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MarkO

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Posts posted by MarkO

    Tandy Color Computer Cartridge Questions

    in Tandy Computers

    Posted

    So I plugged my Multi-Pak Interface into my CoCo 2, then Powered it up, then the CoCo.. All seems fine. I did the PEEK Test mention at Cloud 9. And got a "255", ( which is the same value you get if there is NO MPI plugged in... ).

     

    I then powered it ALL OFF, plugged in my Three Cartridge Games, StarBlaze, Color Baseball and Demolition Derby. I could switch between the Cartridges and Press RESET and Boot each one.. ( I still haven't plugged anything into Slot #4 ) It looks like I just need the PAL update and I should be Good to Go!!!

    ASM Development Tools for the Coco3

    in Classic Computing Discussion

    Posted

    That is a nice disk system. The drive in that fd-500 case is a single sided drive. Fine for RS-DOS games and programs but you'll want to replace it with a DSDD 360K drive if you start using OS/9 - Nitros9.

    Just recently I got a 26-3022 Disk Controller, that I modified with the Fujitsu MB8877A chip and a FD-500 with very little use on it.. I figured I could move the Single drive from this FD-500 with the J&M Systems Controller into the first FD-500, then get a Pair of Double Sided Drives to Put in the new FD-500.. Then I would have a Drive for each CoCo I have..

     

    Do you know much about the J&M Systems Disk Controller?? I have seen comments about it being not compatible with various Applications and it formats the Disks Differently...

     

    MarkO

    ASM Development Tools for the Coco3

    in Classic Computing Discussion

    Posted · Edited by MarkO

    << REAL BIG SNIP >>

     

     

    170 POKE BO+$4000,PT

     

    << SNIP >>

     

    I typed this into my CoCo3, with the 26-3022 and FD-500 plugged into it... I keep getting an Error on line 170.. I tried to change it to:

     

    170 POKE BO+&H4000,PT

    But it still didn't like it...

     

    Any Suggestions???

     

    MarkO

    Tandy Color Computer Cartridge Questions

    in Tandy Computers

    Posted

    Good point, I believe everything from CoCo 2 on was just +5 volts...

    The Book, Tandy's Little Wonder - The Color Computer 1979 - 1991 has on Page 102, the Cartridge Port (Expansion) Connector and Pins 1 and 2, which are -12VDC and +12VDC as CoCo 1 Only.

     

    As far as what can be added... well, since you have direct connections to both data and address lines... pretty much anything you can think of. The super IDE interface is a good example of what can be done, and that adds support for hard drives, cd roms, and compact flash drives.

    I found a reference to a Generic EPROM Board, the CoCoEPROMpak, in the thread, What vintage computer modifications have you performed recently?, Post #26.

     

    Comparing the Apple ][, the C64 and the Tandy CoCo on their Bus Expansion, it is interesting to see the Design Trade-Offs each selected..

     

    The Apple ][ has Seven Slots ( Slot 0 on the Apple ][ and ][+ and the Aux Slot on the Apple ][e are a Special Case ), which each have a Small Memory Mapped Region, uniquely Associated with a given Slot, and a Shared Memory Mapped Region that the Active Slot can Take Over for a period of time.. Each Slot has Access to ALL the Address Lines and Data Line, and Clock Signals.

     

    The C64 has One Connector, like the CoCo, for Cartridges. I have one Third Party Product called the L-Bow, that lets you connect Two Cartridges. I use this for my Epxy Fast Load Cartridge, and then can plug in something else to the Bus. I don't ever recall of Commodore making a Multi-Pak device for the C64. This Connector has Access to ALL the Address Lines and Data Line, and Clock Signals.

     

    The CoCo has One Connector for Cartridges, and the Multi-Pak Interface to Expand to Four Cartridges, but because there appears to be no Memory Mapped locations for Each Cartridge, Only one cartridge at a Time is Active, with the Multi-Pak Interface supporting Software Control of each Cartridge.. This Connector has Access to ALL the Address Lines and Data Line, and Clock Signals. I see there is a Standard for the Disk Controller to be in Slot #4 and the RS-232 Interface in Slot #1. I assume this is so an Application Program, Like Terminal Emulation can know which Cartridge to Activate at a given Moment..

     

    All in All, very Interesting....

     

    MarkO

    What vintage computer modifications have you performed recently?

    in Classic Computing Discussion

    Posted

    The drive needed adjustment, not the controller.

    There was supposedly a bug in the controller that someone had a fix for. I think it just involved adding an IC and some jumper wires but I have no idea where the info is.

    Ahhh... I was confused by the Fact the 26-3022 Controller Card has Three 100Kohm adjustments along the one Card Edge.. The Later Cards do not seem to have them, although they might just be a Lower Profile on the Circuit Board..

     

    If you come across any Fixes for the Bug in the Controller, I would be curious about seeing it...

     

     

    Adjusting the drive is a matter of opening the drive, holding an AC lamp with a regular bulb or a strobe light near the drive and adjusting a pot until the marks on the drive hub appear to stop rotating.

    I have seen pictures of the Original Apple ][ Drives, made by Shugart that have those Timing Marks..

     

     

    I always use the VERIFY DRIVE SPEED feature of Copy ][ Plus 5.5. You install a Scratch Disk, it moves the Read/Write Head to track 35 and Writes a bit pattern, then Reads it back, while timing it.. Your Disk ][ should be at 200ms, Plus or Minus 2ms. A Multi-Turn Potentiometer is on the Spindle Control Board, and is adjusted to get your Spindle Rotational Speed correct...

    ASM Development Tools for the Coco3

    in Classic Computing Discussion

    Posted

    He was talking about the mythical hidden 256 color mode which was accessed differently than other modes.

    Yes, I was....

     

    It would require more hardware to treat it differently so I would tend to agree that it could be paged but there is no guarantee.

    Since nobody has ever actually got it to work I don't think we can assume exactly how it works if it's even in there.

    Maybe it will take X-Raying the GIME to follow all the Gates and see where the Hidden Mode is....

     

    Paging video RAM isn't that difficult, I'd say it's more of an annoyance.

    Anyone that has displayed anything on an Apple II screen in assembly will consider paged video RAM to be easy. :grin:

    Page flipping is the Old Standard to get Nice, Smooth animation on the Apple ][.. Flapple Bird is using the Vertical Blanking to get Nice, Fast, Smooth animation..

     

    The font routine I wrote for the VZ series (modded to use hi-res) only has to deal with 2K pages but it's the same principal.

    The CoCo 3 MMU is slightly more involved but nothing horrible.

     

    The biggest complaint I have is that it's less efficient for drawing sprites, lines, circles, etc...

    What is Less Efficient?? Page Flipping?? or the CoCo 3 MMU???

     

    MarkO

    ASM Development Tools for the Coco3

    in Classic Computing Discussion

    Posted

    << SNIP >>

     

    Also, all video modes can define where video ram is, so with a few pokes, you can create page, make a few pokes to point the video there, then work on buffer 2, when done, flip the video ram there and go back to buffer 1 and modify that while buffer 2 is displayed.

    That is a very cool feature of the CoCo. Is the Video RAM configurable in all the Models, or just the CoCo 3 with the GIME???

     

     

    MarkO

    ASM Development Tools for the Coco3

    in Classic Computing Discussion

    Posted

    All of the MMU control registers and Video mode registers are reachable via EDTASM+, you can control what mode, 2 or 3, any one of 22 graphics modes (both old and new), and you have up to 64 8k banks, any 8 of which can be active. As long as you don't bank out the bank your code is running in, you're fine.

    If you think of Modern Development Systems, that contain Libraries or Modules, it could happen that the older versions don't support a newer feature..

     

    I concur that a Strict Assembler, it won't matter.. EDTASM+ won't support the Hitachi 6309, unless you get the Patch from Robert Gault.

     

    MarkO

    Tandy Color Computer Cartridge Questions

    in Tandy Computers

    Posted

    Yes, I went back and looked at that article, and Pin 8 is the CART* Cartridge Interrupt detect line. Taped over, it can be inserted into to the CoCo, and when you turn on the CoCo you'll boot right to Extended Color Basic.

     

    Everything you always wanted to know about a CoCo cartridge but were afraid to ask...

     

    Actually this part is incorrect...

     

    ------------------------------------------------------------

    | PIN | SIGNAL NAME | DESCRIPTION |

    |-----|-------------|--------------------------------------|

    | 1 | N.C. | (-12 VDC on CoCo 1 and 2) |

    | 2 | N.C. | (+12 VDC on CoCo 1 and 2) |

     

    << BIG SNIP >>

     

     

    The +/-12VDC is only on the CoCo 1, otherwise the Original 26-3022 Floppy Disk Controller would have worked on the CoCo 2, with out the Fujitsu MB8877A Replacement..

     

    I am looking into this 40 Pin Connector, to see what all can be added...

     

    MarkO

    Tandy Color Computer Cartridge Questions

    in Tandy Computers

    Posted · Edited by MarkO

    You don't have to cut the trace; put scotch tape over the last pin on the cart to disable the boot :) The cart memory will be available, you can manually launch or save the image to tape.

    You don't even need tape if you have a Multipack Interface.

    For flexibility, I would try to replace the Trace with a Berg Jumper.. So I could have it Auto Started or Not...

     

    I found on this Page, Apple ][ Lode Runner for CoCo 3, that Someone, Somewhere, recently has made generic, 28 pin Tandy CoCo Cartridges..

     

    MarkO

    Tandy Color Computer Cartridge Questions

    in Tandy Computers

    Posted · Edited by MarkO

    I don't think there's any bank switching going on, I think I meant to say $C000 to $FF00, 15 1/2 k, with the last 512 bytes mapped to the control registers. Which is cool, because you'd be accessing those registers anyways to change video modes, produce sound, bang the bit banger port, etc.

    In doing more CoCo Research, it appears the GIME in the CoCo 3 can Bank Switch up to 32K of ROM in a Cartridge.. The CoCo 1 and 2 can not...

     

    MarkO

    What vintage computer modifications have you performed recently?

    in Classic Computing Discussion

    Posted

    Drives with controller used to be $50-$75. I have to think that is a temporary jump.

     

    The 26-3022 looks like an original unit. They don't hold their speed very well an you have to adjust them once in a while or they screw up your disks. I've had one since I was in high school and it was a PITA!

    The other model should work with a CoCo controller. I'm not sure if it was a CoCo drive or a Model IV external drive. Doesn't really matter, it looks like a better mechanism than the original. The original has the button on the front you push down on to open the drive.

    Do you have any Directions on Adjusting the 26-3022 Analog Disk Controller???

     

    I have one I bought, and have replaced the WD WD1793B-002 with the Fujitsu MB8877A and connected it to a FD-500 with a single Drive..

    ( See Album Tandy CoCo's 001 )

     

    The 26-3022 Disk Controller was Surplus from the Tandy Surplus Store in Fort Worth, TX, so it most likely new, the FD-500 is very low usage, owner claimed used less then 10 Hours.. It Looks like new, Warranty Sticker still in place and no ware..

    Halt and Catch Fire(tv series)

    in Classic Computing Discussion

    Posted

    I don't recall them mentioning why the clean room BIOS was important.. That being that careful was a New Thing..

     

    After Apple sued Franklin and then IBM sued Eagle, direct copying was known to get you in trouble.. Compaq and Phoenix Technologies were two companies that used two sets of Engineers to make a clean BIOS..

     

    I noticed a few little mistakes here and there, but the total amount of "jargon" is fantastic.. I really wonder if people that haven't lived through these events are following most of the conversations.. Sometimes the conversation moves pretty fast.. for me its a refresher..

     

    MarkO

    ASM Development Tools for the Coco3

    in Classic Computing Discussion

    Posted · Edited by MarkO

    Well Mark, I think you can safely assume you're the LAST LIVING HUMAN BEING TO UNBOX A BRAND NEW COCO 3 !!!!!! Would have made a great "unboxing" video for YouTube, if I had it, I would have recorded it and posted it to YouTube and sent a link to Tandy!

    I though about it, but the Box Seal was broken and a hole ripped in the Box, the Main Unit had been unwrapped at some point, but the Original Owner, had never plugged it in or powered it up.... Still Lost is the Piece that was shipped later to the Original Owner, noted as Missing in the CoCo 3 box... ( See These Photos )

     

    If you're all Gung-Ho to replace the CPU, then you must have read the story about the Hitatchi 6309. I guess the story was that Hitachi wanted to make a better version of the 09, but Motorola would only license them to make an exact clone. Apparently Hitatchi went ahead and made the better chip anyway, and just didn't document the extra features. Years later, as CoCo's needed servicing, alot of hackers would replace a blown CPU, and some used the 6309, and, as hackers go, some started tinkering with it and found by testing "unused" bits that there were extra bells and whistles in there after all. This spawned a craze in the community, and lots of users have since done the upgrade. I even think there are some kits out there with instructions on how to go about doing the upgrade.

    The hardest part is removing the Old 6809 chip... Luckily I do quite a bit of Through Hole and Surface Mount Rework at my Day Job..

     

     

    At the bottom of the page is a zip file with all the info for doing an RF to Composite conversion for the CoCo 2. The reason the CoCo 3 had composite output was because scores of people were doing the conversion so they could use either a TV with composite inputs, or, another popular thing to do at the time was to buy the Commodore 64's 1702 composite monitor, which was a really nice, high quality composite monitor for use with the C64.

    Thanks for the Link... Previously I found a Link to a Sinclair ZX81/Timex-Sinclair 1000 page that showed how to Bypass the ZX81/TS1000 RF Modulator and get Composite Output.. I figured the CoCo 2 would be very similar... The Apple ][ had an Issue with the RF Modulator, so they Gave it to another Business to Make, and Sell.. See, http://www.apple2history.org/history/ah03/ , search for "Sup’R’Mod"

     

     

     

    One of the great things about the CoCo is even today there's a large number of vintage users who either, like me, had one way back in the day and just couldn't let go, or in recent times, discovered vintage computing and found the CoCo.

    I am that way about the Apple ][, had One ( actually Two ), back in the Day, and now am getting back into them..

     

     

    Another cool thing about the CoCo 3 was the GIME chip. Tandy was worried that if they made the CoCo 3 too good, it would hurt sales of the Tandy 1000. The Tandy 1000 had EGA graphics, the bleeding edge of PC graphics at the time, and Tandy intentionally held the CoCo 3 to 320x192x16 colors (palette of 64) and 640x192x4 colors. EGA was 320x200x256 with a 256k palette. The thing is Motorola had designed a 256 color mode into the GIME chip, but Tandy wouldn't allow it, so it's there, but undocumented. Some research on this last secret of the CoCo 3 has been done, and you can find further info about it here:

    http://members.optusnet.com.au/nickma/ProjectArchive/256mode.html

    Thanks for this Link too... Very Interesting Reading...

     

    I have seen references to the 256 ( and 240 ) Color Mode.

     

    Overall, the 6809/6309 looks like a really nice 8 bit chip.. I am excited to try programming it at the Machine Language level..

     

    MarkO

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