TI-99/4A FAQ: Memory expansion

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 memory expansion.
        • Extended Basic can use up to 24k of the 32k memory expansion and 8k  is available for loading assembly language programs.
        • Logo can use 32k
        • Multiplan requires 32k memory expansion
        • TI-writer requires 32k memory 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? 

          If you have an expansion box:

          You can insert a 32k ram card into the Peripheral expansion box,  Many were made by TI, Corcomp and others. (see below under PEB cards)

          You can also use a SAMS card in a PEB that provides 32k as well as additional memory addressable by SAMS compatible software.

          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

          TI also produced a 32k sidecar that plugged in the expansion port on the right side of your 99/4a.

          Myarc designed and produced  the MPES/50 sidecar expansion system that included 32k.
          Image result for myarc expansion system

          Boxcar 32k is a sidecar 32k expansion system

          JediMatt42 designed and released a new 32k sidecar in 2018 that has a very small footprint and expansion pins for future add on devices such as TIPI:

          You can buy a Jedimatt42 sidecar 32k here:

          There are a couple of projects to add the 32k expansion memory directly to the console

          Also you get 32k ram expansion with the NanoPEB and CF7 sidecars.

           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.

                • Buy the board here and build your own: https://www.ar
                • Contact Kasrul on atariage to purchase an assembled one.
                • More info/discussion here: http://atariage.com/forums/topic/252171-1-meg-super-ams-discussion-thread/

          Sidecar SAMS – Equivalent to the 1mb SAMS pbox cards now in tiny sidecar format with 44pin header compatible with the TIPI sidecar available here:

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