DRAM that was accessible only indirectly through the video display controller, which crippled the performance of the TI-99/4. TI developed the TM990 series of computer modules, including CPU, memory, I/O, which when plugged into a card frame could form a 16-bit minicomputer. These were typically used for process control. A microprocessor trainer was released in the form of the TM990/189. TMS9900 Family Product Development The second generation of the TMS9900 family of microprocessors was the TMS9995 which provided "functional performance at speeds 3 times faster than any previous 9900 family processor", largely due to the inclusion of instruction prefetch technology. In the home computer arena, the TMS9995 only found use in the Tomy Tutor, an esoteric TI99-4/A upgrade called the Geneve 9640, and a project printed in Electronics Today: the Powertran Cortex. It was planned to be used in the TI-99/2 & TI-99/8 computer systems, but neither advanced past the prototype stage. TI later developed the more powerful TMS99000 family of microprocessors, which was used as the CPU in the 990/10A minicomputer as a cost reduction. Unfortunately, by the time the 990/10A made it to market, the end of the minicomputer era was already in sight. The TMS99000 family includes two microprocessors, the TMS99105A and the TMS99110A, which are identical except for the contents of on-chip macrostore ROM memory (macrostore memory contains added functions or instructions through emulation routines written in standard machine code). The on-chip ROM Macrostore in the TMS99110A microprocessor contains floating point instructions which are available as part of the machine language instruction set, while the baseline TMS99105A does not. Both chips can implement Macrostore instructions in an external ROM. A third member of the TMS99000 family, the TMS99120, was announced but may never have been commercially produced. The on-chip ROM Macrostore in the TMS99120 was to contain run-time support routines for the PASCAL high-level language. The instruction set for the TMS99000 family extends the 9900 instruction set while keeping compatibility. The additional instructions includes those for signed multiply and divide (first appearing in the TMS9995), long-word shift, add, and subtract; load status register, load workspace pointer, stack operations, multiprocessor support, bit manipulation. Members of the family can access 256KB of memory through code/data segmentation, and may use the TIM99610 memory mapper to address up to 16MiB. The architecture contains many other advances over the TMS9900 and TMS9995. Variants Notes References External links TMS9900 manuals and references