Tag: video

TI-99/4a FAQ

Initially I will be cutting and pasting the FAQ from the atariage forum. I’ll be updating this one then referring people here from the forum in the future once it’s complete. – Greg

Table Of Contents:

TI-99/4a and related Web pages
Users Groups
User meets/festivals
Emulation Section
Vendors
Frequently asked questions

TI-99/4a and related Web pages:

Users Groups:

User meets/festivals:

USA:

  • Chicago TI Fest: TBD – Evanston Public Library, 1703 Orrington Ave, Evanston, IL 60201
    • Chicago TI Fest Companion Gathering: TBD https://atariage.com/forums/topic/287013-chicago-ti-friday-2019-companion-gathering-to-chicago-ti-world-faire/
  • TI Fest West: sometime in 2021 – TBD
  • Vintage Computer Festival Pacific Northwest – cancelled due to virus
  • Portland Retro Gaming Expo: Portland Retro Gaming Expo  https://www.retrogamingexpo.com/admission.php  also cancelled due to virus

Europe:

  • The German group will meet in Vienna (Austria) for 2020. It will take place from October 2nd to 4th (Friday to Sunday).
  • The Dutch group will meet on 14th March 2020 in Den Haag, Netherlands.
  • The British group will meet for their AGM on 17th and 18th April 2020 in Loughborough, England.
  • Regionales Usertreffen 4. April 2020 in Mannheim, Germany cancelled due to virus

More info: https://atariage.com/forums/topic/299877-ti-europe-events-2020/

Emulation Section:

Windows Emulators:

Linux Emulators:

DOS Emulators:

Multi-platform Emulators:

  • Mame/MESS: http://mamedev.org/ (emulates every version of the 99/4a, the Geneve, 99/8 and more!)
    • https://www.mizapf.de/en/ti99/mame for TI and Geneve MAME support from the current maintainer Michael Zapf
    • https://atariage.com/forums/topic/313851-ooeygui-v40-released/ The great java based front end for MAME that auto installs the latest TI-centric version and all the support files including carts, disks and roms
  • Java V9t9: http://eswartz.github.io/emul/

Web Browser based Emulators:

JS99er.net: http://js99er.net/

Emulation File Formats:

  • TIfiles file
    • TI Files was the first representation of a TI file in emulation or on a foreign file system. It contains the same information as the file on the TI but also includes a 128byte header (that we only use 16 bytes of) to contain the TI directory information. The original Xmodem implementation by Paul Charlton on the TI attached this header automatically so when you uploaded a file from your TI to some other type of computer (BBS) you could download it again without having to do a conversion or uuencode.
    • TIPI, HDX & Classic99 both support this file format
    • http://ti99-geek.nl/Doc/Ti99_dsk1_fdr.html and https://www.ninerpedia.org/wiki/TIFILES_format for more technical information.
    • TIFILES File Header
	Byte	Content		Comment
	0	0x07			Contains the length of the TIFILES string
	1-7	'TIFILES'			Contains the literal string 'TIFILES' by means of identification
	8-9	Length in sectors	Number of 256 byte sectors of the file, big endian
	10	File type		Not the same as the PAB
		Bit 0			Fixed (0) or Variable (1)
		Bit 1-3			Not used
		Bit 4			Protected (meant to prevent copying, largely ignored by 3rd
					party software.)
		Bit 5			Not used
		Bit 6			Display (0) or Internal (1)
		Bit 7			Data (0) or Program Image (1)
	11	Records per Sector	number of records per sector for record based files
	12	Bytes in last sector	Used to determine the true end of the file (0 indicates 256 
					bytes in last sector)
	13	Record length		The length per record, as in the PAB
	14-15	Number records	Number of records in the file if fixed, or number of sectors
					in the file if variable. Little Endian, which is unusual for the
					machine and inconsistent with the length field!
  • V9t9 File (FIAD)
    • This is the most common emulator file format, it is simular to the TI Files format above in that you can store TI files in a foreign drive format but access them on the TI just like they were native.  V9t9, Win994a, HDX and Classic99 all support this format.
  • V9t9 disk image (DOAD)
    • this is a “sector dump” of the TI disk
    • Supported by Classic99, V9t9, Js99er, Win994a and MAME/MESS.
  • PC99 Disk image
    • PC99 sector dump of the TI disk
    • Supported by PC99 and MAME/MESS

Disk formats

On the TI basic has no idea what a disk drive is. It’s the DSR in the controller that gives basic, or other software the ability to use disks. It is basically plug-and-play in 1979, pretty impressive.. Make a new storage device? basic doesn’t care, just as long as the DSR is there.  So most disk formats are logically based on the controller you have.

Ti Disk Formats 

    • 90k ss/sd
    • 180k ds/sd ss/dd
    • 360k ds/dd 40 tracks

TI disk controllers:

  • Texas Instruments Disk controller Sidecar
    • SS/SD 90k
  • Texas Instruments Disk controller (PEB)
    • SS/SD 90k
    • DS/SD 180k
  • Myarc Disk Controller (PEB and sidecar)
    • SS/SD 80k
    • DS/SD 180k
    • SS/DD 180k
    • DS/DD 360k
  • Myarc Hard Floppy Disk Controller (HFDC) (PEB)
    • SS/SD 80k
    • DS/SD 180k
    • SS/DD 180k
    • DS/DD 360k
    • DS/HD 1.44mb (Geneve only HD with 32k ram chip and 9216B installed on the HFDC)
  • Corcomp Disk Controller (PEB and sidecar)
    • SS/SD 80k
    • DS/SD 180k
    • SS/DD 180k
    • DS/DD 360k
  • BWG Disk controller (PEB)
    • SS/SD 80k
    • DS/SD 180k
    • SS/DD 180k
    • DS/DD 360k
  • NanoPEB/CF7 (sidecar) disk emulation formats supported
    • SS/SD 80k
    • DS/SD 180k
    • SS/DD 180k
    • DS/DD 360k
    • NANOPEB 800k (note: No native TI disk controller supports the nanopeb disk size, you’ll have to copy the files to a disk with a format that is supported.)

Disk Managers:

Since the storage software on the TI is DSR based there needs to be an application to format disks, copy files, duplicate disks etc..

  • Texas Instruments disk manager programs
    • Disk Manager cartridge
      • supports only the format that the TI sidecar supported SS/SD
    • Disk Manager 2 cartridge
      • supports only the formats that TI supported on the PEB DS/SD controller..
    • Disk Manager 3 cartridge (prototype)
      • supports DS/DD for the unreleased DS/DD controller
  • 3rd party disk manager programs
    • DM1000 was released from the Ottowa users group in the 1980s and can format up to DS/DD, special versions were created for many hardware devices including the Gram Kracker, Horizon Ramdisk and Cf7/Nanopeb.
    • DM2K is under current development and is updated regularly. It can do 40/80 track DS/DD.  current version is 3.0 and it’s the most versatile disk manager  www.ti99-geek.nl/Projects/dm2k/dm2k.html
    • GDM2K was released to give DM2K functionality on the Geneve in Mdos mode.
    • Corcomp Disk manager was included with Corcomp controllers and could be loaded from the title screen with the stock ROMS
    • Myarc Disk manager was included with Myarc controllers

Disk Emulation:

  • Gotek
    • Gotek drives are inexpensive and available most places including arcadeshopper.com
    • USB flashdrive stores your images
    • Stock Gotek firmware will NOT work with TI and Geneve however,
    • Gotek has been tested with 3rd party firmware on the TI and Geneve (see below)
    • Firmware options: 
      • Flashfloppy firmware – This is the most versatile firmware.. and it is free
        • Supports a massive range of retro computers, synths, and machinery
        • Directly reads and writes many image formats
        • Flexible track layout for Raw Sector Images
        • Extremely configurable
        • Supports TI DOAD (dsk images) directly without conversion and also can use HFE format files
        • many hardware addons including speaker, various displays, rotary and other encoders for selecting disk images
      • HXC firmware 
        • all TI disk images must be converted to HFE format to be used
        • $ per drive to install
  • http://hxc2001.free.fr/floppy_drive_emulator/
    • Cost varies but is around $115 + shipping from EU
    • available in SDCard and USB models
    • all TI disk images must be converted to HFE format to be used

Vendors:  

http://www.dsapsc.com/what-is-sid.html – SID99 add a SID soundchip to your TI

https://dnotq.io/f18a/f18a.html – F18A vga VDP replacement

https://shift838.fwscart.com/ – Geneve keyboard adapters, drive select boards, geneve scart adapters and more

https://www.arcadeshopper.com/ – Software, Hardware, Cables and adapters. TIPI, Flashrom99, SAMS, USB Keyboard adapters, Extended Basic 27 suite, RXB and much more.. new games, multi-carts etc

FAQ:

 

 

 

  • I don’t have a cassette cable to store/load programs how do I get one?

  • Can I use any cassette drive/audio source?
    • In short Yes you can. As long as the volume is loud enough.
    • There is an official TI program recorder but it is a standard audio cassette player, any player with the proper connections (mono audio out, mic in and remote) will work with the TI. Good tips on that link for setting up your recorder with the correct volume etc..
    • I have had success with a stereo to mono splitter on my PC and playing WAV files out using VLC to my TI as well.
    • Need some software?
    • Get a Expansion Box, TIPI or Nanopeb and use disks instead.. (see below)

  • What are the best games for the TI-99/4A?

    • The best games are usually run in 32k from disk or use a large rom cartridge such as the 512k cart or the FlashROM99 or FlashGROM99 cartridges. Expansion RAM (32k) is a requirement for most modern home-brew games/demos.
    • The TI Gameshelf contains a database of all kinds of games including games that run from TI-Basic, Extended Basic and Assembly Language games that require a disk system and 32k. (see website links at the top of the FAQ)
    • There is a great game high score contest on the atariage forum that we showcase some of the best games for the 4/a every month and the winner of the high score contest usually wins TI software or hardware donated by the last month’s winner.
    • Rasumus and Sometimes99er are the most prolific home-brew game makers as of late and their software is featured here in the development forum. Cartridges for most of these are available at arcadeshopper.com.

  • What do I need to load assembly language programs?

    • The big requirement is RAM, assembly language programs need the extra 32k to load into since they are programmed for that memory space.
    • The basic playground loader uses the teeny amount of cpu RAM in the console to leverage loading assembly in Ti basic but that’s limited to very small programs. Ti basic has no built in ability to access expansion RAM.
    • Most games from TI on cartridge for instance are written in GPL and run from GROM carts. They can be copied to RAM and run from there but it has to be the 32k expansion RAM. This is how we run GROM games from a ROM cartridge board such as the flashROM99.
    • Editor assembler gives you the loader to load assembly programs. Editor assembler sets up a environment with routines that can be called by programs. It also has add on routines for Ti basic while the cart is installed. Both require 32k expansion RAM to do this.
    • Extended basic gives you the ability to load SOME assembly natively.
    • People have written loaders for extended basic that create the editor assembler environment that many programs require to load correctly.
    • These days with sidecar 32k availability for a reasonable price and SAMS cards for less than $100us and the FinalGrom99 sd card cart you can have a full assembly language capable TI for not much investment.

  • What is 32k ram expansion and how do I get one? Are bigger memory cards available?

    • The 99/4a came with 16k VDP ram on board. This is memory shared with the Video Display Processor and Basic.  It can not be used for running assembly language or GPL programs. They run from cartridge or expansion memory.
    • 32k ram expansion gives you additional memory for Extended basic, assembly language programs and GPL programs. It also is required for most of the utilities and fun 3rd party/homebew stuff.
      • Editor Assembler requires 32k ram expansion.
      • The 32k can not be duplicated in multiple cards/expansions so if you want to use another device that provides 32k you must remove or disable the existing 32k device.  (this is a issue with the nanopeb/cf7 device as they can not easily have their 32k disabled and so therefore can not share the buss with other 32k ram expansion easily)

How do I get 32k ram expansion? 

 

 Can I get bigger memory cards than 32k?

    • Yes you can get bigger memory cards such as:
      • Myarc 128k and 512k memory card
        • These include the 32k expansion ram and use a proprietary method to address/bank in the additional ram.
        • They also include DSR routines to do print buffering, ram disk etc.
        • With the Extended Basic II DSR ROM installed you can use 128k of this memory in Myarc Extended Basic II.
        • Myarc Extended Basic II is a software package that comes on diskette and requires a compatible Myarc or Foundation 128k/512k memory card, a cartridge with ram at 6000 (supercart) and a disk drive to load the program.
        • EBII is significantly faster than the TI Basic and Extended Basic interpreters and also provides additional functionality such as bitmap graphics and other features.
          • More info: https://www.ninerpedia.org/wiki/Myarc_Extended_BASIC_II
      • Foundation 32k/128k memory card – also includes the 32k expansion ram, These are basically identical to the Myarc card in fact there’s a ROM swap to make it 100% compatible and work with Myarc Extended Basic II (there is also a hack for these to make them 512k) (roms available at https://arcadeshopper.com)
      • AMS – Asgard Memory System cards were available in 128k-512k sizes. These set the standard for AMS memory and were quite expensive when they first came out. (discontinued – rare)
      • SAMS – Super AMS supporting up to 1mb of ram. 32k expansion is included and the rest is only compatible with software that works with AMS (discontinued rare)
      • Ksarul SAMS – The latest incarnation of the SAMS with 1mb or 4mb ram capabilities. Currently only the 1mb version is available.  32k expansion ram is included with SAMS.
      • Sidecar SAMS – Equivalent to the 1mb SAMS pbox cards now in tiny sidecar format with 44pin header compatible with the TIPI sidecar available here: https://www.arcadeshopper.com/wp/store/#!/Sidecar-SAMS-with-44pin-header-for-TIPI/p/176285041/category=22255086

What about the NanoPEB and CF7 sidecars?

    • NanoPEBs are available periodically on ebay and arcadeshopper.com a limited quantity is produced and sold without any regular schedule.
      CF7+ - 32k, Parallel port and Floppy Emulation

      • Includes 32k ram expansion, floppy disk emulation off a proprietorially formatted CF card and a single DTE 9pin RS232 port. This port is not software compatible with most original serial programs
        • TIMXT
        • TI Web Browser
        • TELCO has been patched
        • MassXfer has been patched
        • TE2 works out of the box
        • Any program that uses DSR access to RS232 should also work as long as it enables the port.
    • CF7’s are also available on Ebay and arcadeshopper.com randomly..
      CF7+ - 32k, Parallel port and Floppy Emulation

      • Includes 32k ram expansion, floppy disk emulation the same as the NanoPEB and a single IBM PC cable compatible Parallel port on a 25 pin connector.
      • The parallel port is not software compatible with programs that do not make DSR calls. Using the PIO device works fine in basic and other utilities that use that DSR.
    • Both the NanoPEB and CF7 file system on the CF card can only be read and written using the software on the author’s site, TIDIR from Fred Kaal or the java application TIImageTool.
    • Both the NanoPEB and CF7 are unable to easily have their 32k disabled to coexist with other cards that provide 32k. So If you wanted to use one in conjunction with say a TIPI card, you’d need a way to plug both into the side port and only have one enabled 32k card.

What is TIPI?

    • TIPI is a inexpensive hard drive replacment for the TI-99/4a and Geneve in GPL/Rompage mode.
    • TIPI stands for TI to Raspberry PI connection. This leverages the cheap storage and internet connectivity of the PI for use on your TI-99/4a computer. In a nutshell, you get an equivalent to a hard disk, floppy drive emulation and internet connection as well as access to peripherals on the PI (such as the mouse, ports etc)
    • The raspberry PI is connected to the TI-99/4a via a sidecar or PEB box TIPI card.
      • The sidecar TIPI card requires the sidecar 32k card with 44pin connector and external power supply to operate.
      • The PEB card plugs directly into the expansion box and requires a 32k memory expansion to load it’s tools/utilities.
      • There is a new combo 32k/tipi sidecar that will also conveniently fits in a speech synth case.
    • For updated/more info see: http://ti994a.cwfk.net/TIPI.html
    • TONS of info here: https://www.arcadeshopper.com/wp/the-ti-raspberry-pi-connection/

How about the Speech Synthesizer

    • Just plug it in to the sideport of your TI-99/4(a) and it is available to any program that supports it.
    • Technical information http://www.unige.ch/medecine/nouspikel/ti99/speech.htm
    • General Information
      • Extended basic will only say the words in the included vocabulary in the Extended basic manual. Make sure you enter them in UPPER CASE ONLY if you use lower case it will say “UH OH” for every letter..
      • Terminal Emulator II will do “text to speech” and say any word spelled in the format documented in the manual.
      • Speech Editor will also do “text to speech” but they are pretty rare!
    • What about the little door on the front?
      • Originally when the synthesizer was designed, it was programmed with about 300 words and phrases (the ones you can get from CALL SAY in Extended BASIC). TI’s intention was to sell add-in modules that went into this compartment that would add additional words to the resident vocabulary. TI then figured out how to do unlimited text to speech through software, added that to Terminal Emulator II, and then there was no need for the add-in modules. So none were ever sold and very few of the speech synthesizers even have the connector inside the door for these to plug into.
    • I hear there are a couple lines that aren’t passed through the speech synth? (these can be jumpered across the board to resolve)
      • 5v on pin 1 (Jedimatt sidecar32 requires this OR an external power supply)
      • Sound through (SID99 requires this to play sound from the PBOX)
    • Can I put the speech synth in the console?
      • If you are handy with a soldering iron: http://www.mainbyte.com/ti99/speech/speech_console.html
    • Can I put the speech synth board in the PEB?

 

What is this Peripheral Expansion Box you speak of?

 

Can I hook up a PC keyboard to my TI?

 

What Joysticks and controllers are available for my TI?

 

Can I hook up a modem to my TI?

    • Yes but to hook up a modem you need a RS232 serial port
      • with a PEB and a RS232 card
      • with a sidecar RS232
      • with a NanoPEB
      • with a UberGROM board with the serial interface)
    • What is the pinout of the TI RS232 serial port?
    • What is the pinout of the NanoPEB?
    • What Terminal Software is there for the TI
      • Terminal Emulator II is a cartridge that will allow you to connect to RS232/1 or 2 at 110 and 300 baud. This software has it’s own “terminal protocol” that allowed for changing character definitions and other cool stuff. Runs on a stock console without memory expansion.
      • FastTerm was a popular terminal program that gave you basic terminal functions and xmodem transfers. 32k and disk system required.
      • Telco is the most full featured terminal program for the TI, it included multiple terminal (including ANSI but no color) and transfer protocols, phone book and auto dialer and many other features. 32k and disk system required
      • Term80 allowed you to have an 80 column terminal on your 99/4a with the stock VDP, hard to read but amazing! 32k and disk system required
      • Mass Transfer was a terminal program that worked well to send multiple files between computers. 32k and disk system required (included in XB27 suite)
      • TIMXT is the latest terminal released allowing for up to 38000 baud full color ANSI terminal on a NanoPEB or TI rs232 card and 80 column text with the F18a VDP. 32k, rom load or disk system and F18a required. http://atariage.com/forums/topic/265573-timxt-terminal-emulator-dev/?do=findComment&comment=3761846

 

Can I hook up a printer to my TI?

    • Sure with the following cards/addons you can hook up a printer.
      • TI RS232 card has two serial ports and one parallel port. You can order a TI parallel cable here: http://www.cabledepot.com/05MCOlderTI.html
      • NanoPEB has a single serial port that is the same as a PC serial port. 9 pin
      • CF7 has a single parallel port that is the same as a PC parallel port 25 pin
      • There was a cartridge based program that included a cartridge based parallel port, these are relatively rare.
    • If you don’t have a printer, you can use the program TI PRINT from Fred Kaal to use your PC’s printer with your TI. You just need a serial port (same as the HDX set up) and this software: www.ti99-geek.nl/Projects/ti99print/ti99print.html

 

Disk drives?

    • TI made a stand alone disk controller and a PEB card that supported up to DS/SD diskettes. There is an 80 track modification available from hummingbird eproms to add 80 track drives to this controller.
    • Corcomp made a PEB disk controller and a sidecar “9900 Micro” that supported up to DS/DD diskettes. http://mainbyte.com/ti99/hardware/9900_micro/9900_micro.html
    • Myarc made a PEB disk controller that supported up to DS/DD diskettes.
    • Myarc also made a HFDC (hard, floppy disk controller) for the PEB that will support up to 80 track DS/DD disks on a 4/a and fully format 1.44mb HD disks on a Geneve (with the appropriate drive).

 

Hard drives?

    • TIPI provides a hierarchical file system (essentially a hard disk as far as the TI is concerned) for more information see the TIPI description above or http://ti994a.cwfk.net/TIPI.html
    • Myarc produced a Winchester Personality Card that allowed you to connect a WDS-100 SASI controller to your TI and then some MFM hard drives to the controller. This supported up to two 20meg drives. There are only three I know of in collectors hands.. Good luck on finding one!
    • Myarc produced a HFDC controller that in addition to disk drives supported up to 2 MFM hard drives as well, I have a 40mb one on my Geneve, not sure the max limit.. (rare)
    • S.N.U.G produced an excellent SCSI controller card that is compatible with the TI and Geneve. These are difficult and expensive to find for sale. http://www.s-n-u-g.de/home/index_e.php
    • WHSCSI card (Western Horizon SCSI card) Handles 7 SCSI drives and with a HP SCSI port splitter box could handle 6 more SCSI drives for a total of 13 SCSI drives (rare)
    • Therry designed a IDE controller for the 99/4a and some have been built as part of a group project among TI enthusiasts. These were recently produced by shift838 but they are sold out, but they are open source you can build your own.

Disk emulators?

 

RAM Disks?

    • Corcomp’s 128k and 512k memory cards are basically only usable as RAMDISK these had no battery backup so power off=blank
    • Myarc’s 128k and 512k memory cards contain a DSR routine for RAMDISK, these had no battery backup etc..
    • Horizion RAMDISK is a dedicated ramdisk of battery-backed memory. It will survive a reboot/power down as long as your batteries are good. Various sizes were released getting bigger as ram prices dropped.

 

 

A web browser? seriously?

Compatible computers?

My TI isn’t working right! help!

    • Keyboard issues
      • The keyboard is connected directly to the TI motherboard with a pin connector. This can become loose/dirty and may need cleaning/reseating. There is no logic within the keyboard is is merely shorting the keyboard lines when you hit the keys. keyboard_schematic.jpg
      • If your cable is damaged there are replacements available at http://www.arcadeshopper.com/under hardware/cables
      • Alpha Lock issue: With the alpha lock key on you are unable to use the up direction with the joysticks. Release alpha lock to play games OR do this fix: http://mainbyte.com/ti99/console/alpha_lock.html
      • What keyboard do I have? There were at least 5 manufacturers of keyboards for the 99/4a. http://mainbyte.com/ti99/keyboard/keyboard.html has good pictures/info/schematic.
      • keyboard_front.jpg
        • Mitsumi: These keyboards do not have any solder points except for the alpha-lock key connection and the ribbon cable.
        • Image result for ti-99 keyboard mitsumi
        • Alps and others: These keyboards have solder points on the back of the PCBoard keyboard_back.jpg
          • these keyboards sometimes have dirt/corrosion in the switches that can be cleaned with contact cleaner or alcohol.
      • Console just BEEPS
        • The start up routine of a 99/4a initializes the sound chip with a tone and then the rom boot routine shuts off the tone.. If it just beeps either there is a bad connection to a peripheral OR a board level issue that is causing the startup routine to “lock”. Check all socketed chips for good connection/corrosion etc and reseat.
      • Scrambled/Garbled screen graphics/text
        • 80% of the time this is VDP ram and it will need to be replaced.
          • Here is a great page on how to determine what RAM chip is bad: http://www.ninerpedia.org/index.php?title=Troubleshooting
            • Don’t use 4116 ram, it costs more than 4164 and uses more power/generates more heat. 4164 will last longer.  See this post for more info https://atariage.com/forums/topic/257923-replacing-4116-ram-with-4164-for-reliability/
            • VDP Ram is soldered into the motherboard and will need to be desoldered and replaced (suggest it is replaced with sockets and new ram inserted into the socket) this ram is TMS4116 static ram. Located in number 6 in this photo: http://mainbyte.com/ti99/hardware/big_mother2.jpg
            • The F18A VGA VDP replacement contains it’s own VDP ram so replacing the TMS9918a VDP in your 4/a with a F18A will also replace bad memory without having to solder..
        • On NTSC/USA machines TMS9918a VDP is the hottest component on the motherboard and this tends to end it’s life prematurely. Daily use consoles tend to have the VDP fry sooner or later. This chip is socketed so it is relatively easy to replace. It is covered with heatsync compound and there is a metal slug that sits on top of it under the RF shield on a original 4/a. On a QI model there is a metal heat-sync clipped to the 9918a.
      • Cartridges don’t work or don’t work reliably.
        • The TI cartridge port is the most used part of a console. It tends to get dirty and gummed up. Info here on cleaning carts and the port: http://mainbyte.com/ti99/minimem/cart_fix.html
        • Replacement cartridge port boards are available on ebay and from vendors.