional 32-bit buss
memory would increase...
But the daughter board memory explicitly would be outside the
9MB/16MB memory area! So if anyone does manufacture such a board, I
could add, say another 16 Meg to my 2500/30 without removing any
current memory. (Although I probably would.) With the Toaster
currently shipping only for the 2000 chassis, this would certainly
inspire people to consider the 2630 instead of the GVP boards.
--
Robert I. Eachus
"As far as Saddam Hussein being a great military strategist, he
is neither a strategist, nor is he schooled in the operational arts,
nor is he a tactician, nor is he a general, nor is he as a
soldier...
Other than that he's a great military man. I want you to know that."
-- Gen. H. Norman Schwarzkopf, Saudia Arabia, Feb. 27, 1991