Enter the TI-GROMmy, a modern replacement board for the system GROMs of a TI-99/4A. It is flash programmable from the 99/4a and can contain multiple grom binaries and plug into your console directly in the grom sockets.

Uses STM32G070KB6 MCU.

• 128K Flash
• 36K SRAM
• 32-pin LQFP

Installation

The grommy2 boards are shipped preprogrammed.

For installation, please refer to the pictures in the presentation.

the process is simple: remove all three system GROM chips, and plug the grommy2 board in their place.

The pictures show installation to the two leftmost GROM sockets. That’s how I have also installed the boards.

However, since the GROM chip sockets share all pins, it is also possible to plug the board into the two rightmost sockets. The only reason why this would make sense is if the contacts are somehow bad on the two leftmost sockets, or they are damaged or something like that.

After installation, and make sure all pins on the bottom side are in the socket and the alignment is good. I always look from the side to make sure that’s the case, see the circled area in the picture below.

Power on the console. It should boot up normally. The red LED will be lit when the grommy2 is active. During normal boot with default console GROM code the LED will be lit almost all the time, since the console is executing GPL code from GROMs almost all the time.

Option switches

If you want to install switches to select options, please refer to the page 4 of the presentation. It shows two signals of interest. All signals mentioned below are available on the side connector of the grommy2, the right angle pin header pictured above.

• PA3 – /BANK1, when brought low, chooses the GROM bank #1 during the boot process. Bringing it low means connecting it to Vss on the same connector. If you want to have a switch for this purpose, connect it between PA3 – /BANK1 and Vss.
• PA2 – /FAILSAFE, when brought low, chooses the failsafe mode during the boot process. Bringing it low means connecting it to Vss on the same connector. If you want to have a switch for this purpose, connect it between PA2 – /FAILSAFE and Vss.
• Vss on the grommy2 side connector is almost the same signal as the console ground, but it is not the exact same signal as the console ground is unfortunately not available in the GROM socket pins. This is why I recommend placing the switches between Vss on the side connector and the /BANK1 and/or /FAILSAFE pins.

Banking hardware selection

Please refer to page 5 of the presentation. This is optional.

Programming the grommy2

Please see https://github.com/Speccery/StrangeCart-Doc/blob/main/grommy2/README.md

For example GPL code, please see https://github.com/Speccery/1bpp2basic/blob/main/config.gpl . This is the source code for the grommy2 configuration utility.

https://forums.atariage.com/applications/core/interface/file/attachment.php?id=1213753&key=08137665eca7c3dbe52007bbb3edb9d6

Adventure cartridge – Scott Adams adventures

https://www.mocagh.org/loadpage.php?getcompany=ai&npp=25&whatsnew=0&start=0&series=TI-99%2F4A+Adventures+Series  has a nice list of the games available for this cartridge. You need a cassette player/cable or disk system to load the games with the adventure module. No other expansion is required it works fine on stock console.

Adventure Games:

• Adventure #0 – Special Sampler (1979) (Adventureland demo)^[4]
• Adventure #1 – Adventureland (1978)
• Adventure #2 – Pirate Adventure (1979)
• Adventure #3 – Secret Mission (1979)
• Adventure #4 – Voodoo Castle (1979)
• Adventure #5 – The Count (1979)
• Adventure #6 – Strange Odyssey (1979)
• Adventure #7 – Mystery Fun House (1979)
• Adventure #8 – Pyramid of Doom (1979)
• Adventure #9 – Ghost Town (1980)
• Adventure #10 – Savage Island (1980)
• Adventure #11 – Savage Island Part Two (1981)^[5]
• Adventure #12 – Golden Voyage (1981)^[6]
• Adventure #13 – Sorcerer of Claymorgue Castle (1984)^[7]
• Adventure #14 – Return to Pirate’s Isle (1984)

Others listed: https://intfiction.org/t/list-of-games-in-scott-adams-ti-99-4a-format/49771

Return to Pirate’s Isle

This game is unique as it was only created for the TI-99/4A (officially adventure #14) and it is the first graphical adventure game published for home computers.

Infocom

Infocom officially released the following games for the TI-99/4A

• Zork I
• Zork II
• Zork III
• Enchanter
• Sorceror
• Deadline
• Witness
• Starcross
• Suspended
• Planetfall
• Hitchiker’s Guide to the Galaxy
• Infidel
• Cutthroats
• Sampler

The TI community has released an updated interpreter that supports all of the original games plus additional

• Ballyhoo
• Suspect
• Leather Goddesses of Phobos*
• Spellbreaker
• Seastalker

A recent infocom compatible release was made that includes a TI-99/4A release

Hybernated – 1 https://atariage.com/forums/topic/321529-for-fans-of-old-infocom-games-something-new/

Abrreviations.
By Dan H. Eicher
<Eicher@Delphi.com>
      
    AVPC - Advanced Video Display Processor, produced by Digit Systems
            (Tom Spilane) - This PBOX card use an 9938. 
    
    c - Small C by Clint Pulley for the 99/4a.
    
    E/A - Editor Assembler.
    
    FDC  - Floppy Disk Controller. 
    
    FWEB - Funnel Web.
                
    GRAMULATOR - Graphics Ram Module produced by Cadd Electronics
                 allows the user to load/modify and run cartridges.
                 Unlike the GramKracker produced by Millers Graphics
                 with modifications, this unit could also run MBX
                 modules.
                      
    GRAM KRACKER - See Gramulator.

    Grand Ram - A ramdisk produced by DataBiotics. Unique in that 
           it both battery backed up like a Horizon Ramdisk and 
           provided print spooler software (like the Myarc 512K)
           card. It also included connectors on board to connect
           to emulate the PBOX bus and cartridge port.
    
    GROM - Graphic ROM  
           Rom Memory developed by TI that automatically increments.
            
    HFDC - Myarc Hard Floppy Disk Controller.
    
    MBP - Eight port analog to digital card with real time clock.
    
    MBX - Milton Bradley Expansion Unit (yes the toy maker) allowed 
          the 99/4a to use voice directed games.
        
    PBOX - Peripheral Expansion Box also known as PEB.

          
    PC99 - A software package for MSDOS PC's (486-50 or faster) that
           emulate a TI99/4A. This is commercial software and well 
           supported. 
           
    PGRAM - Like the GramKracker, but on a PBOX card. 
    
    PIO - Parrallel/Printer Port.
        
    POP-CART - Cartridge produced by OPA that up to 512K of grom
               code and any number of cartridges could be placed.

    SOB - Son Of a Board. This board also plugs into the console,
          in the GROM1 socket. It adds an enhanced menu upon power
          up and fixes some video initialization problems that are
          transparent, unless you are using a 9938 or 9958 video 
          controller chip in your system. 
      
    TIM - TI Image Maker. This is a an 80-column board produced by 
          OPA. It had a Yamaha 9958 chip and came bundled with the
          SOB. It mounts inside the TI console in the TMS9918 socket.

    V9t9 - A software package for MSDOS PC's (386-25 or faster) that
           emulates a TI99/4A. This is freeware (produced by Ed. 
           Swartz) and no support from the author is available,
           but the source code is.
           
    XB  - Extended Basic.

Many Sidecar Expansions were made for the TI-99/4A:

TI Sidecars:

• Speech Synthesizer
  • 
• 32k Memory Expansion
  • 
• SS/SD Disk controller
  • 
  • 
• RS232
  • 
  • 
• PCode
• Video Controller
• Solid State Thermal Printer
  • 

Corcomp Sidecars:

• CC9900 Micro Expansion System
  • The 9900 Micro expansion from Corcomp provided 32k and also an optional board can be installed to provide a DSDD disk controller and RS232/PIO ports
  • 
  • 
  • Power Supply  5 pin DIN
• Corcomp Clock
  • 
• Corcomp 256/512k Ramdisk
  • 

Myarc Sidecars

 

Other Sidecars

• Boxcar Peripherals RS232
  • 
• Axiom ParallAx Printer Interface
  • 
• Triton Turbo XT
  • 
  • 

Homebrew Sidecars

• JediMatt42
  • 32k RAM Sidecar
    • 
    • https://jedimatt42.com/ti32kmem.html
  • TIPI Sidecar (ram card with 44pin required)
    • 
    • https://github.com/jedimatt42/tipi/
• Arcadeshopper
  • SAMS 1mb Sidecar
  • 
• Jgparker
  • 32k/TIPI combo card
    • 
    • fits in original speech synth case (after removing original board) also 3d printed cases are available
    • https://github.com/jgparker/tipi

External Power Supplies:

• TI-99/4A USA: 

Internal Power Supplies:

Power supply from a 99/4 (NOTE: NOT COMPATIBLE WITH 4/A)

Power supply from a 99/4A

Power supply from a 99/4A QI

 

This is the connector on the back of the console that the ac adapter plugs into. Some of these connectors have 4 pins, while others have 3. The newer power supplies (QI) only have 2 pins. They way they were set up you can use any ac adapter with any of the consoles.
	The AC voltages in are: 1. Black 8 volt 2. White 16 volt 3. Red 5 volt 4. No connection

The power supply is a very standard setup, and could be replaced by any standard PC power supply.
	The DC voltages out are: Pin 1 = -5 volt Pin 2 = +12 volt Pin 3 = GND Pin 4 = +5 volt.

No AC Voltage? check the fuse!

TI was required by the UL to add a fuse to the external power supply. Their solution? add a pigtail to the power cord with the fuse in a little plastic box.

These fuses tend to blow after so many years of use, so the fuse needs to be replaced or just remove the pigtail if you are using a power strip with built in circuit breaker making the fuse unnecessary.  You will find it’s just stuck on the old plug with some adhesive and it should come apart with some effort.

Fuse type:  4/10A 250V 

 

Schematic for power supply (not QI)

Here is an interesting project replacing the console power supplies with a new board: