TMS6100

Key takeaways

TMS6100 belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect TMS6100 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of TMS6100 from memory before moving on to harder problems.

Reference excerpt

The Texas Instruments TMS6100 Voice Synthesis Memory (VSM) is a 1 or 4-bit serial mask factory-programmed read-only memory IC. It is a companion chip to the TMS5100, CD2802, TMS5110, (rarely) TMS5200, and (rarely) TMS5220 speech synthesizer ICs, and was mask-programmed with LPC data required for a specific product. It holds 128 KiB (16 KiB) of data, and is mask-programmed with a start address for said data on a 16 KiB boundary. It is also mask-programmable whether the /CE line needs to be high or low to activate, and also what the two (or four) 'internal' CE bits need to be set to activate, effectively making the total addressable area 18 bits. Finally, it is mask-programmable whether the bits are read out 1-bit serially or 4 at a time.

TMS6125 The TMS6125 is a smaller, 32 Kib (4 KiB) version of effectively the same chip, with some minor changes to the 'address load' command format to reflect its smaller size. Texas Instruments calls both of these serial roms (TMS6100 and TMS6125) "VSM"s (Voice Synthesis Memory) on their datasheets and literature. Both VSMs use 'local addressing', meaning the chip keeps track of its own address pointer once loaded. Hence every bit in the chip can be sequentially read out, even though internally the chip stores data in 8-bit bytes. (For the following section, CE stands for "Chip Enable" and is used as a way to enable one specific VSM.)

Commands The VSM has supports 4 basic commands, based on two input pins called 'M0' and 'M1':

no operation/idle: this command tells the chip to 'do nothing' or 'continue doing what was being done before'. load address: this command parallel-loads 4 bits from the data bus. to fully load an address, this command must be executed 5 times in sequence, for a load of a 20 bit block (LSB-first 14 bit address, 4 CE bits, and two unused bits, effectively 18 address bits) into the internal address pointer. On the TMS6125 the command must be executed 4 times instead, and only a 16 bit block is loaded (12 address bits, two unused bits, and two CE bits). read bit: this reads a single bit at the loaded address, and advances the 3 bit 'bit pointer' to point to the next bit within the address; if the bit pointer overflows, the address pointer is incremented. If the address pointed to on a specific chip is outside of the mask-programmed range of said VSM, the VSM will leave the data bus 'open' in a high impedance state, so another chip wired in parallel (which has the address within its mask-programmed range) can supply the data instead. A rarely used mask option made the read bit command read 4 bits at once; this was used on a few non-speech products, and could not be used with the TI-manufactured LPC speech ICs. read and branch: this reads 16 bits of data from the current address(and bit?) pointed to, and loads the value read into the address pointer, leaving the high bits of the address pointer alone. (This was intended for making VSMs with multiple languages available, where the initial load addresses could remain static, so for example they would not require changes to code in a microcontroller, and only the values pointed to in the VSM needed changing. In practice it doesn't seem to have ever been used, as it doesn't work when more than one VSM chip shares a bus, which is what was done in most cases.)

Part Numbering When used on Texas Instruments' Consumer Division products, the VSMs are always marked CDxxxxx where xxxxx is a 4 or 5 digit mask rom ID code, typically 23xx or 62xxx. The chips are SOMETIMES (typically after 1981) also marked TMC0350, as this seems to be the 'internal use class' of the chip. The very first VSMs (used in the Speak and Spell, 1978 version) were marked TMC0351 and TMC0352 and did not have a CD number. These two SEEM to have been 'grandfathered in' as CD2300 and CD2301, as all later VSMs start at CD2302 (used in the 'Vowel Power' Speak and Spell expansion cartridge). It should also be noted that CD22xx, CD25xx and CD28xx numbers are used for chips that are NOT VSMs. When used on Texas Instruments' non-consumer division products (such as generic voice chips for other computers/measurement devices which were still TI-branded) the chips are labeled VMxxxxx. When used on 3rd party products, the chips are marked CMxxxxx instead. The numbering scheme for the xxxxx part seems to be common between both CDxxxxx and CMxxxxx chips (but NOT VMxxxxx chips), so no chip of either series will have a common xxxxx number.

References

Worked examples

Example 1 — a first encounter with TMS6100

Start with the simplest possible case. Write down what TMS6100 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to TMS6100 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about TMS6100 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of TMS6100

In research: TMS6100 appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses TMS6100 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: TMS6100 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Integrated circuits, Sound chips, Speech synthesis, so understanding it makes those chapters shorter.
In everyday life: Look for TMS6100 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study TMS6100 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what TMS6100 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain TMS6100 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is TMS6100 in simple terms?

The Texas Instruments TMS6100 Voice Synthesis Memory (VSM) is a 1 or 4-bit serial mask factory-programmed read-only memory IC. It is a companion chip to the TMS5100, CD2802, TMS5110, (rarely) TMS5200, and (rarely) TMS5220 speech synthesizer ICs, and was mask-programmed with LPC data required for a…

Why does TMS6100 matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study TMS6100?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on TMS6100.