Z*Magazine: 23-Dec-87 #85From: Atari SIG (xx004@cleveland.Freenet.Edu)
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From: xx004@cleveland.Freenet.Edu (Atari SIG) Subject: Z*Magazine: 23-Dec-87 #85 Date: Wed Jul 21 09:09:44 1993 ______________________________________ ZMAGAZINE 85 December 23, 1987 ______________________________________ Special Edition Part 3 of 3 parts Best of Technical Help Columns ______________________________________ Series compiled and edited by: Ron Kovacs Published by: Ron Kovacs (c)1986, 1987 Syndicate Services/Rovac Assistant Publishers: Ken Kirchner Susan Perry ______________________________________ Xx A Few Notes... ______________________________________ Here is the 1988 Schedule for Zmag! NEW PUBLISHING DAY ANNOUNCED We will release new issues of Zmag every Monday. Issue 87 1/ 4/88 Issue 88 1/11/88 Issue 89 1/18/88 Issue 90 1/25/88 -------------------------------------- Issue 91 2/ 1/88 Issue 92 2/ 8/88 Issue 93 2/15/88 Issue 94 2/22/88 Issue 95 2/29/88 -------------------------------------- Issue 96 3/ 7/88 Issue 97 3/14/88 Issue 98 3/21/88 Issue 98 3/28/88 -------------------------------------- We will update this schedule if needed after this run of issues. Issue 87 will be Volume 3 Number 1. ______________________________________ Xx INDEX 85 ______________________________________ <*> A Few Notes.............Ron Kovacs <*> 256/320K Ramdisk....Steve Ingalsbe <*> Modify 850 Express......Ol Hackers <*> SG10 Printer Driver <*> SX212 Review...........Bob Woolley <*> 850 Modification........Mike Davis <*> Speaker Addition.....Mr. Goodprobe <*> 1050 Notes.................Ed Chop <*> Notes on XModem...........TeleTalk <*> DataPac Parameters......Ken Watson ______________________________________ 256/320K Ramdisk ______________________________________ 256XL/320XE Ramdisk Installer Version 1.0 Distributed by the Twin Cities ATARI Interest Group (TAIG), Mpls. Minnesota Original program by Claus Buchholz - 320XE modifications by Steven Ingalsbe The need for this program arose after I had modified my 130XE into a 320XE. The only DOS I had that would work with all of the extra memory was SpartaDos. This is a nice Dos, but does not allow me to use the warp speed of my INDUS. I also use a modified Dos 2.0 a lot, and had no way of using it with the 17 banks of memory that I now had. I tried loading one of Claus'QXL files into my system, but it just locked up. I got a copy of the source code and looked it over. The only problem I could see was the way he was switching the OS off, so I changed that portion of the program so it would work with all the XL/XE series (it should work with a modified 1200XL also!). The program loads the XL/XE operating system into the underlying RAM and then turns off the ROM Operating System(OS). Next it loads the Ramdisk handler over the European character set and then hooks itself into the system. This handler (like Claus' original)does not format the drives on powerup. You must do that with the I function of DOS, or use a XIO 254 from BASIC (drives 3 & 4). I also made a few other minor changes. I reassembled some of his code to different memory locations; his code was at the end of ATARI DOS. Many third party Dos's use more memory than ATARI Dos, so I moved the code up. It has been tried with ATARI Dos 2.0, and 2.5 as well as Dos 2.6 (highly modified). It also will work with MYDOS,TOPDOS, and SMARTDOS. I have not been able to get it to work correctly with DOSXL, it will only setup 1 single density RamDisk. I feel that 1 single density RamDisk with Synchromesh is better than none. There are 2 popular programs that will not work with this handler-SPARTADOS and BASIC XE. Both of these programs need the RAM under the OS for their own use, and we have that tied up. SpartaDos has its own 256XL and 320XE handlers so that is no big problem, but there is no cure for BASIC XE, sorry. There may well be more programs that will not work, but most do. There are a few other things you should know. Don't press system reset; it will cause the system to reinitialize. This causes the system to go back to the ROM OS. If you do press system reset, you can get back to the RAM OS by POKEing 54017,252. Also, make sure that you set your DOS up for the added drives. Most DOS's are shipped set up for 2 drives. I always set mine up for 4 (2 physical and 2 RAM drives). All of the DOS's that I have seen use location 1802 as the number of drives location. All that you have to do is POKE 1802,X then goto DOS and write the new DOS files. The change will now be permanent. Use this guide to find the right number: # of drives POKE 1802 with ================================= 1 1 2 3 3 7 4 15 NOTE:The drives are set up as 3 & 4, so you should POKE 1802,15 unless you have more than 4 drives. ______________________________________ Xx Modifying BBS Express (850) ______________________________________ From:The Ol' Hackers BBS(516)-884-4140 If you have an AVATEX 1200 or the AVATEX 1200hc this modification may help your log-ons. I made these mods because I didn't like the fact that the users had to hit Control-M or S to log-on the 850 version of BBS EXPRESS, so I modified a few bytes to allow the users to log on by just hitting the Return. The mods are split-up into to Two Parts, Part(A) is for the non-HC version of the AVATEX, and Part(B) is the change for the AVATEX 1200HC. The two area's which you are going to change affect the baud step rates and the defaults of the the EXPRESS BBS program for your modem to pick the phone by starting the baud rate at 300 baud. When BBS EXPRESS 850 hangs up the modem, it initializes the modem to default configurations, and sets the port and modem back to 300 baud. We are going to modify part of the code in EXPRESS BBS. So don't use your original disk, and get your favorite disk sector scanner. I suggest that you use DISKWIZ II, if you have it. First format a disk in ATARI DOS 2.0 S/D and don't write any DOS files to the disk. Now copy BBS.COM to your formatted disk. PART "A" AVATEX 1200 Non HC Starting at sector 68; With byte $38 $00 $0A $0C -- change this to $0A $00 $0A. $00=300 Baud $0A=1200 Baud $0C=2400 Baud Since you have the AVATEX 1200, byte # $32 should be changed to $0A for 1200. Now write sector 68 back to the disk. Starting at sector 271 With byte $39 Your changing the text, which tells the printer log and the user at what Baud rate he or she logged on with. $33 $30 $30 $04 $31 $32 $30 $30 $04 $32 $34 $30 $30 $33 $30 $30=text 300 $31 $32 $30 $30= text 1200 $32 $34 $30 $30=text 2400 I made the following changes; $33 $30 $30 to $48 $2F $53=H/S for 1200 Baud. $31 $32 $30 $30 to $53 $6C $6F $77= Slow for 300 users.(hint to get them to change over to 1200. $32 $34 $30 $30 to $20 $48 $2F $53= Blank Space then H/S, 1200 again. Now write that sector back to your disk. That's it for the non-HC AVATEX 1200. PART "B" AVATEX 1200 HC Mods Use the changes in "Part A" with the following additional change. Starting at sector # 274 At byte $58 $A0 $00 $8C $7B $30 Change the $00 at byte $59 to $01 $00=300 Baud $01=1200 Baud $02=2400 Baud Now write this sector back to your disk and BOOT up. Things that will change with your log-ons. 1) Non HC AVATEX: after the first line of garbage the 1200 user only hits the Return key once and he gets the HIT RETURN prompt. No more hitting the Control-M or S keys or having the user log-on first in ASCII then changing over to ATASCII. 2) The AVATEX HC, will at the connect automatically prompt the 1200 users to HIT RETURN without any key strikes at all. Note: I'm sure that the "HC" changes will work with any modem that is a Hayes compat or the the real Hayes 1200. Also PARTS "A and B" will work with both versions of the AVATEX, however, the non HC version will show the user the ATA command then prompt them to HIT RETURN. Special thanks to Keith Ledbetter for writing the NEVER crashing BBS EXPRESS and to Chris King for the Hard Drive back-up program (HARDBACK). Both authors are with ORION Micro Systems. _____________________________________ Xx SG10 Printer Driver _____________________________________ After 2 years of frustration and many dollars spent on "custom" printer drivers, I think I have a solution. Below is a printer driver that I have been using with great success to solve many of the Star Gemini - AtariWriter+ problems. It may give you some ideas to help you build one that will suit your own needs. UNDERLINE DRIFT Most of my word processor print outs require underlining in NLQ. If you have tried this with inverse video underline command you will have a problem with what is called underline "drift". The words and underline "drift" down as the printer does half spacing. Since I seldom have need for superscript or subscript, I have eliminated the type font macros for these and substituted direct codes for underline on and underline off (AW+ [controls G8 and G9 are what I use]. My printer driver allows for the use of inverse video when in draft mode. To underline in NLQ I use the G8 to begin underline and G9 to end underline. NO DRIFT!! Many times I will creat my document using inverse for rough drafts and then when I am ready for final print out go back and visually key off the inverse video, insert the G8 and G9 codes there and "undo" the inverse video using [control] U. You will also find that the G8 and G9 codes will give you a "solid" underline (underlining the spaces between words as well). TURNING OFF NLQ AND MIXING FONTS My printer driver allows some degree of flexibility to change fonts using the "G" codes. You will note that all Font type commands begin with 27 66 5. This is the SG10 code to turn off NLQ. If you are in NLQ and want to change to italics with double strike you may do so with G5 and G7 command. If you look at the G1 (pica) commands you will see the commands to turn off all the other font styles. It is important to remember that you MUST "pass through" G1 to move from all typestyles except NLQ or you might get some funny looking print outs. In effect G1 will "undo" everything (except underline) and put you back in draft mode. If you have need for subscript and superscript AND NLQ underlining, you may need to make modifications to this program. This can be done by substituting sub and superscript for perhaps Elite and condenced fonts. If you do this be sure to also substitute the "turn off commands" in the G1 (pica) codes. It would be a good Idea to keep a print out of which G codes you are using for what on hand. It may also be necessary to build more than one driver if your documents vary in format. Hope this is of some help to all the SG10 users. CODES TO ENTER FOR EDITOR PROMPTS: Underline off blank Underline on blank Backspace 8 Elongate off 27,87,0 Elongate on 27,87,1 Bold off 27,70 Bold on 27,69 Up 1/2 line blank Down 1/2 line blank Down 1/2 line and CR blank Return w/o line feed 155 Font Type Codes ========================= 1 Pica 27 66 5 27 53 27 72 27 112 0 2 Condensed 27 66 5 27 66 3 3 Proportiional 27 66 5 27 112 1 4 NLQ 27 66 4 5 Italics 27 66 5 27 52 6 Elite 27 66 5 27 66 2 7 Double Strike 27 66 5 27 71 8 Underline on 27 45 1 9 Underline off 27 45 0 ______________________________________ Xx SX212 HARDWARE REVIEW ______________________________________ by Bob Woolley For those of you with no modem, or a SIO connect 8-bit modem, or a 300 baud modem (leave anybody out?), Atari has got a great new product for you - the SX212 1200 baud modem. It has a standard RS-232 interface for those users with an 850, or an ST, or a P:R Connection and an SIO connector for those 8-bitters who lack an RS-232 box. It is Hayes compatible and even has a nice row of LEDs accross the front of the unit to keep you informed of its status (High Speed, AutoAnswer, Carrier Detect, Off Hook, Receive Data, Send Data, Terminal Ready, and Modem Ready). The best thing about this guy is that it only costs $99.95 - List Price. A product of increasing integration, it is another level up on the path to single chip, 1200 baud, modems - much like the 300 baud XM301 that preceded it. I can remember my first RS-232 modem. It was also Hayes compatible, which seems to mean that it has to have 6 million switches set before your computer will talk to it. Not the SX212. Absolutely nothing to set on this guy. Move it from your 8-bit to your 16-bit system ... works just fine with no switch juggling. Aren't any to mess with, anyway. My X-Ray Vision tells me that there are jumpers inside, but it isn't something the average guy is going to fool with. I tried the 212 on my ST with FLASH. Although I am not any kind of TP expert, the modem worked just fine. It seemed to be perfectly happy with XModem downloads and such. Even the operator trying to interrupt my call didn't bring down the modem. Lots of garbage, but carrier stayed up. This is exactly what the computer industry needs - an affordable product that you just pull from the box and run! When it came to my 8-bit system, I hit a little snag. Since the modem would connect to the SIO port, it has to either emulate an 850 and the Hayes modem, or not emulate the 850 and not work on my 8-bit. Guess which one I got?? Works just fine on the P:R Connection as a Hayes (knew that since it worked on the ST) . Didn't work at all as an 850. I tried a Status command to every address on the SIO buss and got no response from the SX. One thing for sure, no matter how it works, the modem requires a handler. Some devices load their own handler and some programs replace them with the handler that the program wants. So, without a handler, I had no chance to make the thing work. If the device didn't even talk to the CPU on the SIO buss, how could the handler talk to the modem? The XM301 modem came with an excellent communications program and plenty of documentation on disk to fully describe the handler necessary for that device. I quickly learned that an SIO cable (which is not included in the box - for obvious reasons. You can't use the SIO feature without the handler) and a version of EXPRESS will become available from Atari at some future date. I should hope so. Not requiring a P:RConnection or an 850 can save an 8-bit user as much as the cost of the modem itself. This is one of the greatest assets of this device, the ability to run without additional interfaces. Needless to say, this was most discouraging. Maybe a little hacking could help? There was (is?) a company called Advanced Interface Devices that made a simple RS-232 adapter for the Atari SIO buss. Since the SIO is already a serial buss that can be programmed to operate in almost any mode, they thought they could just write a handler and wire up a cable that would suffice for RS-232 operation. They produced the R-Verter and managed to do exactly what I described - run the SIO as an RS-232 serial interface. With this in mind, and a little more X-Ray Vision, it appeared that Atari was using the same method on the SX212. There is a two chip modem set, a couple of RS-232 receiver/driver chips, an audio amp, an LS logic chip, and some sort of clock generator inside this modem. It would be very unusual for a modem chip set to be able to talk to an Atari SIO buss directly (the XM301 uses a microprocessor to operate as a modem and to talk to the buss). So, I had to conclude that Atari used the R-Verter approach. Close inspection of the SIO pins indicate that the -Command line (pin 7) is not even connected in the SX212. No way to do SIO without that pin. No SIO means an RS-232 emulator. The only one that I am aware of is the AID R-Verter. So, I logged on to CompuServe and looked for an R-Verter handler in DL2. Luckily, I found exactly what I needed in a file called RVHAND.XMO. It is an R-Verter handler that has been re- compiled for use with HOMETERM. Following the RVHAND.DOC file, I created a copy of HOMETERM that would run on the R-Verter. Booted up on my SX212 and got the 850 status screen. Even though the modem is directly connected, the program thinks it is talking thru an 850. All the commands that I needed worked just fine on HOMETERM-downloads, disk directories, pauses, everything! Tom Neitzel has passed on the word that the same handler will allow the SX212 to run Amodem 7.4, a program that I am not familiar with, but is very popular. I have not tried to replace the handler in EXPRESS with the R-Verter code. I don't think that task will be as simple as re-compiling the code, since EXPRESS seems to use all available memory. None the less, those 8-bit users who own SIO connect 300 baud modems can upgrade to the SX212 and start tele-computing immediately with Amodem or HOMETERM. One or two more comments. The manual states that the modem cannot be used on an 800XL with a cassette recorder. The Motor line is fed into the modem and is grounded thru a 680 ohm resistor. This appears to upset the 800XL or the recorder or somebody. I don't see any significant differences between the 800XL and the rest of the Atari line in this respect, so expect this restriction to apply to all 8-bit models. A suggestion is made to place the modem on top of your disk drive and the phone on top of the modem. Some telephones have magnets in them - put it someplace else if you are not sure. Some disk drives generate considerable heat, while the SX212 seems very cool. I put my modem under my drive, leaving the vents on top of the drive clear for good cooling. The bottom line on this modem is that it is a great value for the money, performs well and can be used on either 8 or 16 bit systems with a minimum of expertise. The 8-bit software is not yet available from Atari, but even that can be fixed for the time being. No modem offers you so much for so little. Don't overlook this bargain!! ______________________________________ Xx 850 INTERFACE MODIFICATIONS ______________________________________ by Michael T. Davis Since I run a BBS here in Ohio, I have the "need for speed" that most SysOps who run Atari (8-bit) based BBS' usually have. One of the things I discovered early in my BBS setup, though, was that the software I was (and am) using (Carina) did not handle premature logoffs well. Instead of detecting the loss of carrier immediately, it just timed out. I was almost positive there had to be a better way. The second problem I was encountering had to do with the fact that the 850 doesn't reset per se. To reset the interface, you have to toggle the power switch off and on. This can get annoying if you are constantly switching telecommunications software or if your 850 is in a hard-to-reach place. Solution One: First of all, it would simplify matters greatly if you have a 130XE. While the modifications I am going to describe should work with all (8-bit), Ataris I can only give specific directions for the 130XE, as that is what I use. At points throughout the text, I will offer possible alternatives, when I am utilizing an XE-only feature. The 130XE does not use trigger input four from the missing joystick four port. We can use this input on the GTIA chip (pin ten (10)) to monitor the Carrier Detect line in the 850 almost constantly. (By the way, this would be a good time to put in a plug for Sam's Technical Reference Sheets.. they're great for just this kind of work.) Anyway, first identify the Carrier Detect (CRX) line on port one of the 850. Looking at the port, CRX is the fourth pin from the left on the top row. Now follow this line into the 850. You are trying to find capacitor number 117 (C117). It will be the next-to-last capacitor in a row of capacitors. We will attach a jumper wire to the side of C117 that runs to the 6532 RIOT (RAM, Input/Output, Timer) chip. Solder it in at that point any way you like. The other end is a bit tricky for non- XE owners. Actually, the XL series could probably follow the XE scheme, but the locations of the circuitry will be different. For XE/XL owners, solder the other end to pin 12 of the SIO port (either one). Pin 12 is the top right pin, as you look at the port. If you're doing this for a 400/ 800 setup, you might try pins 9 or 13. Note that using either of these, however, will prevent use for their original purposes (Proceed and Interrupt lines, respectively). This isn't too big of a deal, since no one has taken advantage of these lines to date. As for the computer side, simply solder a wire directly from pin 10 of the GTIA chip to pin 12 of the SIO port. Users of computer models other than the 130XE should connect this line from the GTIA to the appropriate SIO line..the same line they connected the jumper wire to in the 850. Now determining the status of CRX is simply a matter of a PEEK to location 53265 ($D011). It will be either on (1) or off (0). CRX provides an inverted output; that is, if you get a 1, then there's NO carrier, a 0 means there is a carrier. Solution Two: Find pin 1 of the 6507 in the 850. This is the Reset line (and it is active low). To reset the interface, we will run a line from this pin, through the SIO cable, to pin 39 of the PIA. Note that this will prevent the use of a cassette recorder (but then who does serious work on cassette nowadays, anyway). Connect a wire from pin 1 of the 850's 6507 to pin 8 of the SIO port. Now, the tricky part: in the computer, cut the trace to pin 39 of the 6520 PIA. MAKE SURE YOU ONLY CUT THAT ONE TRACE!!! Also, to make sure we are geting a clear signal, it would be a good idea to cut the trace at pin 8 of the SIO port in the computer, too. Then connect a wire from pin 39 of the PIA to pin 8 of the SIO port within the computer. To reset the 850 now, we need to lower bit 3 of PACTL (54018; $D302). In BASIC, this is accomplished with POKE 54018,52:POKE 54018,60. (60 resets PACTL to its original value and puts the 850 back in "normal" mode.) Note that if you wish to write an assembly language routine to accomplish this, you should use a suitable delay between the time that you lower the bit and the time you raise it back to logic one. Conclusion: If you have any problems, or you just want to get in touch with me, I may be reached on CompuServe's Atari 8-bit SIG (ATARI8). My User ID is 72337,2075 I am also online in Columbus, Ohio on most of the major Atari BBSes, including Pandora (614-471-9209) and ACEC (Atari Computer Enthusiasts of Columbus; 614-471-8559). ______________________________________ Xx SPEAKER ADDITION ______________________________________ Those Were The Good Old Days by Mr. Goodprobe Ah, remember when you could go down the boardwalk and smell the nuts roasting in the little shops, bikini's were the most eye-catching thing around beside mini-skirts, and skateboards had metal wheels? Some of the things from then I dearly miss, and others not at all! Those killer metal wheels on skateboards quickly disposed of several pairs of jeans in my teenage years, and accounted for numerous shredded elbows, knees and jackets! The Atari 800 had one of the finest keyboards available on the home computer market, and the entire unit was designed with longevity in mind. One nice touch the 800 possesed which was eliminated with the advent of the XL series was the internal speaker. I can remember a game I used to enjoy on the 800 whose name escapes me at the moment. The general idea was to spray the garden with bug spray to rid your plot of pesky bugs that would flutter about and devour your veggies. As the bugs appeared on the screen, from the internal speaker would arise such a clatter that you would really have to stop as it sounded for all the world that they were ACTUALLY inside your beloved computer...it was an uneasy feeling to be sure! Now, just because you upgraded to an XL/XE doesn't mean you have to do without this feature any longer! This will be one of the simpler projects you will undertake, but its rewards for the installer will far exceed the effort expended. This article will cover the version I whipped together for the 800xl, and next issue we will share the version for the 130xe with you. Parts you will need: 1. Diode: Part # ECG 177 2. Transistor: Part # ECG 123AP 3. Capacitor: .001 @ 50v 4. Resistors: 1k 1/2 watt 100 ohm 1/2 watt 5. Speaker: 8 ohm 1/2 or 1 watt variety (The smaller the physical size the better) 6. Small hook-up wire Construction: Dissemble your 800XL, remove keyboard, metal shield, and screws and place these items safely aside. You will not need to remove the PC board from the bottom of the case. 1. Attach wire to bottom side of C23. This capacitor can be easily located by first looking directly between the RF modulator and the cartridge slot on the right. find the middle ground between these 2 points, then mentally draw a line 3 inches long back toward yourself from this point and you see C23. Just above and to the right of this part is a small electrolytic standing on end. Found it? Good! 2. At the other end of the wire attach your 1k 1/2 watt resistor. 3. The neatest way to build this project is to build a large portion of the needed circuitry right onto the speaker itself. Using the lead placement chart solder the collector of your ECG 123AP transistor to one of the lugs on the speaker. | | \ * * * / \ E B C / \ / \------------------/ (Bottom view with pins facing toward you) 4. Grasp your ECG 177 diode, and connect the end which DOES NOT have the band on it to the same lug on the speaker as you connected the collector of the transistor to. 5. Connect the front (banded) end of the diode to the other lug of the speaker. 6. Connect the 100 ohm resistor to lug of the speaker with the banded end of the diode. 7. Connect the .001 capacitor to the base of the transistor. 8. Connect the free end of the 1k resistor to the base of the transistor. 9. Locate the small 8 pin IC. notice the small dot on the bottom left corner. This is pin 1. Count over to pin 4, this is the point we will use for ground. Connect a wire here. 10. Connect the other end of this wire to the following parts: A: The free end of the .001 capacitor B: The emitter lead of the transistor 11. Locate C14. This capacitor is located directly to the left of the modulator. The top of this cap is our 5v source. Solder a lead to this point. 12. Connect the free end of this lead to the free end of your 100 ohm resistor. All that remains to be done is locate a spot to mount the speaker inside of the cabinet of your XL. The smaller the physical size of the speaker you have chosen, the easier your task for finding the needed space will be. Also, it might be wise to use electrical tape to insulate all exposed wire leads of your add-on to avoid any future problems. Keep those Atari's hummin'! Mr. Goodprobe (on lend from) Midtown TV Atari 8/16 Sales/Repair (216) 633-0997 _____________________________________ Xx 1050 Notes _____________________________________ By:Ed Chop Did you know that Atari made two 1050 drives? The newer drives are Tandon drives and the older drives are WST (World Storage Technologies). It seems that the WST drives are quieter and more reliable, but the belts are more expensive. The WST drives are generally not marked as to manufacturer, but they have NOVACON motors. What about these cheap SD drives you see advertised in Computer Shopper all the time? Can you use them on your Atari? Well....yes ....and no. You can't use them without modifying the drive or your computer. By adding a microprocessor and interface circuits to the drive you could probably get it to work with your Atari just like a 1050. But an easier way may be to take the mechanical drive assembly from the cheap drive and wire it to the 1050 electronics. And why go through all this trouble? Because the cheap drive that you want to buy should be gear- driven. They are MUCH quieter and reliable. According to Bob Wooley,from the Compuserve Atari Sig Community, the drive must be one that draws less power than the original. Bob says that you may burn up your driver transistors, although he hasn't tried it himself, yet. Another way would be to add a PIO to your computer. That's a parallel I/O adapter. Mmmmmmmm..sounds interesting, huh? Well it seems our friend Bob Wooley is working on such a project. The PIO board will plug into the PIO port in the XL with a 24" cable. The information for building the PIO will be available on the Atari Sig when he has it completed. By adding the proper controller chip to the PIO, you can run the new drive with your Atari. But Bob has a better idea. How about a parallel 1050 drive that can load a disk in 10 seconds? Got your attention, huh? Well, he has an interface card planned that will plug into the PIO to run your 1050. That, too, will be available on the Atari Sig. We'll be looking forward to that hardware project. What's Atari doing to enhance their drives? Well, to start with, Bill Wilkinson is working on a new DOS called A-DOS. Although originally planned for the promised 3.5 inch disk, now scrapped, A-DOS is being designed for a new DD 5.25" drive from Atari. _____________________________________ Xx NOTES ON XMODEM _____________________________________ Ctsy TeleTalk Magazine Issue 12 QUESTION: "I use XMODEM across the system and transfers take twice [or thrice] as long as they should. Why?" ANSWER: As best as I can tell, the information we were passed from the Net Exchange BBS was well-meaning but wrong. Here is the scenario as I figger it--someone let me know if I'm wrong, too. XMODEM sends data in a 132-byte block that resembles a mini-packet: <----------Direction of transmission [SOH] [#] [#] [DATA] [CHK] | | | | |___ChkSum | | | +128 bytes of data | | |_________ block number | |_____________ Block number |_____Start of header (ASCII 01) This closely matches the size of a Telenet packet (generally 128 bytes) and can, for our purposes, be considered a packet's worth of data. PC Pursuit is set to forward data only on full packets and on expiration of idle timers (which are set for 1/10 second). The delay occurs because a connection through PC Pursuit goes through four modems and two entirely separate data transmissions. Each block of data must undergo the following (assuming a download from the BBS to the user): _____ _________ __________ | |__ ( )__ | | | BBS | /__( PDN ) /___|PCP user| |_____| (_________) |________| |_____| |_______| |_______| | | |_____ 1.1 | |_Variable (0.1/1+ |__________1.1 seconds That's potentially 3+ seconds to transfer data that would take slightly over 1 second to transmit in a direct connection--maybe 35% efficiency. To make matters worse, the acknowledgment (ACK) from the user to the BBS may take upwards of a second- -instead of a fraction of a second-to be transmitted back into the network, have idle timers expire, be forwarded to the outdialer, and be transmitted to the BBS. As you can see, though, the real delay is *not* because of the delay in sending the ACK, but because the block size and packet size so nearly match, the two computers are almost never working simultaneously. A protocol that uses a larger block size--YMODEM, for instance--will run faster over the system, but not because it needs fewer acknowledgements. Instead, while sending the larger block, it causes data forwarding on a full-packet condition. After the first packet gets sent, both machines are doing work for most of the rest of the transmission, as such: BBS USER """ """" Start of 1K block Sends packet 1 Does nothing Sends packet 2 Receives packet 1 Sends packet 3 Receives packet 2 Sends packet 4 Receives packet 3 Sends packet 5 Receives packet 4 Sends packet 6 Receives packet 5 Sends packet 7 Receives packet 6 End of 1K block Sends packet 8 Receives packet 7 Does nothing Receives packet 8 (Of course, the BBS is not really sending the *packet*, just a packet's worth of data.) In effect, YMODEM wastes only 2 of every 9 128-byte transfers; it should run at about 75% efficiency. In addition, since it only has a single ACK per kilobyte (instead of 8), less time is spent in waiting for the idle timer to expire. Of course, to make things more confusing, there are XMODEM packages using 256-byte and 1K blocks and XMODEM packages that allow a "window" of unacknowledged blocks to be sent, among other flavors. Recently, the default parameters for the PC Pursuit ports were changed; by whom, I don't know. For best results, users should break to command mode and set X.3 parameters 1 and 10 to 0 (disables break to command mode and word wrap) and set ITI parameter 57 to 1 and parameter 63 to 0 (enable 8-bit transparent mode). This is all done with similar commands as those issued when connecting to Exec PC. _____________________________________ Xx DATAPAC PARAMETERS _____________________________________ Ctsy CompuServe Atari8 Sig #: 188501 S2/Telecommunications 26-May-87 02:14:07 Fm: Ken Watson 73157,3100 To: John Oetter 73657,771 (X) Hi John, The method you describe will work if you are going through a Datapac public dialport but not if accessing Datapac through iNet 2000. iNet will _NOT_ allow the user to have a transparent profile (which is what PROF 3 is suppose to give you) so you cannot do any Xmodem U/L to CIS if you are using Datapac through iNet. For downloads I use a slightly different PAD paramater which is as follows: PROF 1 SET 6:0,126:4 like PROF 3 you won't be able to see your last bit of typing. Unlike PROF 3 (correct me here if I am wrong about PROF 3), you will get your character echo back after you do the D/L and your profile will remain open for subsequent downloads while you remain on CIS. Anyway, until iNet installs new software that will allow 8 bit transfers you cannot U/L to CIS if you are using DATAPAC through iNet so poor schmucks like myself continue to be able to D/L from CIS but not do any 8 bit U/L. Ken Background Datapac essentialy invloves itself as a middleman. When you type a letter, Datapac decides who it is going to, sends it, and in this case, is echoed back by Compuserve. This involves time delays that make it next to impossible to download! The packet switching used by Datapac can be overcome. Solution The trick is to get Datapac to switch off the packet switching. So here's what you do: Type a CTRL-P <^P> This is a Datapac access code. Then type PAR followed by a <CR>. Type PROF 3 <CR> (you will not be able to see what you are typing) Type SET 2:1 <CR> <CR> Now type in the Compuserve forum commands to download. Once again the sequence should go: 1. CTRL-P 2. PAR <CR> 3. PROF 3 <CR> 4. SET 2:1 (remember, you won't see this line) <CR> 5. <CR> Happy downloading and uploading! If you have any comments or suggestions, please let me know!! John Oetter 73657,771 ______________________________________ ZMAGAZINE 85 Special Edition 12/23/87 Next Issue: 12/30/87 BBS Systems Issue. (c)1987 Ron Kovacs Volume 2 Number 52 ______________________________________
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