Cyclone Analogic Bass Bot Bedienungsanleitung PDF herunterladen (Seite 3)

Determining whether a machine has Option A, B or C

If you have a machine without its original documentation, you can determine which memory backup option

it uses by reading the section above 0 - What this manual does not apply to, and if it is a machine which has

one of these options, looking for the VRAM wire which is pictured next to the positive end of the battery

compartment, in the section below: Testing the VRAM voltage.

If the machine lacks this wire, its memory backup arrangement is Option A. If there is such a wire, then the

arrangement is either Option B or C. A machine which we shipped with Option B may have since had a

lithium coin-cell added, which means it is now Option C. Alternatively, an Option C machine may have had

its coin-cell removed, or this coin-cell may have insufficient charge to power the memory, in which case it is

effectively has Option B. To distinguish between Option B and C, remove the back of the machine as noted

in the section below Testing the voltage of the 2032 coin-cell battery to see if there is such a battery, and to

measure its voltage if there is one.

Machines modified during and after February 2005, starting with serial number 289, generally have Option

B if they were for an overseas customer and Option C if they were for an Australian customer. However,

machines which were modified earlier than this may have been returned here for further work, and we may

have changed them from Option A to Option B or C then.

2 - The TB-303's original Memory Backup System

The TB-303 Bassline contains a 42 pin single-chip microcontroller, which is generally referred to as the

"CPU" (Central Processing Unit). This single chip device contains a 4 bit CPU, input-output sections, a

limited amount of read-write memory (Random Access Memory = RAM), and a permanently programmed

Read Only Memory (ROM). The ROM section of the chip is manufactured with a pattern of ones and zeroes

which form the computer program which causes this chip to perform its sequencer functions.

The microcontroller chip connects to three battery backed up low-power static RAM chips, each of which

has 1024 locations of 4 data bits. These chips total 1.5k bytes of memory, and are used to store the patterns,

pre-scale values, pattern lengths and the track data. Low power static RAM chips retain their data as long as

power is applied to them, since each memory cell is a simple flip-flop of six transistors. A flip-flop can be

set into either the flipped state (low on the left, on high the right) or the flopped state (high on the left and

low on the right) and will remain in this state as long as power is applied. That state can be read, or later

changed. (Dynamic RAM chips, as used for the main memory in PCs, are cheaper per bit, but require

constant external refresh drive activity to retain their data, which is stored in capacitors.)

The six transistor memory cells used in the TB-303's original memory chips cause these chips to consume a

very small current indeed when they are not being read or written to. This is the backup current. The total

current drawn by all three chips is typically less than 1/100th of a microamp - less than 1/100,000,000 amp.

With the 32 Bank Memory System, which some Devil Fishes have, we replace these chips with three larger

ones, which also use these six transistor cells. With these three larger chips, the backup current is typically

0.02 microamps at cool room temperature, such as 18°C, rising to something like 0.5 microamps at 50°C.

Both the old and new chips normally operate from 5 volts, and will retain their data as long as their supply

voltage is above about 2.5 volts.

In a standard TB-303, the VRAM supply voltage for the memory chips is supplied via two pathways, both

involving a silicon diode (a one-way valve for electrons). In practice, one or the other pathway will be

active, since the pathway with the highest supply voltage will raise VRAM to that voltage minus the 0.5 to

0.6 volt drop of the diode:

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Cyclone Analogic Bass Bot Bedienungsanleitung Seite 3