tf_hh
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Posts posted by tf_hh
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A lot of things already said here.
IMHO it makes a huge difference in the way the seller offer his items. Some people offer dirty, dusty and nasty looking goods for superlunary prices, I call them fools. But some other tested the goods, clean it, make good arrangements and - absolute important - offer COMPLETE systems. The main unit, all needed cables, power supplies, maybe a bunch of software titles and joystick(s). Such proposals will end in high prices sometimes. What´s wrong with that? I didn´t see any reason to be angry about that. A good seller has used hours and maybe days to clean up, repair, test, complete, ... the items and make a fine compilation.
The other big point is.. don´t forget the emotional facts. As already some wrote here, most buyers (as users here, too) are aged 40 years or above. It´s a "get the youth back" thing. The "good old times", whatever you call it. The same reason why people in these ages buy a 25 or 30 year old car with simple (or no) electronics, easy to repair and fixable at home without expensive and hard-to-get tools or extremly technical knowledge.
Maybe also a lot of people are "back to retro" for the same reasons like myself: Slow-motion of time. Deceleration of all. The ability to understand exactly what´s happening in the machine, in the chip. Understanding programming, coding with success - without the need of installation tons of tools, reading 10 books and trying out for months. Everybody can learn Basic in a week or 6502 in a few. I´m a technician, a nerd, having often the newest gadgets, working with enterprise stuff equipped with petabytes of storage, hundreds of machines, power as much you want. But I´m only a user anymore - I didn´t really understand what´s going on there, I use it. I can administrate some things, some not. Most times it´s just a "black box".
The wish to use something understandable, something slowed down, not always at the current social highspeed, something emotional with good reminders of the own youth... that´s the result why some people pay 200 bucks and more for an Atari 800XL.
IMHO!
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hmmm, maybe good to note which mech is in use and stepper etc an rom configuration...
I have only Tandon drive mechanics in use. But I´m pretty sure, the result is not dependent on the mechanics nor the firmware. You can do adjusting also with 6507 CPU, 6810 RAM, 6532 RIOT and ROM/EPROM removed without issues.
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Very interesting these different results
But, overall I can´t see any problem even if you use 230 nS or 250 nS. I setup two fine working drives using my instructions in the first post, one with 230 nS setting, the other with 250 nS. Both drives are running for more than 30 minutes before. Both drives are stock drives, good adjusted RPM speed and the same firmware ("L").
I take 5 different disks, format them using single density and medium density, write data (all sectors full) and put these disks to the other drive, read them out. If all is fine, I try to write to this disk without formatting it. Works fine. Read back the whole disk in the 1st drive. Works fine. This test I repeat with both drives for all 5 disks.
Last test: I put two Minispeedy 1050 into the drives and repeat the test with double density. Also no problem at all - in both directions.
When I have had drives for repair with problems using medium density or double density AND something of the adjustments were wrong, then the differences were much higher than discussed here. For example, with one WD2793 I measure below 180 nS and this setting prevents the drive from successful formatting and writing above track 25 approx. Also if people totally screw up all pots, sometimes the drive can´t ready ANY other disk than their own formatted one. And so on.
So after all, if somebody has problems with a 1050 drive, it´s a good thing to check the settings. What you use at the end - 230 or 250 nS - may be something like a personal flavour
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Hi,
the SRAM charger boards are ready. Take a look at the final version:
As you can see in the picture, two versions exists. The left one for the genuine Indus GT drive with right-angled connector and the other version with straight connector for the clone drives LDW Super 2000 and CA-2001.
Users of the genuine Indus GT drive just need to open the case, plug the SRAM Charger board in and that´s all. Users of the LDW Super 2000 or CA-2001 must do some solder jobs to make the SRAM Charger board usable. In the manual I will link to Trub´s site with some additional infos.
If you want to place an order, please look about the handling into my catalogue PDF file with all infos.
Click here to read the info PDF
Jurgen
P.S.: The manual isn´t ready today, I will complete it in the next days, so that the manual will be finished before the first parcels received their destination
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Hi,
I didn´t found the exact way explained in any of these datasheets. I collect my experiences from what I read at other sources and primarily what I measure at untouched 1050 drives.
I grab into my boxes in the basement today and found another two 1050 PCBs. They were loose, without mechanics, but IMHO untouched. The shielding cage was intact, the pots and caps have their wax without any traces of a tool like a scredriver. Look at the pictures below my text.
The first PCB got after 10 minutes warm-up time:
Pin 16 ==> 3.840 uS (should be 4.000)
Pin 29 ==> 0.960 uS (should be 1.000)
Pin 31 ==> 228 ns
The second PCB got after 10 minutes warm-up time:
Pin 16 ==> 3.900 uS (should be 4.000)
Pin 29 ==> 0.950 uS (should be 1.000)
Pin 31 ==> 230 ns
When you measure in less than 5 minutes warm up time, the values are mostly below 224 ns at Pin 31.
So I got at four untouched and sealed (pots and variable cap or whole drive) something around 230 nS. So I can assume that this is the setting Atari did use. The reason may be discussed further...
Jurgen
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The paragraph highlighted is not for calibrating write pre compensation, but for the data separation rate. It is still possible that 250ns might be the correct calibration value as a consequence of the circuit doubling the nominal 125ns period at some point. The datasheet is not clear about that.I'm not sure about the 230ns vs 250ns difference because of the 288 RPM (vs 300 RPM) makes much sense. Most controllers perform 125ns write precompensation regardless of the drive RPM. You say that you read 230ns on most drives, but Hias read 250ns on his one.
Yes, you´re absolutely right - I miss that point. But when pin 29 is RPW - for reading - than a little lower value than 250ns according to the lower rotation speed is the consequence IMHO.
This information and the need for adjustment I got some years ago from the ABBUC floppydoc Erhard. Because I was interested in the whole thing, I dig - or try to - more into the datasheets and so on. In my collection of 1050 drives I found three models with untouched main PCBs into drives with untouched seals, also the named pots and variable caps in the first post have intact sealing wax drops.
These three drives I let warm up and check the current setting. All three were around 230 ns, a little bit less, a little bit more. Maybe it´s a random experience, of course.
I will try some tests with 250 ns setting the next days.
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Where did you find that? In the 279x datasheets I can only find the adjustment procedure and that write precompensation is adjustable between 100 and 300ns - but no recommended setting. Could well be that I'm blind and missing the relevant part though :-)
Real exactly "written with blood" I also didn´t found anything to this point, but @ WD datasheet on page 10:
My interpretation is here: "250 ns for precompensation is default".
Another independend DIY project I´ve looked for more infos is found here: FDC ZFDC Floppy Board for S100 computers - Scroll down to "Adjusting the Data Separator setting of the WD2793".
Other projects are found with the WD279x and they repeat the datasheets or name it seperately, like here: Floppy Disk for PDP-11
So I think, 250ns is correct. Why Atari used 230ns... unknown. But I think, 250ns would also work fine.
Jurgen
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i dont fully understand the "VA" measurement of the Atari device AC output but many aftermarket AC power supplies dont use that format, they just list an "a" number instead.
i thought the info from the thread may be of use in case people on here were found aftermarket PSUs that just list the "a" number - so they can make an informed decision.
anyone know how to explain "31VA"?... is it old terminology?
No, in the days were power supplies have an efficiency factor below 75% and less, it was common to declare the max. power in VA (Volt-Amps). The simple reason: This value is higher than the real power in Watt. So it´s a typical marketing / advertisement thing... today it´s more common to use Watt instead of VA.
Take a look here. This whitepaper explains in english the differences between Watt and Volt-Amps (VA).
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Hi,
In case anyone needs to know, I found a cheap drop-in replacement for the PIA:
https://www.ebay.co.uk/itm/2pcs-MC6821P-MC6821-Peripheral-Interface-Adapters-DIP-40/281278693561
I needed one and it arrived today - plugged it in and the Atari is now working fine!
You should do some extensive tests... the 6821 is only specified for 1 MHz clock. The 2 MHz version as needed for the Atari 8-Bit series is 68B21. Of course a lot of chips would work flawless with "overclocking", but... it might be show any sideeffects at any time.
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I saw that document just the other day and wondered what it was: 1050 Klon. I couldn’t find much of anything other than that doc.
IMHO there´s not more availible - that´s only a proof-of-concept, but was never build (by Bernhard Engl). Looking to some of these "TOMs drives" schematics and other solutions made in Poland looks similar to that idea.
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One question: where did you get the nominal values for read pulse width and write compensation pulse width from? I've glanced through the 1050 docs I had here (techref and Sam's) and the WD297x datasheet but couldn't find any info on these.
Several sources - See these Datasheets:
Texas Instruments FDC - beginning at the bottom of page 10 and following pages the setup is explained
WDC FDC - at page 7 and 10 the adjustment is found
The datasheets said 250 ns for precompensation time for double density - but all sealed drives (i.e. never-touched 1050 drives) I´ve in my hands were adjusted for 230 ns. I think, Atari did this in relation to the slightly lower rotation speed of 288 RpM instead of standard 300 RpM.
And, finally, I found a interesting (sorry: german only) document some time ago at the AtariWiki explained how to make a clone of the 1050. This one also states 230 ns. This document contains the way how to build a 1050 clone using same major chips, but a standard (PC) floppy disk drive - like the XF551 does. It´s written from Bernhard Engl, the developer of the Turbo 1050 speeder. See below. At page 6 the adjustment is found.
Jurgen
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That looks like a nice scope. What are people using nowadays? I think I might retire my old Tektronix 465B
This is a RIGOL DS-1102E, dual channel DSO with a equivalent to 100 MHz analogue sampling rate and seperate trigger input. Regarding price and feature sets, it´s something of higher entry class or lower middle class DSO IMHO. You can pay tenth of money and get more functions, but for a tinkerer like me it´s enough. This model is very popular here in Germany, a lot of people in the electronics-related forums own such a DSO.
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I have a 1050 that I changed the FDC to test and then found the 74LS74 was bad. I guess I should put th3 original FDC back in even though it seems to be working fine? I was thinking about doing so anyway just to make sure it works and, if it does, keep the newer known working one. If the old one doesn’t,t work I will try following the instructions given here.
You should do. Maybe the differences of both FDC are small. And of course the whole thing can accept some tolerances within. But if you know exactly which FDC was installed former, take this one.
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Hi all,
this post is intented as a "How To" short manual for all those who have problems with their 1050, specially when using medium/enhanced density or double density (with Happy 1050, Speedy 1050 and so on). I didn´t found this information here at AtariAge, so I want share this.
Some people purchased Turbo 1050, Speedy 1050 or the Bitwriter 1050 from me and report problems. In most cases the 1050 drives where the new expansion was built-in weren´t extensively tested before, so the conclusion for the owner was: The new expansion is the culprit.
The FDCs (Floppy Disc Controller) 2793 or 2797 used in the 1050 drives needs at some points exact input signals to work properly. These are the 125 KHz rectangled frequency for single density base clock, a 230 microsecond long impulse for precompensation (when using double density, MFM mode) and others. "Modern" FDC like the 1772 (used in the XF551 drive or Atari ST computers) have the needed PLL and synchro circuits built-in and adjusted by the manufacturer. The old FDC 279x need external R/C links to setup the needed frequency and delays.
Two problems now appears:
- Every FDC has tolerances within. Really EVERY piece. Also when you take two pieces from the same batch, same production week etc.
- Every 1050 mainboard may have different manufacturers of the involved capacitors and resistors with their own tolerances
What happens now? Sometimes - specially when you buy any used drive from "anywhere" - the pre-owner (or anybody else) has done some "repair" by changing the parts in sockets (FDC, CPU, RAM, ROM, RIOT) and when he´s lucky, the 1050 works. But when the FDC was part of the changed ones, you get a 1050 drive with wrong adjustment.
The typical issues:
- When the adjustment is absolute out of specs, you can´t successfully format or write to any disk. Reading might be okay
- When the adjustment is nok ok, but not totally worse: Formatting and writing a disc with medium/enhanced/double density fails, but single density works
- At all cases: You might can write format and write a disc with medium/enhanced/double density flawless, but no other drive can read your formatted discs...
So MAYBE your drive need an adjustment. This post doesn´t claim itself as a cure-all, it´s just a possibility. I´ve hat a lot of drives for repair in the last 20 years, where the FDC has changed one time for any reason (and some people change them for a test, but not change them back...)
How-To adjust the analogue part for FDC´s frequency setup:
- Open 1050, remove drive mechanic
- Remove (if necessary) any speeder PCB. You need free access to the FDC and approx 1-2 cm around it
- Switch on the drive and let it warm up (chips) for 5 minutes
- Warm up your scope
- Close TP7 and TP8 with a jumper. This forces the FDC to enter it´s self-test mode. We need this mode to make the signals visible. See the picture below, where I made a square around TP7 and TP8:
Now put your scope´s probe to pin 16 of the FDC. When test mode is enabled, this pin shows a square waveform with a frequency of 125 KHz or pulse width of 4 microseconds (uS):
If your measurement doesn´t match, use the variable capacitor (marked with "3" in my last picture at the end of this post) to set it to 125 KHz / 4.0 microseconds (uS).
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Next step is pin 29 of the FDC. At this pin you should get a single positive edge with a timeframe of 1.0 microseconds (uS):
When your result is different, use the pot marked with "1" in my last picture at the end of this post to adjust this value.
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The last step is specially needed for double density (MFM) operation. Check pin 31 of the FDC, you should get a single positive edge with a length of 230 nanoseconds (nS):
To adjust this signal, use the pot marked with "2" in my last picture at the end of this post.
That´s all! Don´t forget to remove the jumper crossing TP7 and TP8
(otherwise your drive remains not usable and you´re wondering...).I hope somebody found this useful - at last to be sure that your drive is working with the right setup
Jurgen
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Looks like I have to recalculate, I forgot the seller listed the specs in the ebay description... Looks like I burned out the red on one of these, but the green is still OK.
Looks like I need to buy 100ohm for 5V-->3.0V?
Don´t make it so complicated
The values provided by the LED manufacturer are MAX values you should "offer" the LED to consume. Most LEDs are lighting up with much less power. I use something around 220...400 Ohms for 5V voltage and LEDs of any kind. It´s enough to make them light up and also enough limitation to keep the LED from consuming too much power.
When you want to use it for a write protect switch, take a dual color LED with common anode and connect the common anode using one resistor of 220...400 ohms to +5V. The both cathodes can be used with a DPST switch - one position of the switch (where the RED side is for example) is connected in parallel to pin 2 or 3 of the 74LS02 chip. This NOR gate (it´s output) is connected to WPRT of the FDC. By default (no connection is made) the resistor R51 (20k) keeps the floating input at high level - what´s LOW after the NOR gate - disk writing is denied. When you set this input to low by the switch, writing is allowed. This way needs only 3 wires, no other chips, no complicated stuff.
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Mike Albaugh (interview) gave me a disk of DOS 3, but it's not the DOS 3 that was released by Atari. This might be a planned DOS 3, very different from the thing that Atari released
I´m still very surprised what comes to light today - nearly 40 years after the first bytes of code are made for our Atari 8 bit computers!
WOW!
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What would be needed is to deassert RD5 if A12 is low (which is when accesses hit $A000-$AFFF)
So essentially RD5 = A12. Though unsure if that'd need to be buffered or you could just tie the 2 together.
Won´t work without decoding the whole address space - otherwise RD5 will be high at all times A12 goes high (and vice versa).
Also you would need a seperation by non-inverting driver chip (74LS06 for example or a transistor), then RD5 is pulled-down via 1k to ground at any XL/XE. This would make A12 at the CPU´s buss inoperable.
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Oh well... an Atari ST! I always thought the ST series is extincted in the U.S.
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Actually, 5.25" HD disks typically work at 300 Kbs, not at 500 Kbs, and are normally formatted with 15 sectors, not 18. That's why the hold 1.2MB instead of 1.44MB.
Oops, you´re right. I was thinking about 3.5" this time
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That huge window into $D5xx seems to me that it will have serious hardware incompatibilities. How about ONE register for bank and another for on/off? Better yet, one register and write $FF to it to turn it off. Any other number is a bank select.
Just to give a statement: I don´t want to reinvent the wheel nor make a new flashcart - we have already ENOUGH solutions (The!Cart, Ultimate Cart, UNO Cart, AVG etc.).
Also this is NO competition to the AtariMax flashcarts. Steven makes good items for a good price.
My primary goal was simple: I have some compilations of 16 KB ROM images (31-in-1 or 63-in-1), some "KOMA" images and more. All these need 16 KB switching mode. Some guys ask me to make carts of them for private use. So I create this PCB. And because I think, this is a little bit less, I add the AtariMax 8 KB switching mode also.
I´m a fan of the old brown cart shells with metal plate on their back. I like the AtariMax shells, too. So this PCB fits in the brown carts. I won´t make a huge project, if somebody wants the PCB, no problem, but it may be keep simple.
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I am not disputing this, I am the farthest from a hardware guy. But how was it possible for the 1050 to do 26 sectors @ 128 bytes (as opposed to 18)? Did they basically write data at "double density" rate, but somehow manage 128 byte sectors because they only had RAM in the RIOT?
When "Atari Single Density" (18 sectors per track @ 128 bytes per sector) is used, the FDC (Floppy Disk Controller @ 1050 drive) is set to technical "Single Density" using FM recording at 125 KHz bitrate.
When "Atari Medium / Enhanced Density" (26 sectors per track @ 128 bytes per sector) is used, the FDC is set to technical "Double Density" using MFM recording at 250 KHz bitrate.
"Atari Double Density" (18 sectors per track @ 256 bytes per sector) uses the same setting like "Medium Density". And, just for the records, "HD" mode (5.25" and 3.5" drives) uses MFM with 500 KHz and (by MS-DOS default) 18 sectors with 512 Byte each.
The limitation of 18 sectors using 256 bytes each sector and "real" double density is made to make the floppy disc´s access reliable. The outer tracks (track 0) could be hold, I think, something around 22 or 23 sectors in maximum, because there´s more physical space each track than the inner track (39). In the early years some 5.25" drives exists which such special formats - some of them also change the rotation speed in relation to the track number (head position) - the legendary "Victor 1" PC made such a thing, sounds very unique
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Hi all,
thanks for tipps and suggestions. IMHO there´s no need for incremental or partial flashing. I would go that way: Erasing the whole flashchip, start from $00000 and go on until file ends. So a "31-in-1" game cart file with 512 KByte (16 KB mode) will also work instead of using a 63-in-1 (with 1 MByte in 16 KB mode).
I never own a 1 MBit (128 KByte) AtariMax FlashCart. Does these carts also start with bank 0? I remember something special with that ones read here a long time ago.
Jurgen
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Hi,
I´ve made some time ago a little project, but haven´t found the time to finish it. The hardware is ready and works fine, but the important thing - the flash utility - is not ready. And without a flashtool this PCB is useless.
So I´m looking for somebody who agree to write the flash utility for this little piece of hardware. I´m not the best 6502 coder, and, I need too much time. I have so much other ongoing projects - I would be afraid that this project will never be finished.
The special thing about this PCB is that it fits in the genuine brown Atari cartridge shells with metal plate on the back. It can be switched between 8 KB mode and 16 KB mode. Banks are selected by address lines, so an access to $D500-$D57F would select bank 0...127. Any access to $D580-$D5FF switches the cart off. This is the same scheme (for 8 KB) like AtariMax did. So you can use this PCB in two ways:
- Flashing a 1 MByte (8 Mbit) AtariMax Workbork Image to it
- Flashing one of the several ROM compilations floating around (mostly "63-in-1" called) using the 16 KB mode
Write-access can be denied by removing the "WRITE" jumper. For bad flash processes the DISABLE jumper can be set during power-on to prevent the computer from locking while start-up if the flash-ROM content is bad.
So the job to do is coding a flash utility for the Hyuandai HY29F800BG flash chip (it´s 1 MByte x 8 selected, this flash can be accessed in 8 or 16 bit). I would prefer a solution doesn´t require a memory expansion, should be possible, because this flashchip is very versatile in programming.
Of course I would provide 2-3 fully populated PCBs free or charge and shipping with an example content (flashed before with an external programmer)
Anybody interested?
Jurgen
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I used the order based on this schematic and others.
https://www.atarimax.com/jindroush.atari.org/data/ahard/xlwiring.gif
The order in the schematics is not the same like on the mainboards. Look into the Sys-Check manual, there´s a picture of the different mainboard variants with the correct order.
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Programming the Atari XL/XE
in Atari 8-Bit Computers
Posted
Yeah, sometimes real life is annoying