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**82395SX     Smart Cache                                     12/17/90
***Notes:...
**82396SX     Smart Cache                                     12/17/90...
**82485       Turbo Cache (and 485Turbocache)                      c90...
**82489DX       Advanced Programmable Interrupt Controller    10/12/92...
**82495DX/490DX DX CPU-Cache Chip Set                           <Sep91...
**82495XP/490XP Cache Controller / Cache RAM (for i860)       06/05/91...
**82496/491     Cache Controller / Cache RAM (for P5 Pentium) 03/22/93...
**82497/492   Cache Controller / Cache RAM (for P54 Pentium)    <Nov94...
**82498/493   Cache Controller / Cache RAM (for P54 Pentium)    <Nov94...
**
**Later chipsets (basic spec):
**440 series:...
**450NX  (?)            06/29/98:...
**?????  (Profusion)    c:99...
**800 series...
*Headland/G2...
**HT44          Secondary Cache                                c:Jun92
***Info:
The  HT44 is  a  look-aside write-through,  80486SX,  486DX or  486DX2
secondary cache  controller. It is  packaged in an  inexpensive 84-pin
plastic-leaded chip carrier (PLCC).

Architecture
With  its look-aside architecture,  the HT44  fits beside  the CPU-to-
Memory bus  and not in  the data path.   Therefore, once the  HT44 has
been designed  into a  486 system, it  can be populated  for secondary
cache systems or left vacant for non-secondary cache systems. The HT44
is direct-mapped to the available address space.

Performance
The  HT44  has a  number  of  performance  enhancing features.   These
include zero-waitstate burst line fills  to the 486 on secondary cache
hits, and simultaneous 486 and secondary cache updates on read misses.

Memory Configurations
The HT44 supports  cache sizes from 32KBytes to  1MB. Both synchronous
and asynchronous  SRAMs are supported.  25ns SRAMs are  sufficient for
zero-wait-state operation at 33MHz.

Chip Set Support
The HT44 can,  be implemented with minimal glue logic  in a 486 system
with the  HTK340 (code  name Shasta) chip  set.  The registers  in the
HTK340  allow  for programming  of  non-cacheable and  write-protected
areas of  memory. The  HTK340 will support  the HT44  with synchronous
SRAMs only.   Future Headland chip sets will  support both synchronous
and asynchronous SRAM designs.

The HT44  can also be used  with some third-party  chip sets, however,
additional glue logic may be required.

***Versions:...
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*Unresearched:...
*VIA...
*VLSI...
*Western Digital...
*Winbond...
**W83759/A/F/AF   Advanced VL-IDE Disk Controller                  <96
***Notes:...
***Info:
GENERAL DESCRIPTION

The  W83759A  is  an  advanced  version of  Winbond's  popular  VL-IDE
interface chip,  the W83759. The  W83759A retains all of  the features
and  compatibility of  the W83759  (the chip  meets the  ANSI  ATA 4.0
specification  for IDE  hard disk  operation and  the VESA  VL-Bus 2.0
specification  for  PC  local  bus devices)  while  incorporating  new
features  to   meet  Enhanced  IDE,  SFF-8011,   ATA-2,  and  Fast-ATA
specifications.

Supports Disk Capacity of Greater than 528 MB
The W83759A's  driver can handle remapping  from BIOS CHS  mode to HDD
LBA mode.  This scheme  enables users  to break the  528 MB  per drive
barrier, allowing  full use  of BIOS INT13  CHS information  in drives
with a capacity of up to 8.4 GB.

High Speed Host Transfer Rate
The W83759A supports  Enhanced IDE PIO mode 3 and Fast  ATA PIO mode 3
and 4  timing; jumper  settings or driver  programming can be  used to
select  the PIO  mode  and a  33  or 50  MHz  VL-Bus clock.  Different
programming timing  can be selected  for different drives in  the same
system. The burst transfer rate is shown in the following table.

ATA PIO  IDE COMMAND CYCLE  BURST TRANSFER RATE  IORDY THROTTLE 
MODE     TIME (nS)          (MB/sec)             CONTROL
0 	 600  		    3.33 		 Option
1 	 383 		    5.22 		 Option
2 	 240 		    8.33 		 Option
3 	 180 		    11.1 		 Required
4 	 120 		    16.6		 Required

Dual IDE Channels
Like  the  W83759,  the  W83759A  supports  a  secondary  IDE  address
(170h-177h/376h)  and  IRQ15  for  applications with  four  hard  disk
drives.  Additionally,  the  primary  and secondary  channels  can  be
independently  enabled  or disabled  by  jumper  settings or  software
programming.

Non-disk IDE Peripherals
Because  the command  cycle can  be programmed  individually  for each
drive and  dual IDE channels  are supported, non-disk  IDE peripherals
(such  as an  ATAPI  CD-ROM or  tape  drive) can  be  attached to  the
secondary  IDE without  affecting the  transfer rate  of the  ATA disk
drive.  Sales of ATAPI  IDE CD-ROMs  are expected  to grow  rapidly as
these devices become a standard part of many users' desktop PC setup.

The W83759A provides all  of the next-generation ATA-IDE requirements,
including  support for  high  capacity disk  drives,  high speed  host
transfers, multiple IDE peripherals,  and non-disk IDE peripherals. It
makes high-performance, low-cost, easy-to-use IDE machines possible.

The  W83759A is  pin-to-pin backward  compatible with  the  W83759. In
addition  to  the  advanced  features  described  above,  the  W83759A
supports  automatic   power-down,  standby,  and   suspend  APM  power
management states for green PC applications. This new chip is packaged
in a 100-pin QFP.

The table below compares the W83759 and W83759A:

    	  		 W83759     	   W83759A
Dual Channel IDE 	 Yes 		   Yes
8.4 G Max. Cap. 	 Software Driving  Software Driving
PIO Mode 3, 4 Control 	 No 	  	   Yes*
DMA Mode Control 	 No 		   Yes*
IOCHRDY Control 	 No 		   Yes*
IDE Timing Control 	 Jumper 	   Jumper or Driver*
Prefetch Control 	 No 		   Yes*
Power Saving Control 	 No 		   Yes*
ATAPI Protocol 		 Software Driving  Software Driving

>* All control is drive-by-drive (per drive selectability)
***Versions:...
***Features:...
**W83769          Local Bus IDE Solution                           <94...
**
**UARTS:
**W86C250A  UART (equivalent of INS8C250A) [no datasheet]
**W86C450/P Universal Asynchronous Receiver/Transmitter         <Jul89...
**W86C451   I/O controller for IBM PC/AT/XT                     <Jul89...
**W86C452   I/O controller for IBM PC/AT                         Jul89...
**W86C456   I/O controller [no datasheet]                            ?
**W860551/P UART with FIFO and Printer Port Controller             <94...
**
**Other:...
*ZyMOS...
*General Sources:...

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