What's with the 486 DLC Cyrix stuff?
John Neuharth
Can someone give me a little detail on the 486-DLC relative to the
SX and DX? Thanks!
-John Neuharth
jp...@news.delphi.com
>-John Neuharth
YES!!! Tell me too! Thanks in advance...
Wayne Schlitt
>
> Okay, I'm still checking out 486 motherboards...
>
> Can someone give me a little detail on the 486-DLC relative to the
> SX and DX? Thanks!
>
Ok, briefly, here are the major differences :
* the 486DLC is made by Cyrix (or TI as a subcontractor) not Intel
* like the Intel 486SX, the 486DLC does not have a floating point
coprocessor.
* the 486DLC only has a 1k cache and is only 2-way set associative vs.
the Intel's 8k.
* the 486DLC uses the 386DX pinouts/bus. This bus lacks the burst
mode cache line refill, so it is slightly slower than the 486's bus.
* the 486DLC _does_ implement the extra 6 instructions that were added
by Intel to the 486 vs the 386. There are some _very_ minor
differences in how the system handles exceptional conditions, but
for the most part, you are very unlikely to notice any differences
for a genuine Intel chip.
* the 486DLC uses a 387 type coprocessor, of which Cyrix also makes
and often package with the 486DLC for a total price that is lower
than an Intel 486DX (and much cheaper than the 487). On the other
hand, since the FPU is a separate chip, it has to use an external
bus and therefor is slower.
The net result is that the 486DLC is going to be slower than a 486DX,
buy about 10-25%. It will also be cheaper. (if it isn't, then don't
bother with it.) The $64,000 question is, is it worth it to you to
have a slower processor for less money, or a faster processor for more
money.
-wayne
--
The Average Person's Axioms of First Order Predicate Logic:
(A => B) => (B => A)
(There exists) x A(x) => (For all) x A(x)
(A => C) & (B => C) => (A => B) --Warren Vonroeschlaub
M. Yoshida
>.
Read July's PC Magazine about the Perfect PC.
M. Yoshida
>.
IBM made 486SLC2-66Mhz motherboard is about $20-30 more than Cyrix's
486DLC-33, but it is fast. It is faster than Dell/Compaq's 486DX-33
(but slower than i486DX2-66). Here is the Landmark results:
CPU: 151.69
FPU: 185.91
Also, the board has three year warranty directly from IBM.
Siew Chan
>>Okay, I'm still checking out 486 motherboards...
>>Can someone give me a little detail on the 486-DLC relative to the
>>SX and DX? Thanks!
>>-John Neuharth
>>neuh...@u.washington.edu
> YES!!! Tell me too! Thanks in advance...
> jp...@delphi.com
Okay everyone,
The Cyrix 486DLC is pin-compat. to the Intel's (and AMD's) 386DX chip.
So, you should be able to pull the 386DX out and plug in the 486DLC. The
following I'm not too sure, but I think it's correct - your BIOS must
support the Cyrix to make use of its caching instruction set, or
alternatively, a device driver may be loaded or a program may be
executed to use those instructions (think these are ftp-able).
The Cyrix 486DLC has a 1K internal cache and can execute 486 instruction
code. It has no math-co built-in but I think most retailers tend to sell
the DLC with a Cyrix math-co (well, most retailers in Western Australia).
I have seen reports that the DLC-33 is *ON AVERAGE* 75% the speed of the
Intel 486DX-33. My friend's DLC-40 runs Linux faster than a 486DX-33.
Think that's enough for the moment...
Sean
ric...@tartarus.uwa.edu.au
P.S. the Cyrix 486SLC is pin-compat. to the 386SX
Wayne Smith
>
>IBM made 486SLC2-66Mhz motherboard is about $20-30 more than Cyrix's
>486DLC-33, but it is fast. It is faster than Dell/Compaq's 486DX-33
>(but slower than i486DX2-66). Here is the Landmark results:
>
>CPU: 151.69
>FPU: 185.91
>
>Also, the board has three year warranty directly from IBM.
Ok, so where can I buy IBM's motherboard? Does it come with a 487-
equivalent math co-pro and 256k on-board cache ram? Does it cost $30
more than the $250 486DLC-40 motherboard that I'm soon going to buy?
Rick Chow
:
: Ok, briefly, here are the major differences :
:
: ...[stuff deleted]...
:
: * the 486DLC uses the 386DX pinouts/bus. This bus lacks the burst
: mode cache line refill, so it is slightly slower than the 486's bus.
: ...[stuff deleted]...
I found the following from the Sept 92 issue of Computer Shopper (p.76)
and I quote:
"The primary difference between the 386 and the 486 buses is that the 486
bus can perform burst transfers, reading four successive memory locations
quickly to fill a small section of the cache. This is more efficient than
performing four individual reads, as the 386DX bus requires."
Is this the same as what Wayne Schlitt mentioned in his post?
Does it mean the Cyrix DLC-33 and 40 motherboards are essentially 386
motherboards?
--
____
|||||| WYPIWYG (What You Pay Is What You Get)
O .. O Rick Chow
\/ c...@cacs.usl.edu
Wayne Schlitt
>
> wa...@backbone.uucp (Wayne Schlitt) writes:
> :
> : Ok, briefly, here are the major differences :
> :
> : mode cache line refill, so it is slightly slower than the 486's bus.
>
> and I quote:
>
>
> Is this the same as what Wayne Schlitt mentioned in his post?
yes.
> Does it mean the Cyrix DLC-33 and 40 motherboards are essentially 386
> motherboards?
Yes, although there can be a couple of addition pins that help with
cache coherency. The older 386 chip sets don't inform the CPU when a
DMA device updates memory since the 386 doesn't need to know. This
logic isn't hard to add since the chip sets have to invalidate the off
chip cache too...
Without this extra info, the Cyrix chip has to invalidate the entire
cache when DMA is going on. For single user, DOS type systems with
IDE drives, this isn't much of a problem, but if you are using UNIX,
OS/2 or WNT, and you have a SCSI drive this can be a real performance
hit.
Bruce Bowen
Here's some information I retrieved from Cyrix's BBS (214) 680-3187.
They also have an automated "Faxbak" service (800) 462-9749.
Msg#: 58 *Processors*
07-19-93 12:10:00
From: SYSOP
To: RANDALL W RACKOV (Rcvd)
Subj: REPLY TO MSG# 53 (SOFTWARE FOR 486DLC33)
Randall, in order for your DLC to work properly, the cache must be turned on.
That is the reason that the DLC was an OEM device that we sent to Mboard
manufacturers who modified their 386DX mboards with the proper circuitry as
well as a change in the BIOS to turn on the 1K cache on the DLC. Without the
Cache being turned on you will not have the performance designed into the DLC.
Some vendors have gotten hold of our chip and are packing it with S/W to turn
on the Cache. We don't support the DLC being used in this fashion. When
implemented properly, the DLC performs quite well. Thanks for calling Cyrix.
Msg#: 127 *Processors*
08-17-93 10:51:01
From: SYSOP
To: JOHN D. STOCKTON (Rcvd)
Subj: REPLY TO MSG# 118 (486DLC IN 386DX MOTHER PCB)
John, I think I will take you on a brief history of our CX-486DLC product. The
DLC is an OEM(manufacturing) product for us. We worked with System Board
manufacturers who modified their 386DX mother boards in order to be compatible
with the DLC. The modifications required were two. First, there had to be
additional circuitry hardwired to the board itself. Second, there had to be a
change in the BIOS to support the 1K internal cache on the DLC. When
implemented on a Cyrix Ready board, this is a real performer. We never
intended or advertised the DLC as a retail upgrade product for existing 386
systems. It will not work because there is no way to turn on the cache. Some
mboard manufacturers are trying to get by with just changing out the BIOS.
That is not enough. Some vendors have acquired our chip from who knows where,
and are selling it with software to turn on the cache. We didn't write the
software, and we don't support the use of the DLC in this way. However, there
is nothing we can do to keep this from happening. For people who have found
themselves in this situation, we have offered a cache coherency socket and a
software driver for about $130 to help them out. Our upgrade chip which is the
CX-486DRX2 is a clock doubled direct replacement upgrade for 386DX 16,20, and
25MHz PCs. We will eventually have a 33 MHz. It's Cache is enabled through
the use of a Software driver that comes with it. This must be done, because the
cache cannot be enabled any other way. I hope this answers all of your
questions. Thanks for calling CYRIX!
*************************************************************************
CYRIX 386 to 486
UPGRADE MICROPROCESSOR
Information Sheet
I) Product Description
The Cyrix 386 to 486 Upgrade Microprocessor is the only single
chip microprocessor upgrade designed for 386DX-16, 20 or 25 MHz
computers. It is based on Cyrix 486 technology and features clock doubling,
a 1K on chip cache, Cyrix cache coherency technology (patent pending),
fast I/O and a clock skewing correction circuit. The result of these features
are the benefits of compatibility, data integrity and high performance.
II) Key Features and Benefits
Single Chip Design
Direct microprocessor upgrade. High quality, dependability and no
space problems.
Supports 486 Instruction Set
Runs all of today's and tomorrow's 386 and 486 software.
Clock Doubling
Enhanced performance with the Upgrade Microprocessor running at
twice the computer's bus clock speed.
On Chip 1K Cache with Cache Coherency Support (patent pending)
High performance with data integrity
Fast I/O
High performance from improved input/output operations of data
between the microprocessor and the computer's bus.
Clock Skewing Correction Circuit
Ensures compatibility with systems whose internal clock may be
variable.
Supports DOS, Windows and OS/2 Operating Systems
Universal Software Compatibility.
Easy installation
No additional system modifications.
III) Implementation of Key Features
1) Single Chip Design - The Upgrade Microprocessor comes in a
single chip form factor the same size as the 386DX microprocessor. This
single chip design ensures long term reliability and eliminates any
physical space problems found with board style upgrades.
2) Supports 486 Instruction Set - Based on Cyrix's Cx486 design,
the Upgrade Microprocessor will support all 386 and 486 software applica-
tions available today. This also ensures compatibility for all future
software designed under 386 and 486 industry standards.
3) Clock Doubling - Clock doubling greatly enhances performance
of all applications, particularly those applications that are processor
intensive. The Upgrade Microprocessor will run at a speed twice that of
the 386DX microprocessor. For example, if the 386DX microprocessor being
upgraded runs at 20MHz, the Upgrade Microprocessor will run at twice the
speed, or 40MHz. Since the system's clock is not adjusted or changed, no
additional FCC approval is required for the Upgrade Microprocessor.
4) On Chip 1K Cache - Significant performance gains are achieved
withthe Upgrade Microprocessor's on chip cache. This cache is a memory
areawithin the Upgrade Microprocessor that holds data ready to be used by
the processor. Since this data is in the processor, it can be accessed more
quickly than retrieving from the system's memory. This feature is not found
in 386DX microprocessors.
5) Cache Coherency - Data integrity is assured with Cyrix's cache
coherency technology (patent pending). Since 386 systems are not designed
to support an on chip cache, this technology ensures data integrity between
the internal cache and external memory.
6) Fast I/O - This is an enhanced feature Cyrix has incorporated into
the Upgrade Microprocessor which is not found in other 386 and 486 micro-
processors. This feature allows the processor to continue processing during
input/output functions to other components of the computer like printer ports,
disk drives and graphic boards. Fast I/O will significantly improve video and
disk performance where many I/O functions take place.
7) Clock Skewing Correction - This feature ensures compatibility
where other upgrade products do not. Since tolerances vary with many 386
computer system clocks, Cyrix has implemented in the Upgrade Microprocessor
this mechanism allowing it to adjust to system clock variances.
8) Supports DOS, Windows and OS/2 - We said earlier that 386 systems
do not support an on chip cache as found in the Upgrade Microprocessor. In
order to turn on the cache a small program is automatically run when booting
up the PC when the upgrade installed. This program is included with the
upgrade package on 3.5" and 5.25" diskettes along with easy to follow steps
for installing the software onto your hard drive while running either DOS,
OS/2 or Windows. The cache software will run each time the computer is booted an
d since it simply turns the cache on it does not stay
resident. It does not interfere with any operating system functions or
applications the user will be running.
10) Easy Installation - Since the Cyrix 386 to 486 Upgrade Micro-
processor solution is a single chip and there are no BIOS or other system
modifications needed, installation is easy and straight forward. Installing
the upgrade requires three steps: 1) Remove the 386DX microprocessor,
2) Insert the Cyrix Cx486DRx2 processor into the microprocessor socket and
3) Install the cache software.
IV) Difference between a 386 and a 486 Computers
The viability of upgrading a 386 computer to a 486 by using the
Upgrade Microprocessor can best be understood if we take a look at the real
differences between the two types of systems:
COMPONENT 386 COMPUTER 486 COMPUTER
Microprocessor 386DX/SX 486DX/SX
>>>>>>>>>> Supports 386 Supports 486
>>>>>>>>>> Instruction Set Instruction Set
Graphics VGA Standard VGA Standard
>>>>>>>>>> Super VGA Available Super VGA Available
Disk Drive IDE Interface IDE Interface
>>>>>>>>>> Multiple Drives Multiple Drives
Memory SIMM Device SIMM Device
>>>>>>>>>> Expandable to 12MB Expandable to 16MB
From the above chart we can see that both 386 and 486 computers
use VGA as the graphics standard, expandable SIMM memory, and an IDE drive
interface supporting multiple drives. The major difference is the micro-
processor.
In the past, as each new generation of processor became available
the only path for taking advantage of new processor technology was to pur-
chase a new computer. This was true because of the major differences between
8088, 286 and 386 systems in terms of design, graphics, memory and disk
interfaces.
The key point with Cyrix's Cx486DRx2 Upgrade Microprocessor is that
it upgrades the main difference between a 386 and 486 computer; the micro-
processor.
V) Compatibility
The Cyrix Upgrade Microprocessor has been tested in numerous PCs for
compatibility including systems from IBM, Compaq, AST, Everex, Dell and
Toshiba. There have been only a few systems that have not tested compatible.
The following systems have exhibited an incompatibility with Upgrade
Microprocessor:
- AT&T/Olivetti 386DX-16 & 20MHz systems
- Sun i386 systems
- Memorex 386 systems
The IBM PS/2 Model 70/16MHz has tested compatible but the Upgrade
Microprocessor requires the system to have 85ns memory installed. The system
originally came from IBM standard with 2MB of 85ns memory. IBM's specifi-
cation on additional memory called for 85ns memory. Unfortunately, a number
of systems upgraded beyond the initial 2MB were upgrade with slower 100ns
memory. Although this generally does not cause problems in the Model 70,
when upgrading to a faster microprocessor the system will need all memory
to be 85ns. This requirement only affects the 16MHz model.
A small number of the early Compaq Deskpro 386/16MHz came with a
287 math coprocessor socket instead of the standard 386 math coprocessor.
Installation of the Upgrade Microprocessor will require the removal of any
287 math coprocessor installed in the system.
VI) Packaging
The Cyrix Upgrade Microprocessor comes in a single package containing the
following items:
* Cx486DRx2 microprocessor chip
* Installation Manual
* Pair of 386DX microprocessor removal tools
* Upgrade Cache installation disks (3.5" & 5.25")
* Pin 1 locator arrow *
* Heat sink (required for 20/40 and 25/50)
* Warranty Registration Card
* The pin 1 locator arrow aids in the ability of properly orienting
the Upgrade Microprocessor correctly in the socket.
CRC%...@kriski.zer
:
: Ok, briefly, here are the major differences :
:
:
: * the 486DLC uses the 386DX pinouts/bus. This bus lacks the burst
: mode cache line refill, so it is slightly slower than the 486's bus.
: ...[stuff deleted]...
I found the following from the Sept 92 issue of Computer Shopper (p.76)
and I quote:
"The primary difference between the 386 and the 486 buses is that the 486
bus can perform burst transfers, reading four successive memory locations
quickly to fill a small section of the cache. This is more efficient than
performing four individual reads, as the 386DX bus requires."
Is this the same as what Wayne Schlitt mentioned in his post?
Does it mean the Cyrix DLC-33 and 40 motherboards are essentially 386
motherboards?
--
WAYNE%B...@kriski.zer
> :
> : Ok, briefly, here are the major differences :
> :
> : mode cache line refill, so it is slightly slower than the 486's bus.
>
> and I quote:
>
>
> Is this the same as what Wayne Schlitt mentioned in his post?
yes.
> Does it mean the Cyrix DLC-33 and 40 motherboards are essentially 386
> motherboards?
Yes, although there can be a couple of addition pins that help with
Pete Holsberg
>Subject: Re: What's with the 486 DLC Cyrix stuff?
>Date: Wed, 25 Aug 1993 01:11:32 GMT
>In article <1993Aug24.1...@usl.edu> c...@cacs.usl.edu (Rick Chow) writes:
>>
>> wa...@backbone.uucp (Wayne Schlitt) writes:
>> :
>> : Ok, briefly, here are the major differences :
>> :
>> : * the 486DLC uses the 386DX pinouts/bus. This bus lacks the burst
>> : mode cache line refill, so it is slightly slower than the 486's bus.
>>
>> I found the following from the Sept 92 issue of Computer Shopper (p.76)
>> and I quote:
>>
>> [ ... ]
>>
>> Is this the same as what Wayne Schlitt mentioned in his post?
>yes.
>> Does it mean the Cyrix DLC-33 and 40 motherboards are essentially 386
>> motherboards?
>Yes, although there can be a couple of addition pins that help with
>cache coherency.
What's the speed/performance relative to a 486DX/33?