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MEtalGuy66 last won the day on October 17 2009

MEtalGuy66 had the most liked content!

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About MEtalGuy66

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    River Patroller
  • Birthday 10/19/1973

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    If it aint broke, fix it anyway!
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    Houston, TX, USA
  • Interests
    ATARI XL/XE hardware repair, ICD Multi I/O reproduction/development, SpartaDOS, MAC/65, BASIC XE, ATARI TELNET BBSes and related hardware, AMIGA 1000/500/500+, preservation of the 5.25" floppy as a standard for 8-bit computers.

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  1. Those are bad-ass, Calimero. You have my total admiration for the dust covers.. The yuppie-assed "feng shui" type presentation environment, not so much.. But the covers themselves.. Righteous, man..
  2. If you hook an external 5VDC PSU to J7, the regulator and rectifier will be bypassed and the MIO will run much cooler. If its a 1meg model, make sure your PSU is capable of doing at least 1A sustained, preferably more.. You'll have to rig an inline switch if the PSU doesn't have one, because this also bypasses the power switch on the MIO. This is what smart BBS sysops did back in the day after realizing that even extra fans wouldn't save the MIO's pitifully underrated PSU components from eventually cooking themselves, during 24-7 sustained useage.. J7 pinout: 1&2 9VAC circuit (do not connect anything here) 3&4 9VAC circuit (do not connect anything here) 5&6 GND 7&8 5VDC note: make sure your MIO has the 5V PLL upgrade. In other words, it has to have the newer U19 IC that runs on 5VDC. Otherwise, you will need an additional 12VDC supply to pin 16 of U19. If your board is missing VR2, then it has the upgrade. If VR2 is populated, then it does not have the upgrade.
  3. The Apple II doesn't do 280x192x 6 colors.. It's 290x192 monochrome pixels in HI RES. The color pixels are effectively artifacts so it's only actually 140x192x6 colors.. In double hi-res, you can have 560x192 monochrome pixels, or effectively 140x192x16 colors. The apple has the ability to turn off the chroma signal to the composite video output when in text-only screens, to avoid the color artifacting. and thus utilize the full monochrome resolution for text, but in hi-res graphics modes, with a color composite monitor, you are going to see the color artifacts whether you like it or not. You can plot pixels on the full resolution of the bitmap, but you are actually only going to see 140 color artifacted perceivable pixels horizonatally..
  4. Prince of Persia Wings of Fury Bard's Tale series. Wizardry Series.. Legacy of the Ancients
  5. Total bullshit, I'm afraid.. All that is required is setting the register to 0.. Like I said before, it's done pretty commonly on apple IIc, apple super serial cards, etc.. for fast serial transfer of disk images on the apple II.. And there's no switch involved.. And on those implementations the chip is also clocked at 1.8432mhz.. Its pretty standard..
  6. It's already running on a 1.8432Mhz external clock.. There's a big assed 1.8432Mhz crystal right there next to the chip.. On both devices.. And yeah, it can be done in software. ADTpro on the Apple II does this using the 6551 based serial ports..
  7. The fastest data throughput you can get from a 1.7mhz 6502 is about 200Kbytes/sec. You can subtract from that any cpu time and propogation delay caused by software/hardware handshaking.. But theoretically, you could could probably do over a megabit/sec if everything was reasonably well implemented. What would be the point? No standard RS232 device operates at that speed. I think that something like the Fujinet on PBI would fill/replace many roles. As far as crisp 80 columns, get a VBXE and a 14khz capable analog RGB display.. As far as the nonstandard MIO DB9/DB25 ports.. I hear ya.. I corrected them on my reproduction MIO board design. There are at least 35 MIOs out there somewhere that have PC-standard serial & parallel ports..
  8. Usually, the diodes get so hot that they delaminate the copper traces from the PCB, burn off the green soldermask, and even turn the fiberglass of the board dark brown/black.. Before finally prematurely failing due to obvious over-heat (over-current and lack of cooling) conditions. The large aluminum plate is adequate heat-sink for the 7805 regulator, but I have seen those fail too. If you want to fix the power circuit back to factory functionality, just replace the 7805, diodes (Id go much bigger or use a 2A+ rated bridge rectifier unit instead,) and the 3 largest electrolytic caps (these are probably dried up and shorted with age). If you send me a pic of your board in PM, I can make further suggestions.
  9. The 1090 was dropped before the modern XL/XE existed.. By the time the 800XL and 600XL were finalized, ATARI's current product development dept. had resigned themselves to a)producing the XL line cheap enough to compete with the C= 64 price point and b)only using the PBI port for a memory expansion for the 600XL. Any 3rd party developers wanting to use the PBI bus for complex expansion devices basically had to deal with any problems incurred on their own. The last machines that had a buffered expansion bus were the 14xxXL line. And even some of that was never standardized. The 1090 has provisions on the board for full buffering, but it can be assembled to bypass it. I have seen 1090 prototypes built multiple ways, in this respect. I'm not sure of the level of functionality/stability any given spec had in this regard. They were ALL still prototypes and limited promo/beta/show units. Anywayze, the main point is that Atari originally envisioned the PBI as a workable expansion system, but it got bastardized before it ever saw consumers' hands.. Sad but true.. When the XE line came along, there were a whole new crop of people at ATARI (both engineering and marketing). The ECI bus was basically just a more centralized/complete connection standard for what had been the "XL PBI PORT" (and a few additional choice signals) so as not to "close the door" on the possibility of more 3rd party local bussed expansion hardware, but also to reduce costs even further by making the cart port and "ECI" physically overlap.. Even in the XE era, ATARI, itself had no intention whatsoever of selling a complex parallel-bus connected device.. They knew the stability problems (and related support nightmare) that would cause. Hence the ridiculous nature of the XEP-80 80 column "solution".. Both ICD and CSS had "custom tuning" departments that required you to ship them your ATARI so they could hook it up in conjunction with the device (MIO or Black Box) and make necessary timing adjustments (add caps.. Swap ICs.. etc.) to various circuits in the event of stability issues that could not be resolved by normal user operator means. Most cases of this involved heavily expanded machines, but not all. You can read about a lot of these cases on the old Compuserve, Genie, and usenet archives from the late 80s to mid 90s.. The last thing that's worth noting here is that in recent decades, a lot of people (Candle, HiasSoft, Mega-Hz, Simius, Warerat, myself, and others) have all tried to come up with a somewhat universal "PHI-2 timing fix" that would address these stability issues in a way that would negate (or at least reduce) the amount of "custom tuning" needed to achieve/maintain stability on an ATARI with a heavily expanded parallel bus. To my knowledge, there is no universal system-wide fix.. There are device specific solutions that can be added to hardware designs which will augment the PHI2 timing in relation to the onboard chips on that device.. But there is still the possibility (Heh. Probability) of the total bus load/capacitance effecting the PHI2 to bus timing with respect to the Atari's internal chips and causing flakiness in many cases. The more bus capacitance (the more crap you've got connected to the system's physical bus), the more likely/prominent this is.. So.. This, I'm afraid, is simply the "nature of the beast" with these systems... And as I said, it's all about cost reduction back in the 80s. For contrast, Apple II is a good example of a 6502 platform on which a relatively stable expansion bus standard was developed..
  10. The lack of a proper buffered expansion bus on the atari 8bit platform means that anything connected to the data bus skews the bus capacitance/timing all to hell and creates flakiness & instability. That is the problem with developing for PBI. The PBI standard, itself is very straightforward. This is not a unique problem n the 8-bit world. The C=64 is in no better shape in this respect. It was all about cost reduction..
  11. Obviously I wasn't comparing a floppy drive emulator to the MIO when I specified "mass storage". SIDE2/3 is very stable now, works reliably, is much faster, and much cheaper. If you don't need local-bus speed, SDrive, SIO2SD, Fujinet, etc.. are all good options. I do prefer IDE Plus 2.0, although I am not aware of how/where it is still being sold. The MIO is a dinosaur. The design is based on alot of older generation power hungry ICs and it is extremely temperamental and succeptable to bus-load/timing related instability issues. Also, compatible drives are hard to find and/or expensive. It's not a real SCSI interface. It's missing an output that all but the most archaic SCSI operation modes depend on as a key part of the interface. Even modern devices that work via the firmware updates we did, do so as a result of their firmware supporting this archaic mode of operation. It's kind of "in between" SASI and SCSI-1, strandards-wise.. There's also the fact that it isn't a legal PBI device and hogs the PBI interface almost exclusively.. Let's see.. The original ICD design has pitifully inadequate heat dissipation on the power circuits.. The rectifier diodes cook themselves, along with the PCB.. ESPECIALLY on 1meg models.. I'd much rather have a device that works with ~90% of storage devices you can plug into it... Doesn't need to be fine-tuned based on bus load/capacitance/timing skew in order to reliably operate in a system with other expansions.. Can actually work with other PBI devices on the same bus... Is not a fucking HEATER.... It was fun to play with back in the day when we didn't have much better/cheaper options. Now, it's a collector's item..
  12. Yeah. We don't build those any more. At the time we did, there were very few mass storage solutions available for the ATARI 8 bit. Now there are many that are much cheaper and better in every way than an MIO. Here are a few: https://lotharek.pl/products.php?id=41 https://www.vintagecomputercenter.com/
  13. F*ckin awesome.. Took them 35 years to port it from Atari 8-bit to PC.. Guess the PC hardware has finally evolved to a state that it can handle it. 😆 Should port it BACK to atari 8-bit, but utilize Rapidus and VBXE..
  14. You know.. After collecting my thoughts on this subject.. Here's what I will say, as I'm sure Flashjazzcat will agree, it's probably the most relevant point concerning this topic: Alot of people have great love for the look, ergonomics, and keyboard of the 1200XL.. Years ago, you couldn't do things like "separate antic & CPU access to extended banks" in DIY mods without extensively additional wiring & assembly of discrete logic.. You certainly couldn't even dream of things like a meg of ram in 2 chips on a single small upgrade board that goes in any Atari with only a few wires to hook up. So back then it made a lot of sense to start with the motherboard that was closest to the "end product". Thanks to the huge increase in availability, economy, and scale of programmable logic devices, and the hard work of people like Candle, Lotharek, Mega-Hz, Simius, Flashjazzcat (and many others that I apologize for not mentioning,) the situation has changed tremendously in the last 2 decades. There are quite a few easy options for these, and many other previously "formidable" upgrades these days. It matters much less which XL/XE motherboard you start with these days, from a mod installation complexity standpoint.. For me, the PBI is still the deal-breaker for the 1200XL board, but others may be happy with the alternatives that Flashjazzcat mentioned. And if you are willing to do a "motherboard transplant" then why not go with something truly bad-ass like the Eclaire XL?
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