GROM (computer module)

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A GROM or Graphics Read Only Memory ( English read-only memory , ROM ) is a read-only memory with an internal addressing continuously by, after a single Adressetzen, d. H. data can be read out without new addressing. This organization means that a large amount of data can be accessed via just a single port.

Structure and operation

Internally, the block consists of an address counter and a read-only memory. The read-only memory is read out via an 8-bit data bus. The address counter is incremented after each read access. The address of the address pointer can be read or written as two 8-bit values ​​via the same data bus. The function is controlled via the inputs M0 / M1. The TMS 6100 also has a jump mode that allows the next two words (16 bits) to be loaded as a new address.

Manufacturing

Texas Instruments was the only notable manufacturer of GROM devices. Only mask-programmed modules were produced for general sale .

variants

  • TMC 0340 8 bit GROM with 6 KiB and 14 bit address pointer
  • TMC 0350 (also TMS 6100) Voice Synthesis Memory (VMS) - 128 KiBit serial ROM organized as 16 KiB. Especially for the speech synthesizer (TMC0270 / 5100 ff).
  • TMC 0355 (also TMS 6125) 32 KiBit serial ROM, organized as 4 KiB. Especially for the speech synthesizer (TMC0270 ff and TMS 5220 ff).
  • Pin-compatible replacement circuits with RAM for development purposes were available from third-party manufacturers for the TMC 0340.

Labelling

Since the modules were always manufactured on behalf of the customer, there is often not the type, but only a content identifier according to the customer order on the housings

  • CDxxxx - for building blocks in TI consumer products (home computers, Speak & Spell etc.)
  • VMxxxx - for blocks in other TI products (measuring devices)
  • CMxxxx - for modules for external (non-TI) customers.

TMC-0340 products have numbers in the 21xx range, whereas TMC-0350 modules are marked with 23xx, 26xx, 35xx or 62xx. If modules with the same content were delivered to both internal and external customers, the same number (with a different prefix) was printed.

use

The Texas Instruments TI-99 / 4A home computer contained three components for functions used only for system start-up, math functions and the BASIC. Various modules for the TI 99/4 also contained GROM components. Practically all applications of the TI speech synthesizer chips (e.g. Speak & Spell , Furby ) use a TMC 0350.

Individual evidence

  1. ↑ TMS 5220 Voice Synthesis Processor Data Manual.Retrieved August 17, 2014.
  2. ↑ a b Texas Instruments Speech - Integrated Circuits. Retrieved August 17, 2014.
  3. ↑ Inside a Speak & Spell.Retrieved August 17, 2014.