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DISK EMULATOR OPERATION

GENERAL

The 4C24 has a built in nonvolatile disk emulator with a capacity of up to 2M bytes using EPROM

or 1 M byte using flash EEPROM.

Two 32 pin sockets on the 4C24 can be used for disk emulator memory chips. These two chips can

be used together as a single drive, or each chip can be configured as an independent drive. When two
drives are configured, the chips can be of different types. For example, a configuration with  EPROM
for program storage and flash EEPROM for data logging is a popular arrangement.

When using the built in disk emulator, the disk type configuration jumpers must be first set to

match the type of disk emulator chip(s) used. (See the HARDWARE CONFIGURATION section of
this manual.) 

The 4C24 disk emulator is viewed as a hard disk by system software. This means that the first

emulated drive will be drive C: , and the next emulated drive will be drive D:.

RELIABILITY

In an embedded system environment where a system that won't boot is basically a failed system, it

is important to understand some characteristics of the DOS operating system that applies to disk
access. When DOS writes a file, it writes to the FAT and directory areas of the drive (emulated or
real). 

If there is any chance that a system can be reset or power can fail when writing to this disk, all

information on the disk could become inaccessible, not just the file that was being written. 

The reason is that when DOS writes to a directory or FAT area it always writes a full sector, not

just the directory or FAT entry required. If the sector write is not completed, the sector with the
directory or FAT entry that was being written will have an invalid CRC. This can affect any file on the
drive!

In applications that do frequent disk writes, there are two possible solutions to this problem. The

first solution is to disable emulated disk CRC checking. This will make a partially rewritten sector
readable by the operating system. This will only improve the odds of surviving a power off or reset
during a file write, not totally eliminate the problem. Turning off CRC's will also mask possible
hardware problems, so is not generally suggested. The second solution is to configure a two drive
system, with a drive (usually C:) used as the software drive, and the other drive (usually D:) used as
the data drive. Any files writes during normal operation would be done to the D: drive. If any problem
occurs on the D: drive, software on the C: drive can attempt to recover the data, and then re-initialize
the D: drive.

4C24 TOOL CHIP

An EPROM disk chip preloaded with a set of basic 4C24 utilities is available from MESA at a

nominal charge. If you do not have a PC-104 floppy controller, it is suggested that you purchase this
chip to simplify first time 4C24 setup and disk initialization. 

Page 22

4C24 CPU USER'S MANUAL

Summary of Contents for 4C24

Page 1: ...s reserved This document and the data disclosed herein is not to be reproduced used disclosed in whole or in part to anyone without the written permission of MESA ELECTRONICS Mesa Electronics 4175 Lakeside Drive Suite 100 Richmond CA 94806 1950 Tel 510 223 9272 Fax 510 223 9585 E Mail tech mesanet com Website www mesanet com ...

Page 2: ......

Page 3: ...0 Disk emulator type selection 10 Lithiumcellenable 10 CONNECTORS Power connector 11 Keyboard connector 11 Serialport connectors 12 Parallelport connector 13 CPU OPERATION Power consumption 15 Watchdog timer 15 Serialports 15 Parallelport 15 Other I O 15 Setup storage 16 SET4CSIO 16 Serialfile download 19 Console switching 20 Hard drives 21 4C24 CPU USER S MANUAL ...

Page 4: ...OPERATION General 22 Reliability 22 4C24 ToolChip 22 Disk emulator initialization 23 INSTALLATION General 24 I O connector orientation 24 REFERENCE INFORMATION Specifications 25 Warranty 26 Schematicdiagrams 27 4C24 CPU USER S MANUAL ...

Page 5: ...4C24 CPU USER S MANUAL ...

Page 6: ...ound equipment into which4C24 willbe installed D Ground handling personnelwith conductive bracelet through 1 megohmresistor to ground E Avoid wearing synthetic fabrics particularlyNylon LITHIUM CELL The 4C24 CPU card contains a lithium cell which can create a fire or explosion hazard if improperly handled Do not expose battery to temperatures in excess of 100 degrees Celsius or dispose of in fire ...

Page 7: ... physicalaccess to the 4C24 card The 4C24 BIOS is normally 64K bytes but can be extended to 128K bytes to accommodate Datalight ROM DOS or other built in operating systems On card 4C24 I O includes two RS 232 serial ports a bi directional parallel port and an AT compatible keyboard port The serial interface chips used on the 4C24 are compatible with 16C550A UARTs with16 character receiveand transm...

Page 8: ...ell When the words up and down are used it is assumed that the 4C24 CPU card is oriented with its bus connectors J1 and J2 at the bottom edge ofthe card nearest the person doing the configuration DEFAULT JUMPER SETTINGS Factorydefault 4C24 jumpering is asfollows FUNCTION JUMPER SETTING WatchDog enable W1 UP Watchdog enabled Disk emulator U14 type W2 UP Flash EEPROM Lithium cell connect W8 Disabled...

Page 9: ...CONFIGURATION DEFAULT JUMPER SETTINGS Page 9 4C24 CPU USER S MANUAL ...

Page 10: ... EEPROM disk for data collection If both sockets use the same chip type they can be combined into a single larger disk emulator The 4C24 disk emulator hardware needs to be configured to match the memory type used W2 selectsthe memorytype for socket U14 disk 1 The jumper needs to be set to the up position for flash EEPROM and the down position for EPROM 512K For moreinformation on disk emulator usa...

Page 11: ...lows PIN SIGNAL CURRENT RATING 1 5V 1A 2 GND 1A 3 GND 1A 4 5V 1A The current ratings above meanthat the total 5V current needs to be limited to 2A KEYBOARD CONNECTOR P4 is the AT keyboard reset in and speaker connector P4 is a 10 pin dual row 2mm header The suggested mating connector is Suyin20043 10G2 or 3M 152210 100 GG This is an IDC flat cable type connector A keyboard adapter cableis availabl...

Page 12: ...2 3 second wait for keyboard response to the reset command SERIAL PORT CONNECTOR P2 and P3 are the serial port connectors P2 and P3 are 10 pin dual row 1 headers The suggested mating connector is AMP PN 499934 1 This isan IDC flat cable type connector When the flat cable from P2 or P3 is terminated with a male 9 pin D type connector suggested connector AMP 747306 4 the 9 pin connector will have a ...

Page 13: ...in 9 5 GND Signal ground 10 NC 5V 5V user power or key PARALLEL PORT CONNECTOR The 4C24 has a parallelprinter port The connector for the parallelport uses a 26 pin 2mmheader to save space An adapter widget is available from MESA that converts between the 1mm cable and standard 050 flat cable The 26 pin connector arrangement is such that when terminated with a standard DB25 connector theparallelpor...

Page 14: ...et printer out 7 4 PD2 Data 2 8 17 PSLIN Select printer out 9 5 PD3 Data 3 10 18 GND Ground 11 6 PD4 Data 4 12 19 GND Ground 13 7 PD5 Data 5 14 20 GND Ground 15 8 PD6 Data 6 16 21 GND Ground 17 9 PD7 Data 7 18 22 GND Ground 19 10 PACK Printer Ack in 20 23 GND Ground 21 11 PBUSY Data in in 22 24 GND Ground 23 12 PPE Paper out in 24 25 GND Ground 25 13 PSLCT Printer selected in 26 NC 5V Key Page 14 ...

Page 15: ...event a crashed or otherwise hung system from remaining so indefinitely the 4C24 is provided with a built in watchdog timer that will reset the 4C24 if not fed regularly The time out period of this counter is 1 6 seconds The default INT 1C user tic clock task feeds the watchdog User software must be careful not to disable interrupts for more than these time periods or the watchdog may bite SERIAL ...

Page 16: ...n files loaded with SET4C24 onlyaffect the options specified in the file This makes it possible to separate the configuration files into pieces that only affect a certain aspect of 4C24 operation Note that EEPROM settings do not take effect untilthe 4C24 is reset For more information on setup options you should list the 4C24 CF file in the UTILS directory of the distribution disk This file has all...

Page 17: ... OFF PP MODE UNI DIRECT UNI DIRECT BI DIRECT The PP MODE parameter sets the operational mode of the parallel port The default uni directional mode is the standard printer port mode When set to the bi directional mode bit 5 of the printer control port determines the signal direction on the printer data lines A low on bit 5 sets the lines to theoutput direction a high on bit 5sets the datalines to t...

Page 18: ...d bythe COM3 4 ADDRESS parameter SECSER ADDRESS 2F8 2F8 3F8 COM3 COM4 Sets the address of the secondary serial port The port connected to P3 If set to COM3 or COM4 the addressis determined bytheCOM3 4 ADDRESS parameter PRIMSER ENABLE YES YES NO This parameter enablesor disables the primaryserialport SECSER ENABLE YES YES NO This parameter enablesor disables the secondaryserialport Page 18 4C24 CPU...

Page 19: ...l port is a 9 pin male AT pinout type and that the 4C24 has it s serial port adaptor cable the cable would have 9 pin female connectors at bothends and the following connections 9 pin 9 pin 5 5 ground 2 3 data 3 2 data If your host machine has a 25 pin serial connector the cable needs a female 25 pin connector on the host end and a female 9 pin connector on the client end This cable must have the ...

Page 20: ...ted when the file transfer is complete BR is an optional baud rate parameter IfBR is not supplied RECV uses 9600 baud For example RECV FOO GOO 38400 Q would get the remote file FOO write it to the localfileGOO and abort SEND whendone Alldata transferswould bedone at 38400 baud The remote file name can include a drive and path allowing access to different directories network drives etc If you set t...

Page 21: ...ve This means that no drive parameter information is stored on the 4C24 card This makes it much easier to install and change hard drives It is especially convenient whenusing ATA PCMCIA format removeable drives Hard drives are added to the 4C24 drive list after local flash drives For example ifyou have a two drive flash disk system the flash drives would be assigned letters C and D and the hard dr...

Page 22: ...ormation on the diskcould become inaccessible not just the file that was being written The reason is that when DOS writes to a directory or FAT area it always writes a full sector not just the directory or FAT entry required If the sector write is not completed the sector with the directory or FAT entry that was being written will have an invalid CRC This can affect any file on the drive In applic...

Page 23: ...S format uses 512 byte allocation units and saves space in small drives Do not use the O option with standard DOS or unpredictable file system behavior will result On the 4C24 there are 2 available sockets the upper socket U11 and the lower socket U14 INITRAMD numbers these sockets such that the upper socket is socket 0 and the lower socket is socket 1 Ifyou wanted to initialize a 2 socket disk em...

Page 24: ...lport connector can be cut and a keying plug installed in the cable mount header if desired to prevent reverse installation of the serial cables If more positive polarization is desired on the 10 pin headers center polarized IDC header connectors should be used These connectors will not fullymate with the pins on the 4C24 if installed backwards A suggested center polarized 10 pin IDC header is AMP...

Page 25: ...ply current full speed 486SLC 750 mA Supply current sleep mode 486SLC 150 mA BUS LOADING AND DRIVE Input capacitance 20 pF Input leakage current 5 uA Output drive capability 150 pF Output sink current 6 mA ENVIRONMENTAL Operating temperature range I version 40 85 o C C version 0 70 o C Relative humidity 0 90 Percent Non condensing Page 25 4C24 CPU USER S MANUAL ...

Page 26: ...nt willbe made without charge If the failure has been caused by misuse neglect accident or abnormal conditions ofoperation repairs willbebilled at anominalcost THE FOREGOING WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY FITNESS OR ADEQUACY FOR ANY PARTICULAR PURPOSE OR USE MESA ELECTRONICS SHALL NOT BE LIABLE FOR...

Page 27: ...REFERENCE INFORMATION SCHEMATIC DIAGRAMS Page 27 4C24 CPU USER S MANUAL ...

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