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PowerSOFT Products 11500 Stemmons Expressway, Suite 125 Dallas TX 75229 (214) 484-2976 |
| The Model 4/4P computer has the capability of running in two modes: Model III mode and Model 4 mode. This allows a Model 4/4P owner to use two (or more) different operating operating systems on the computer. Two operating systems, one for each mode of operation, are available from Radio Shack for use on the Model 4/4P with a Radio Shack 5-megabyte hard drive: TRSDOS 6 for Model 4 mode, and LDOS 5.1 for Model III mode. The question has arisen among users of the 5-megabyte hard drive of whether there is any way to use both operating systems on the same hard drive without having to reformat and recreate the system partition every time. There is some justification for wanting to do this. The two operating systems involved, LDOS 5.1 for the Model III mode and TRSDOS 6.1 for the Model 4 mode, are very similar. Moreover, since the software base for TRSDOS 6 is not yet as large as that for LDOS, it can be to a user's advantage to switch to LDOS to run applications which are not available for TRSDOS 6. Finally, a hard drive system provides extensive storage capacity as well as increased operating speed over floppy disks. It seems a waste to have to switch to floppies just to run a particular application. |
| We at PowerSOFT have been able to place both the LDOS and TRSDOS 6 operating systems on a single hard drive so that they can be used by a Model 4 running in either mode. The selection of which system to utilize is done by simply booting up the appropriate floppy system disk and letting the configuration file transfer control to the hard disk. The files on the hard disk are accessible to both operating systems. This was made possible by the media compatibility which exists between LDOS and TRSDOS 6. This means that they can read each other's directories and disk formats without requiring special software. |
| The key to placing both operating systems on a single hard drive lies in the flexibility of the two operating systems. Both LDOS and TRSDOS 6 allow you to split up a hard drive into one or more logical drives; and the logical drive numbers need not be the same as the physical positions of the hard disk partitions. This is what makes it all work. The hard disk partition which is assigned as Drive 0 for LDOS need not be the same as the partition which is assigned as Drive 0 for TRSDOS 6! This means that TWO independent logical drive zeros (system drives) can exist on a single hard drive, one for each operating system. And of course, each operating system sees only its own drive 0, the other one appearing to it as something else. |
| Once this concept is understood, the application of it is quite simple. |
| Consider the setup of a 5-megabyte hard drive system. Each hard drive contains two disks or platters, each with two surfaces (four surfaces in all). Each surface has its own read/write head. Both LDOS and TRSDOS 6 allow us to split the hard drive along the surfaces (sometimes referred to as the "head offset method," head referring to the individual read/write head of each surface). This means that we can split a hard drive into a maximum of four logical drives, assigning one surface ("head") to each. This is what happens when we execute the Model 4 hard disk initialization program. The hard disk is split into four logical drives, the first surface being drive :0, the second drive :1, the third drive :2, and the fourth drive :3. |
| There is nothing in either operating system which says that Surface Number One must be logical drive 0 always. So what we can now do is run a modifiedinitialization file under LDOS that reverses the order of logical drives :0 and :3.That is, surface four becomes drive :0, and surface number one becomes drive :3. Thuswe can have two different drive zeros on the hard drive. But the drive :0 which isthe system drive when TRSDOS 6 is running is drive :3 when LDOS running and viceversa. Voila, we have two operating systems sharing the same hard drive! And sinceonly one operating system can be running at any one time, there is no conflictbetween them. Consider the diagram below. |
TRSDOS 6 sees ==> :0 :1 2 :3
PHYSICAL SURFACE 1 2 3 4
LDOS 5.1 sees ==> :3 :1 :2 :0
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| Of course, it falls on the user of such a shared system to make sure thatprograms which run only under one operating system or the other are clearly andobviously marked. One way to accomplish this is to place model- specific programfiles on each operating system's respective drive 0, and have data files (which canusually be read by both systems) resident on the other two logical drives. Or filescan be renamed so that those intended for LDOS (Model III mode) only end with "M3"while those intended for TRSDOS 6 (Model 4 mode) only end with "M4." There are many possible schemes to choose from and you should select one which suits your particularsituation best. |
| We present below a three-step procedure to implement the method just described, for those Model 4 hard drive owners who wish to use both LDOS and TRSDOS. Please makesure that you backup EVERY file on your hard drive before you implement this procedu re, as the hard drive will be reformatted. |
| To use this procedure, you must have both the TRSDOS 6 hard drive initialization disk as well as the LDOS hard drive initialization disk available. |
| STEP ONE. Boot up your TRSDOS 6 Hard Drive Initialization Disk. This will automa tically execute the initialization program. Follow the steps described in your Hard Disk Startup Manual. Tell the program that you to create a hard drive system with eq ual partition sizes, the hard disk to be the system device, and the hard disk to be s earched FIRST when looking for a file. This will result in the hard drive logical dr ive numbers as 0, 1, 2, and 3. Proceed to format the hard drive, move files over to it, and create your BOOT diskette. These procedures are all described in the Hard Di sk Startup Manual. |
| STEP TWO. Make a BACKUP of your LDOS Hard Drive Initialization disk. Boot up thi s disk but do NOT execute the initialization procedure yet. We must modify the Model III Hard Disk Initialization files, using the PATCH command of LDOS. First type: BU ILD INITHD3/FIX. Then type in the patch lines below EXACTLY. |
.Patch to INITHD3/JCL to reverse head order and skip
.FORMAT
D09,B8="1"
D09,EB="4"
D0E,6F="."
D0E,9C="."
D0E,C9="."
.End of Patch.
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| Now press BREAK. The patch file will be written to disk. Now type: PATCH INITHD3/JCL USING INITHD3/FIX and press ENTER. The patch will be applied to the INITHD3/JCL file. There is one more patch which needs to be applied. Since it is very short, you will not build a separate patch file for it, but simply type it in on the command line. Type: |
PATCH HD1/CFG.CCC (D02,F7=13:D03,15=10)
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| And press ENTER. The patch will be applied to HD1/CFG. |
| You have just patched the LDOS Hard Disk Initialization files to (a) reverse the order of logical drives :0 and :3 on the hard disk, and (b) skip the formatting process (since we've already formatted the hard drive under TRSDOS 6). |
| STEP THREE. Execute the patched LDOS (Model III) Hard Disk Initialization with the command, |
DO INITHD3 (NEW,PW=PASSWORD,HARD1,FLOPPY2,ABS) |
| Refer to the Model III Hard Disk Startup Manual, page 31 and following, for more details. |
| You now have a hard drive shared between LDOS and TRSDOS 6. Selection is automatic depending on which boot disk is in the floppy drive when the reset button is pressed. When you are running TRSDOS 6, you will note that your logical drive :3 has the LDOS system files on it. When running LDOS in Model III mode, logical drive :3 will have the TRSDOS 6 system files on it. Logical drives :1 and :2 will be the same regardless of which operating system is currently running. This way, any programs which reference files on these two logical drives will not need to be changed. |
| Using this method, you will be able to use a Model 4 or 4P system with a hard disk to its maximum capability, rather than having to use one operating system on a hard disk and the other on floppies (or on another hard disk). The same method works on larger-capacity hard drives as well, if you have them hooked up to a Model 4 or 4P computer. Unfortunately this method is not usable with CP/M Plus, since CP/M Plus does not have the capability of splitting a hard drive into several logical drives; it sees a hard drive as a single volume only. |
| The same technique is used to create different system partitions that will be used by two or more computers in a multiplexed situation. In this type of environment, several computers share the same hard drive, and the hard drive is split up so that each computer has its own system partition. These system partitions may be set up so that they are invisible to the other computers, in order to prevent accidental alteration of the system files. In order to maximize the use of available storage space, a hard disk driver program which permits a type of partitioning known as cylinder offset is preferable. Using such a driver, the size of the system partitions can be limited to the minimum necessary to hold the operating system modules and a few often-used (and machine-specific) utilities, leaving the rest as sharable storage between the various computers. |
| If you have a hard drive which uses a Western Digital controller board, contact PowerSOFT at the address above for more information on hard disk drivers and other hard drive utility software. |
by Michael Cooper
| One of the features of LDOS that make it a superior operating system is the device independence. This allows you total flexibility in the way you can set up the system I/O. In the case of CLUB-80 I needed to include a communications link to the operating system, but still protect the integrity of the applications programs and files. |
| The Standard Devices in LDOS are : |
*KI = Keyboard
*DO = Video Display
*PR = Printer
*SI = System Input (Unassigned)
*SO = System Output (Unassigned)
*JL = Job-log (Unassigned)
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| LDOS comes supplied with a Serial Device Driver for use with the RS-232 Port.The Model 3 version of the driver(RS232T/DVR) is very sophisticated, with an input buffer of 128 bytes and interrupt handling of incoming characters. To set the driver for use with a MODEM you must specify the Baud Rate and Byte configuration. |
SET *CL TO RS232T (B=300,W=8,S=1,P=N,DTR,RTS)
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| This will create a new device called *CL- Comm Line that uses RS232T as its driver program. The parameters passed in the parentheses set Baud Rate = 300, Word length = 8 Bits, Stop Bit = 1, No Parity Bit, sets DTR and RTS to logical "TRUE". Now by connecting a MODEM to the RS-232 Serial port you have a pathway for data to and from the Telephone. |
| The remaining task is to connect the *CL device into LDOS. This can be achieved in several ways,but in this case we want to use the system in remote mode, so we connect *CL to the *KI (Keyboard) device for input, and to *DO (Display) device for output. In LDOS this is done by: |
LINK *CL *KI |
| This permits any request for keyboard input via *KI Keyboard to be serviced either by the keyboard of the HOST machine or via MODEM through *CL. Any character output to *DO (Display) will also be sent to *CL and thus to the MODEM, this provides the ECHO. |
| As an added bonus, the LDOS Type-ahead Keyboard Driver allow double buffering of all input via *CL. Data from the MODEM is fetched by the interrupt handler as soon as it arrives, and buffered until the next scan of th typeahead routine. The data is then buffered for use by the *KI driver when needed. |
| To complete this operation, the whole of high memory and the DCB's are saved in the CONFIG file for loading at Boot. All is now prepared so the computer can be used remotely via the phone. All the programs it will run can be written in BASIC and do whatever you want. |
| The CLUB-80 software is written in LBASIC and the programs run in "EXEC" mode(Level 7) to afford maximum protection from tampering. As an added protection a FILTER program is used on the *KI (Keyboard) device to check that the system hasn't somehow dropped into DOS READY or BASIC READY. If the FILTER finds this condition true, the system is rebooted to disconnect the current caller before they can play around. |
Frank Durda IV
To turn floppies 2 & 3 on immediately, but only for the current session:system (drive=2,enable) |
| To make this permanent, SYSGEN these settings or make these commands part of the boot jcl. |
| The MODELA/III file must be loaded from a diskette in the TRSDOS 1.x, LDOS 5 or LS-DOS 6.x format. The 4P Boot ROM doesn't understand any of the other directory/filesystem layouts, and by default the NEWDOS disk format is quite different.* |
| The normal process for booting an "alien" format diskette is: |
1. Insert the diskette with MODELA/III on it and press reset. 2. If that diskette is LS-DOS 6, press the [3] or [F3] key within three seconds. 3. Press the [P] key to indicate that you want to swap diskettes. You must also do this within the three seconds after pressing RESET. (You can press the F3, 3 and P keys in any order or all at once.) 4. The system prompts to change diskettes. Insert NEWDOS, MultiDOS or whatever non-TRSDOS/non-LDOS format OS this is. 5. Press [ENTER] to boot the other operating system when the new diskette is in place.
| Once loaded, if you press RESET or otherwise reboot, the MODELA/III image will still be there and you can boot directly onto the NEWDOS or other Model III OS without having to swap diskettes again or pressing any other keys. If you cycle power, you will have to repeat the first procedure. |
| Optional keys related to Model III-mode booting are [L], which means says to load the Model III image even if it doesn't appear to be needed, and [N], which says to NOT load the ROM-image even if it does appear to be needed. |
| * Implied in that is if you make a NEWDOS diskette with a directory cylinder pointer in the boot sector that points to a cylinder that "looks" like a LDOS/LS-DOS diskette directory track, and it contains a LDOS/LS-DOS/TRSDOS-style directory entry that points to a cylinder/sector position containing the MODELA/III file data, *then* you could load from a non-TRSDOS/LDOS/LSDOS OS, and someone has done this, but you have to make a very strange looking disk layout to make it occur and it wastes a lot of space. This exercise is left to those with lots of spare time. |
For the more adventuresome ...
| Build a diskette with a boot sector that doesn't look like a Model III-mode boot sector. This means the ROM won't try to load MODELA/III at all, assuming it's a Model 4-mode diskette. Then when the boot sector is loaded and control is transferred to it, it can do anything it wants to. You could write a boot sector that knows where to load the MODELA/III file from on this alien disk format and load it yourself before loading the rest of the OS, or you could concatenate the BOOT/SYS or SYS0/SYS modules of the operating system onto the contents of a MODELA/III file, which loaded everything as though it was one big file. Typically the MODEL%/III contents needs to be loaded first, so that later stages of the boot process will have the old Model III ROM functions available for use, such as to print those boot-up screens. |
| In theory, you could do the latter (build a blob file containing both MODELA/III and BOOT/SYS contents) and let the boot ROM do the work (ie load MODELA/III contents and BOOT/SYS that have been combined in one file), but it would be much easier to simply not let the boot ROM try to load a MODEL%/III file and take over things from there. You can't make the 4P-ROM know about any new disk formats, so the best choice is to not rely on it at all for that function. |
| To decide if the MODELA/III file is needed, the 4P ROM scans sector 1 on the floppy diskette looking for the CD XX 00 (CALL 00XXH) instruction sequences and other clues. If it finds any, it knows the boot sector is expecting the Model III ROM image to be there, so the 4P-ROM loads the ROM image first before turning control over to the boot sector. Frequently, the only reference to the "A" ROM address range in the boot sector would be to display a message like "DISK ERROR", but that one hit was enough to make the determination automatic. I recall that during development back in 1983, Frank Durda IV tested several dozen alien diskette formats, including all the Kim Watt stuff, looking for signatures like this. |
Another solution, by Tony Domigan and Northern Bytes, Vol.5, #7, Page 14
| MODELA/III can be copied to LDOS 5.x and TRSDOS 1.3B diskettes so that they can Cold Start on the Model 4P. If, however, you wish to use NEWDOS/80 version 2.0 the only option is to load MODELA/Ill with 'pause' and then enter your NEWDOS disk - two operations not very convenient. Furthermore, the Model 4P hardware seems to check the boot sector (sector 1) in a way which excludes any DOS other than TRSDOS or LDOS. |
| The method I have used relocates the NEWDOS directory to lump 36 i.e. track 20; the same track on which the LDOS directory resides, |
| The FPDE for MODELA/III is created and the directory entry modified so that when the file is copied from the TRSDOS MODELA/Ill disk it will be copied to a true track. I have used track 30 as it is not allocated in a standard NEWDOS diskette, |
| The ROM file is then modified on the NEWDOS diskette so that the bootstrap loader will select sector 0 to boot the diskette. |
| Using Superzap the MODELA/III FPDE is again modified to read Track lEH or 30 decimal and the total granules changed to 09H. The normal boot sector (sector 1) is modified with 3 bytes located by the hardware in checking for a TRSDOS or LDOS disk. |
| The diskette is now configured such that the hardware assumes it is an LDOS diskette with the ROM starting on track 30 decimal, Once loaded the ROM bootstrap boots NEWDOS from sector 0. |
| 1. | Construct a new system diskette with a directory on lump 36 - e.g. |
PDRIVE,0,1,DDSL=36,A
COPY,0,1,00/00/00,CBF,FMT,NDP=NEWDOS4P,DPDN=1
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| 2. | Boot the new system diskette, |
| 3. | Create a file called MODELA/III - e.g. |
CREATE MODELA/III:0
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| 4. | Using Superzap, page through the directory, from relative sector 360, till the FPDE for MODELA/Ill is located, Modify Bytes 21-24 in FPDE i.e. |
0000 FFFF to 3900 36DB
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| 5. | From 'NEWDOS READY" copy MODELA/Ill from the TRSDOS 1.3B boot disk to the new NEWDOS disk - e.g. |
COPY MODELA/III:1 :0 SPDN=4
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| 6. | Using Superzap locate the MODELA/III FPDE and modify bytes 20-24 i.e. |
Find 3900 360B Change to 3900 1E09
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| 7. | Using Superzap 'DFS' modify MODELA/Ill at FRS 53 Relative Byte 39 i.e. |
Find 3E01 D3F2 Change to 3E00 D3F2
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| 8. | Using Superzap modify the first sector (360) of the directory (GAT). Change relative bytes 36H to 3BH inclusive to FF (i.e. lump(s) allocated), |
| 9. | Modify Disk Relative Sector 1 at relative byte 0: Do a 'ZTFF' |
Relative Byte 02 ==> 14
Relative Byte 14 ==> 28
Relative Byte SA ==> CD
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| 10. | Now the easy part, RESET the 4P holding the 'P' and 'L' keys, If the ROM fails to load successfully then recheck the FPDE entry and the Sector 1 bytes. If the ROM loads successfully but NEWDOS fails, either partly or completely, then recheck the patch to MODELA/Ill (or perhaps you have accidentaliy written to the wrong part of the system!). |
| /sys0 | Essential |
| /sys1 | Essential - Interrogates DOS commands |
| /sys2 | Necessary - Creates files, opens FCBs, allocates file space, allocates FDEs, encodes passwords and loads user programs. Executor for RENAME and LOAD. |
| /sys3 | Necessary. Closes FCBs, kills files, inserts/deletes entries. Executor for BLINK, BREAK, CLOCK, DEBUG, JKL, LCDVR, LC, VERIFY, and PURGE. |
| /sys4 | Displays DOS ERROR messages |
| /sys5 | DEBUG |
| /sys6 | Executor for FORMAT, COPY, and APPEND. |
| /sys7 | Executor for TIME, DATE, AUTO, ATTRIB, PROT, DUMP, HIMEM, and the first part of PURGE, SYSTEM, and PDRIVE. |
| /sys8 | Executor for DIR and FREE. |
| /sys9 | Executor for BASIC2, BOOT, CHAIN, CHNON, MDCOPY, PAUSE, and STMT. |
| /sys10 | Executes BASIC statements GET and PUT. |
| /sys11 | Executes BASIC direct statement RENUM. |
| /sys12 | Executes BASIC direct command REF. |
| /sys13 | Executes BASIC ERROR messages and the first part of RENUM. |
| /sys14 | Executor for CLEAR, CREATE, ERROR, LIST, PRINT, and ROUTE. |
| /sys15 | Executor for FORMS and SETCOM. |
| /sys16 | Executor for most of PDRIVE. |
| /sys17 | Executor for WRDIRP and most of SYSTEM. |
| /sys18 | BASIC direct statement executor. |
| /sys19 | Executor for BASIC statements LOAD, RUN, MERGE, SAVE, and CMD"F". |
| /sys20 | Executor for a number of BASIC statements. Must be present if BASIC is active. |
| /sys21 | Executor for CMD"O". |
F. McCloy
| Following are instructions for initializing Radio Shack 12 & 35 Meg hard drives under TRSDOS 6.02.00 and LDOS 5.1.4 using TRS-80 models 4 &4p. These drives are not directly supported by Radio Shack for use with computers listed, and therefore, the "automatic formatting" utilities provided by RS will not give tou satisfactory results. |
| PLEASE NOTE: The 35 Meg disk has 512 actual tracks, but you can use only 404 of them due to the limitation of the TRSHD6/DCT device driver. This limits useable space to about 80% of the drive's capacity. Partitioning the drive for both TRSDOS and LDOS will not solve the problem. (All of the space on the 12 Meg drive will be available to you.) |
| Use the following procedure to initialize the 12 or 35 meg drive with TRSDOS 6.02.00. (A similar procedure can be used for LDOS using its utilities.): |
| COMMAND ---------- | QUESTIONS --------------- | ANSWER 12 MEG --------- | ANSWER 35 MEG ------ |
| SYSTEM (DRIVE=6,DRIVER="TRSHD6") | Number of heads: Tracks per surface Step Rate: # Heads/Partition Starting Head: |
1 6 230 .01 1 1 |
1 8 404 .01 1 1 |
| TRSFORM6 :6 | Disk pack name: Password: Manual Lockout: |
HARDA PASSWORD N |
HARDA PASSWORD N |
| SYSTEM (DRIVE=1,DISABLE,DRIVER="TRSHD6") | Drive Select Address: # Heads/partition: Starting head: |
1 1 2 |
1 2 2 |
| TRSFORM6 :1 | Disk pack name: Password: Manual Lockout: |
HARDB PASSWORD N |
HARDB PASSWORD N |
| SYSTEM (DRIVE=2,DRIVER="TRSHD6") | Drive Select Address: # Heads/partition: Starting head: |
1 1 3 |
1 2 4 |
| TRSFORM6 :2 | Disk pack name: Password: Manual Lockout: |
HARDC PASSWORD N |
HARDC PASSWORD N |
| SYSTEM (DRIVE=3,DRIVER="TRSHD6") | Drive Select Address: # Heads/partition: Starting head: |
1 1 4 |
1 1 6 |
| TRSFORM6 :3 | Disk pack name: Password: Manual Lockout: |
HARDD PASSWORD N |
HARDD PASSWORD N |
| SYSTEM (DRIVE=4,DRIVER="TRSHD6") | Drive Select Address: # Heads/partition: Starting head: |
1 1 5 |
1 1 7 |
| TRSFORM6 :4 | Disk pack name: Password: Manual Lockout: |
HARDE PASSWORD N |
HARDE PASSWORD N |
| SYSTEM (DRIVE=5,DRIVER="TRSHD6") | Drive Select Address: # Heads/partition: Starting head: |
1 1 6 |
1 1 8 |
| TRSFORM6 :5 | Disk pack name: Password: Manual Lockout: |
HARDF PASSWORD N |
HARDF PASSWORD N |
| SYSTEM (DRIVE=7,DRIVER="FLOPPY") | I/O ADDRESS: | 2 | 2 |
| BACKUP :0 :6 (SYS,INV) | |||
| SYSTEM (SYSTEM=6) | |||
| SYSGEN (DRIVE=6) | |||
| Your system is now set up as follows: | ||
| LOGICAL DRIVE | PHYSICAL DRIVE | PHYSICAL DRIVE |
| 12 MEG | 35 MEG | |
| ------------- | -------------- | -------------- |
| :0 | HD Head #1 | HD Head #1 |
| :1 | HD Head #2 | HD Head #2-3 |
| :2 | HD Head #3 | HD Head #4-5 |
| :3 | HD Head #4 | HD Head #6 |
| :4 | HD Head #5 | HD Head #7 |
| :5 | HD Head #6 | HD Head #8 |
| :6 | Floppy Drive #0 | Floppy Drive #0 |
| :7 | Floppy Drive #1 | Floppy Drive #1 |
| PLEASE NOTE: This procedure can provide guidelines for partitioning your 12 or 35 meg hard drive for use with both TRSDOS and LDOS. | ||
| Tim Mann / Frank Durda IV |